diff --git a/core/fdrm/fx_crypt.h b/core/fdrm/fx_crypt.h
index f199bc1..aa0729a 100644
--- a/core/fdrm/fx_crypt.h
+++ b/core/fdrm/fx_crypt.h
@@ -9,7 +9,7 @@
 
 #include <stdint.h>
 
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 struct CRYPT_rc4_context {
   static constexpr int32_t kPermutationLength = 256;
diff --git a/core/fpdfapi/edit/cpdf_pagecontentgenerator.cpp b/core/fpdfapi/edit/cpdf_pagecontentgenerator.cpp
index aa16328..20b9111 100644
--- a/core/fpdfapi/edit/cpdf_pagecontentgenerator.cpp
+++ b/core/fpdfapi/edit/cpdf_pagecontentgenerator.cpp
@@ -39,9 +39,9 @@
 #include "core/fpdfapi/parser/fpdf_parser_decode.h"
 #include "core/fpdfapi/parser/fpdf_parser_utility.h"
 #include "core/fpdfapi/parser/object_tree_traversal_util.h"
+#include "core/fxcrt/span.h"
 #include "third_party/base/check.h"
 #include "third_party/base/containers/contains.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/notreached.h"
 #include "third_party/base/numerics/safe_conversions.h"
 
diff --git a/core/fpdfapi/font/cfx_cttgsubtable.h b/core/fpdfapi/font/cfx_cttgsubtable.h
index 30bc353..927f3a9 100644
--- a/core/fpdfapi/font/cfx_cttgsubtable.h
+++ b/core/fpdfapi/font/cfx_cttgsubtable.h
@@ -14,8 +14,8 @@
 #include <vector>
 
 #include "core/fxcrt/data_vector.h"
+#include "core/fxcrt/span.h"
 #include "third_party/abseil-cpp/absl/types/variant.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_CTTGSUBTable {
  public:
diff --git a/core/fpdfapi/font/cpdf_cid2unicodemap.h b/core/fpdfapi/font/cpdf_cid2unicodemap.h
index 6bc5c12..9b06c09 100644
--- a/core/fpdfapi/font/cpdf_cid2unicodemap.h
+++ b/core/fpdfapi/font/cpdf_cid2unicodemap.h
@@ -8,7 +8,7 @@
 #define CORE_FPDFAPI_FONT_CPDF_CID2UNICODEMAP_H_
 
 #include "core/fpdfapi/font/cpdf_cidfont.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CPDF_CID2UnicodeMap {
  public:
diff --git a/core/fpdfapi/font/cpdf_cidfont.cpp b/core/fpdfapi/font/cpdf_cidfont.cpp
index 709517a..c6a71bb 100644
--- a/core/fpdfapi/font/cpdf_cidfont.cpp
+++ b/core/fpdfapi/font/cpdf_cidfont.cpp
@@ -28,11 +28,11 @@
 #include "core/fxcrt/fx_memory.h"
 #include "core/fxcrt/fx_safe_types.h"
 #include "core/fxcrt/fx_unicode.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/stl_util.h"
 #include "core/fxge/fx_font.h"
 #include "third_party/base/check.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 
 namespace {
 
diff --git a/core/fpdfapi/font/cpdf_cmap.h b/core/fpdfapi/font/cpdf_cmap.h
index 0eb033b..443af2f 100644
--- a/core/fpdfapi/font/cpdf_cmap.h
+++ b/core/fpdfapi/font/cpdf_cmap.h
@@ -14,8 +14,8 @@
 #include "core/fpdfapi/font/cpdf_cidfont.h"
 #include "core/fxcrt/fixed_size_data_vector.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
-#include "third_party/base/containers/span.h"
 
 namespace fxcmap {
 struct CMap;
diff --git a/core/fpdfapi/font/cpdf_fontencoding.h b/core/fpdfapi/font/cpdf_fontencoding.h
index cab4b3f..519cd7e 100644
--- a/core/fpdfapi/font/cpdf_fontencoding.h
+++ b/core/fpdfapi/font/cpdf_fontencoding.h
@@ -9,10 +9,10 @@
 
 #include "core/fxcrt/bytestring.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/string_pool_template.h"
 #include "core/fxcrt/weak_ptr.h"
 #include "core/fxge/fx_fontencoding.h"
-#include "third_party/base/containers/span.h"
 
 enum class FontEncoding {
   kBuiltin = 0,
diff --git a/core/fpdfapi/font/cpdf_fontglobals.h b/core/fpdfapi/font/cpdf_fontglobals.h
index f5148a0..e04471e 100644
--- a/core/fpdfapi/font/cpdf_fontglobals.h
+++ b/core/fpdfapi/font/cpdf_fontglobals.h
@@ -15,8 +15,8 @@
 #include "core/fpdfapi/cmaps/fpdf_cmaps.h"
 #include "core/fpdfapi/font/cpdf_cidfont.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/cfx_fontmapper.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_StockFontArray;
 class CPDF_Font;
diff --git a/core/fpdfapi/font/cpdf_tounicodemap_unittest.cpp b/core/fpdfapi/font/cpdf_tounicodemap_unittest.cpp
index a9441ce..fdc35f1 100644
--- a/core/fpdfapi/font/cpdf_tounicodemap_unittest.cpp
+++ b/core/fpdfapi/font/cpdf_tounicodemap_unittest.cpp
@@ -6,9 +6,9 @@
 
 #include "core/fpdfapi/parser/cpdf_stream.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
-#include "third_party/base/containers/span.h"
 
 TEST(cpdf_tounicodemap, StringToCode) {
   EXPECT_THAT(CPDF_ToUnicodeMap::StringToCode("<0001>"), testing::Optional(1u));
diff --git a/core/fpdfapi/font/cpdf_type3char.h b/core/fpdfapi/font/cpdf_type3char.h
index 555873c..1056d9f 100644
--- a/core/fpdfapi/font/cpdf_type3char.h
+++ b/core/fpdfapi/font/cpdf_type3char.h
@@ -14,7 +14,7 @@
 #include "core/fpdfapi/font/cpdf_font.h"
 #include "core/fxcrt/fx_coordinates.h"
 #include "core/fxcrt/retain_ptr.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CFX_DIBitmap;
 
diff --git a/core/fpdfapi/page/cpdf_color.h b/core/fpdfapi/page/cpdf_color.h
index a2ba7cb..3bb358a 100644
--- a/core/fpdfapi/page/cpdf_color.h
+++ b/core/fpdfapi/page/cpdf_color.h
@@ -13,7 +13,7 @@
 #include <vector>
 
 #include "core/fxcrt/retain_ptr.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CPDF_ColorSpace;
 class CPDF_Pattern;
diff --git a/core/fpdfapi/page/cpdf_colorspace.h b/core/fpdfapi/page/cpdf_colorspace.h
index 36b356d..cd73fef 100644
--- a/core/fpdfapi/page/cpdf_colorspace.h
+++ b/core/fpdfapi/page/cpdf_colorspace.h
@@ -21,8 +21,8 @@
 #include "core/fxcrt/bytestring.h"
 #include "core/fxcrt/observed_ptr.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
-#include "third_party/base/containers/span.h"
 
 class CPDF_Document;
 class CPDF_IndexedCS;
diff --git a/core/fpdfapi/page/cpdf_colorstate.h b/core/fpdfapi/page/cpdf_colorstate.h
index 6ddae8a..28d5734 100644
--- a/core/fpdfapi/page/cpdf_colorstate.h
+++ b/core/fpdfapi/page/cpdf_colorstate.h
@@ -12,8 +12,8 @@
 #include "core/fpdfapi/page/cpdf_color.h"
 #include "core/fxcrt/retain_ptr.h"
 #include "core/fxcrt/shared_copy_on_write.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/dib/fx_dib.h"
-#include "third_party/base/containers/span.h"
 
 class CPDF_ColorSpace;
 class CPDF_Pattern;
diff --git a/core/fpdfapi/page/cpdf_dib.h b/core/fpdfapi/page/cpdf_dib.h
index 1ef656a..80610d0 100644
--- a/core/fpdfapi/page/cpdf_dib.h
+++ b/core/fpdfapi/page/cpdf_dib.h
@@ -15,9 +15,9 @@
 #include "core/fpdfapi/page/cpdf_colorspace.h"
 #include "core/fxcrt/data_vector.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "core/fxge/dib/cfx_dibbase.h"
-#include "third_party/base/containers/span.h"
 
 class CPDF_Dictionary;
 class CPDF_Document;
diff --git a/core/fpdfapi/page/cpdf_expintfunc.h b/core/fpdfapi/page/cpdf_expintfunc.h
index 1c501d8..0bda6ae 100644
--- a/core/fpdfapi/page/cpdf_expintfunc.h
+++ b/core/fpdfapi/page/cpdf_expintfunc.h
@@ -11,7 +11,7 @@
 #include "core/fxcrt/data_vector.h"
 
 #if defined(PDF_USE_SKIA)
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 #endif
 
 class CPDF_ExpIntFunc final : public CPDF_Function {
diff --git a/core/fpdfapi/page/cpdf_function.h b/core/fpdfapi/page/cpdf_function.h
index 0aee6bd..e7fda22 100644
--- a/core/fpdfapi/page/cpdf_function.h
+++ b/core/fpdfapi/page/cpdf_function.h
@@ -13,7 +13,7 @@
 #include <vector>
 
 #include "core/fxcrt/retain_ptr.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CPDF_ExpIntFunc;
 class CPDF_Object;
diff --git a/core/fpdfapi/page/cpdf_generalstate.h b/core/fpdfapi/page/cpdf_generalstate.h
index a04a0af..667a8e7 100644
--- a/core/fpdfapi/page/cpdf_generalstate.h
+++ b/core/fpdfapi/page/cpdf_generalstate.h
@@ -14,8 +14,8 @@
 #include "core/fxcrt/fx_coordinates.h"
 #include "core/fxcrt/retain_ptr.h"
 #include "core/fxcrt/shared_copy_on_write.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/dib/fx_dib.h"
-#include "third_party/base/containers/span.h"
 
 class CPDF_Dictionary;
 class CPDF_Object;
diff --git a/core/fpdfapi/page/cpdf_iccprofile.h b/core/fpdfapi/page/cpdf_iccprofile.h
index c49e0e2..407f578 100644
--- a/core/fpdfapi/page/cpdf_iccprofile.h
+++ b/core/fpdfapi/page/cpdf_iccprofile.h
@@ -13,7 +13,7 @@
 
 #include "core/fxcrt/observed_ptr.h"
 #include "core/fxcrt/retain_ptr.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CPDF_Stream;
 
diff --git a/core/fpdfapi/page/cpdf_image.h b/core/fpdfapi/page/cpdf_image.h
index 35357fc..dfd9791 100644
--- a/core/fpdfapi/page/cpdf_image.h
+++ b/core/fpdfapi/page/cpdf_image.h
@@ -11,8 +11,8 @@
 
 #include "core/fpdfapi/page/cpdf_colorspace.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_DIBBase;
 class CFX_DIBitmap;
diff --git a/core/fpdfapi/page/cpdf_indexedcs.cpp b/core/fpdfapi/page/cpdf_indexedcs.cpp
index e35352b..8b59b50 100644
--- a/core/fpdfapi/page/cpdf_indexedcs.cpp
+++ b/core/fpdfapi/page/cpdf_indexedcs.cpp
@@ -19,8 +19,8 @@
 #include "core/fxcrt/fx_2d_size.h"
 #include "core/fxcrt/fx_safe_types.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 
 CPDF_IndexedCS::CPDF_IndexedCS() : CPDF_BasedCS(Family::kIndexed) {}
 
diff --git a/core/fpdfapi/page/cpdf_meshstream.cpp b/core/fpdfapi/page/cpdf_meshstream.cpp
index 13fa8fc..aa3f174 100644
--- a/core/fpdfapi/page/cpdf_meshstream.cpp
+++ b/core/fpdfapi/page/cpdf_meshstream.cpp
@@ -15,8 +15,8 @@
 #include "core/fpdfapi/parser/cpdf_stream.h"
 #include "core/fpdfapi/parser/cpdf_stream_acc.h"
 #include "core/fxcrt/cfx_bitstream.h"
+#include "core/fxcrt/span.h"
 #include "third_party/base/check.h"
-#include "third_party/base/containers/span.h"
 
 namespace {
 
diff --git a/core/fpdfapi/page/cpdf_pageobject.h b/core/fpdfapi/page/cpdf_pageobject.h
index 29ffd2e..95048db 100644
--- a/core/fpdfapi/page/cpdf_pageobject.h
+++ b/core/fpdfapi/page/cpdf_pageobject.h
@@ -13,7 +13,7 @@
 #include "core/fpdfapi/page/cpdf_graphicstates.h"
 #include "core/fxcrt/bytestring.h"
 #include "core/fxcrt/fx_coordinates.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CPDF_FormObject;
 class CPDF_ImageObject;
diff --git a/core/fpdfapi/page/cpdf_psengine.h b/core/fpdfapi/page/cpdf_psengine.h
index 0b82bc0..d93f516 100644
--- a/core/fpdfapi/page/cpdf_psengine.h
+++ b/core/fpdfapi/page/cpdf_psengine.h
@@ -14,7 +14,7 @@
 #include <vector>
 
 #include "core/fxcrt/bytestring.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CPDF_PSEngine;
 class CPDF_PSProc;
diff --git a/core/fpdfapi/page/cpdf_streamcontentparser.cpp b/core/fpdfapi/page/cpdf_streamcontentparser.cpp
index 51553c0..ef93e69 100644
--- a/core/fpdfapi/page/cpdf_streamcontentparser.cpp
+++ b/core/fpdfapi/page/cpdf_streamcontentparser.cpp
@@ -39,12 +39,12 @@
 #include "core/fxcrt/bytestring.h"
 #include "core/fxcrt/fx_safe_types.h"
 #include "core/fxcrt/scoped_set_insertion.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/stl_util.h"
 #include "core/fxge/cfx_graphstate.h"
 #include "core/fxge/cfx_graphstatedata.h"
 #include "third_party/base/check.h"
 #include "third_party/base/containers/contains.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/notreached.h"
 
 namespace {
diff --git a/core/fpdfapi/page/cpdf_streamcontentparser.h b/core/fpdfapi/page/cpdf_streamcontentparser.h
index 28ede19..1aa4e24 100644
--- a/core/fpdfapi/page/cpdf_streamcontentparser.h
+++ b/core/fpdfapi/page/cpdf_streamcontentparser.h
@@ -17,10 +17,10 @@
 #include "core/fxcrt/fx_coordinates.h"
 #include "core/fxcrt/fx_number.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "core/fxge/cfx_fillrenderoptions.h"
 #include "core/fxge/cfx_path.h"
-#include "third_party/base/containers/span.h"
 
 class CPDF_AllStates;
 class CPDF_ColorSpace;
diff --git a/core/fpdfapi/page/cpdf_streamparser.h b/core/fpdfapi/page/cpdf_streamparser.h
index ecefa02..7997494 100644
--- a/core/fpdfapi/page/cpdf_streamparser.h
+++ b/core/fpdfapi/page/cpdf_streamparser.h
@@ -8,9 +8,9 @@
 #define CORE_FPDFAPI_PAGE_CPDF_STREAMPARSER_H_
 
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/string_pool_template.h"
 #include "core/fxcrt/weak_ptr.h"
-#include "third_party/base/containers/span.h"
 
 class CPDF_Dictionary;
 class CPDF_Document;
diff --git a/core/fpdfapi/page/cpdf_textobject.cpp b/core/fpdfapi/page/cpdf_textobject.cpp
index c2265f6..93d26c5 100644
--- a/core/fpdfapi/page/cpdf_textobject.cpp
+++ b/core/fpdfapi/page/cpdf_textobject.cpp
@@ -11,8 +11,8 @@
 #include "core/fpdfapi/font/cpdf_cidfont.h"
 #include "core/fpdfapi/font/cpdf_font.h"
 #include "core/fxcrt/fx_coordinates.h"
+#include "core/fxcrt/span.h"
 #include "third_party/base/check.h"
-#include "third_party/base/containers/span.h"
 
 #define ISLATINWORD(u) (u != 0x20 && u <= 0x28FF)
 
diff --git a/core/fpdfapi/page/cpdf_textstate.h b/core/fpdfapi/page/cpdf_textstate.h
index e6983cc..31eb59e 100644
--- a/core/fpdfapi/page/cpdf_textstate.h
+++ b/core/fpdfapi/page/cpdf_textstate.h
@@ -9,8 +9,8 @@
 
 #include "core/fxcrt/retain_ptr.h"
 #include "core/fxcrt/shared_copy_on_write.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
-#include "third_party/base/containers/span.h"
 
 class CPDF_Document;
 class CPDF_Font;
diff --git a/core/fpdfapi/page/cpdf_transferfunc.h b/core/fpdfapi/page/cpdf_transferfunc.h
index 9ac22f3..bb20dd4 100644
--- a/core/fpdfapi/page/cpdf_transferfunc.h
+++ b/core/fpdfapi/page/cpdf_transferfunc.h
@@ -12,8 +12,8 @@
 #include "core/fxcrt/fixed_size_data_vector.h"
 #include "core/fxcrt/observed_ptr.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/dib/fx_dib.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_DIBBase;
 
diff --git a/core/fpdfapi/page/cpdf_transferfuncdib.h b/core/fpdfapi/page/cpdf_transferfuncdib.h
index 8173109..95ac7dc 100644
--- a/core/fpdfapi/page/cpdf_transferfuncdib.h
+++ b/core/fpdfapi/page/cpdf_transferfuncdib.h
@@ -11,8 +11,8 @@
 
 #include "core/fxcrt/data_vector.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/dib/cfx_dibbase.h"
-#include "third_party/base/containers/span.h"
 
 class CPDF_TransferFunc;
 
diff --git a/core/fpdfapi/parser/cfdf_document.cpp b/core/fpdfapi/parser/cfdf_document.cpp
index ea34fbe..80d2698 100644
--- a/core/fpdfapi/parser/cfdf_document.cpp
+++ b/core/fpdfapi/parser/cfdf_document.cpp
@@ -15,7 +15,7 @@
 #include "core/fpdfapi/parser/fpdf_parser_utility.h"
 #include "core/fxcrt/cfx_read_only_span_stream.h"
 #include "core/fxcrt/fx_string_wrappers.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 CFDF_Document::CFDF_Document() = default;
 
diff --git a/core/fpdfapi/parser/cfdf_document.h b/core/fpdfapi/parser/cfdf_document.h
index f327ab5..3dafa45 100644
--- a/core/fpdfapi/parser/cfdf_document.h
+++ b/core/fpdfapi/parser/cfdf_document.h
@@ -11,7 +11,7 @@
 
 #include "core/fpdfapi/parser/cpdf_indirect_object_holder.h"
 #include "core/fxcrt/retain_ptr.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CPDF_Dictionary;
 class IFX_SeekableReadStream;
diff --git a/core/fpdfapi/parser/cpdf_crypto_handler.h b/core/fpdfapi/parser/cpdf_crypto_handler.h
index ba934cc..c857511 100644
--- a/core/fpdfapi/parser/cpdf_crypto_handler.h
+++ b/core/fpdfapi/parser/cpdf_crypto_handler.h
@@ -17,7 +17,7 @@
 #include "core/fxcrt/bytestring.h"
 #include "core/fxcrt/fx_memory_wrappers.h"
 #include "core/fxcrt/retain_ptr.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CPDF_Dictionary;
 class CPDF_Object;
diff --git a/core/fpdfapi/parser/cpdf_document.cpp b/core/fpdfapi/parser/cpdf_document.cpp
index 373b8bd..f07a4d9 100644
--- a/core/fpdfapi/parser/cpdf_document.cpp
+++ b/core/fpdfapi/parser/cpdf_document.cpp
@@ -25,11 +25,11 @@
 #include "core/fxcodec/jbig2/JBig2_DocumentContext.h"
 #include "core/fxcrt/fx_codepage.h"
 #include "core/fxcrt/scoped_set_insertion.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/stl_util.h"
 #include "third_party/base/check.h"
 #include "third_party/base/check_op.h"
 #include "third_party/base/containers/contains.h"
-#include "third_party/base/containers/span.h"
 
 namespace {
 
diff --git a/core/fpdfapi/parser/cpdf_document.h b/core/fpdfapi/parser/cpdf_document.h
index 4f95917..4e00e51 100644
--- a/core/fpdfapi/parser/cpdf_document.h
+++ b/core/fpdfapi/parser/cpdf_document.h
@@ -17,8 +17,8 @@
 #include "core/fxcrt/fx_memory.h"
 #include "core/fxcrt/observed_ptr.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
-#include "third_party/base/containers/span.h"
 
 class CPDF_ReadValidator;
 class CPDF_StreamAcc;
diff --git a/core/fpdfapi/parser/cpdf_encryptor.h b/core/fpdfapi/parser/cpdf_encryptor.h
index d0aabcc..8f37ef8 100644
--- a/core/fpdfapi/parser/cpdf_encryptor.h
+++ b/core/fpdfapi/parser/cpdf_encryptor.h
@@ -10,8 +10,8 @@
 #include <stdint.h>
 
 #include "core/fxcrt/data_vector.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
-#include "third_party/base/containers/span.h"
 
 class CPDF_CryptoHandler;
 
diff --git a/core/fpdfapi/parser/cpdf_flateencoder.h b/core/fpdfapi/parser/cpdf_flateencoder.h
index a9b37f7..0a871d5 100644
--- a/core/fpdfapi/parser/cpdf_flateencoder.h
+++ b/core/fpdfapi/parser/cpdf_flateencoder.h
@@ -11,8 +11,8 @@
 
 #include "core/fxcrt/data_vector.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "third_party/abseil-cpp/absl/types/variant.h"
-#include "third_party/base/containers/span.h"
 
 class CPDF_Dictionary;
 class CPDF_Encryptor;
diff --git a/core/fpdfapi/parser/cpdf_hint_tables.cpp b/core/fpdfapi/parser/cpdf_hint_tables.cpp
index 2e854f8..027b7e2 100644
--- a/core/fpdfapi/parser/cpdf_hint_tables.cpp
+++ b/core/fpdfapi/parser/cpdf_hint_tables.cpp
@@ -20,8 +20,8 @@
 #include "core/fpdfapi/parser/cpdf_syntax_parser.h"
 #include "core/fxcrt/cfx_bitstream.h"
 #include "core/fxcrt/fx_safe_types.h"
+#include "core/fxcrt/span.h"
 #include "third_party/base/check.h"
-#include "third_party/base/containers/span.h"
 
 namespace {
 
diff --git a/core/fpdfapi/parser/cpdf_parser.cpp b/core/fpdfapi/parser/cpdf_parser.cpp
index c5a9f98..0834400 100644
--- a/core/fpdfapi/parser/cpdf_parser.cpp
+++ b/core/fpdfapi/parser/cpdf_parser.cpp
@@ -32,10 +32,10 @@
 #include "core/fxcrt/fx_extension.h"
 #include "core/fxcrt/fx_safe_types.h"
 #include "core/fxcrt/scoped_set_insertion.h"
+#include "core/fxcrt/span.h"
 #include "third_party/base/check.h"
 #include "third_party/base/check_op.h"
 #include "third_party/base/containers/contains.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/notreached.h"
 
 using ObjectType = CPDF_CrossRefTable::ObjectType;
diff --git a/core/fpdfapi/parser/cpdf_simple_parser.h b/core/fpdfapi/parser/cpdf_simple_parser.h
index c953be6..2d7264e 100644
--- a/core/fpdfapi/parser/cpdf_simple_parser.h
+++ b/core/fpdfapi/parser/cpdf_simple_parser.h
@@ -10,7 +10,7 @@
 #include <stdint.h>
 
 #include "core/fxcrt/bytestring.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CPDF_SimpleParser {
  public:
diff --git a/core/fpdfapi/parser/cpdf_simple_parser_unittest.cpp b/core/fpdfapi/parser/cpdf_simple_parser_unittest.cpp
index 77483b3..c7f77c9 100644
--- a/core/fpdfapi/parser/cpdf_simple_parser_unittest.cpp
+++ b/core/fpdfapi/parser/cpdf_simple_parser_unittest.cpp
@@ -8,9 +8,9 @@
 
 #include "core/fpdfapi/parser/fpdf_parser_utility.h"
 #include "core/fxcrt/fx_memcpy_wrappers.h"
+#include "core/fxcrt/span.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/test_support.h"
-#include "third_party/base/containers/span.h"
 
 TEST(SimpleParserTest, GetWord) {
   static const pdfium::StrFuncTestData test_data[] = {
diff --git a/core/fpdfapi/parser/cpdf_stream_acc.h b/core/fpdfapi/parser/cpdf_stream_acc.h
index 74657dd..73db636 100644
--- a/core/fpdfapi/parser/cpdf_stream_acc.h
+++ b/core/fpdfapi/parser/cpdf_stream_acc.h
@@ -14,8 +14,8 @@
 #include "core/fxcrt/bytestring.h"
 #include "core/fxcrt/data_vector.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "third_party/abseil-cpp/absl/types/variant.h"
-#include "third_party/base/containers/span.h"
 
 class CPDF_Dictionary;
 class CPDF_Stream;
diff --git a/core/fpdfapi/parser/cpdf_syntax_parser.h b/core/fpdfapi/parser/cpdf_syntax_parser.h
index d3f5747..3a2103a 100644
--- a/core/fpdfapi/parser/cpdf_syntax_parser.h
+++ b/core/fpdfapi/parser/cpdf_syntax_parser.h
@@ -16,10 +16,10 @@
 #include "core/fxcrt/data_vector.h"
 #include "core/fxcrt/fx_types.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/string_pool_template.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "core/fxcrt/weak_ptr.h"
-#include "third_party/base/containers/span.h"
 
 class CPDF_Dictionary;
 class CPDF_IndirectObjectHolder;
diff --git a/core/fpdfapi/parser/fpdf_parser_decode.h b/core/fpdfapi/parser/fpdf_parser_decode.h
index b84da06..59f9f82 100644
--- a/core/fpdfapi/parser/fpdf_parser_decode.h
+++ b/core/fpdfapi/parser/fpdf_parser_decode.h
@@ -18,7 +18,7 @@
 #include "core/fxcrt/fx_memory_wrappers.h"
 #include "core/fxcrt/fx_string.h"
 #include "core/fxcrt/retain_ptr.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CPDF_Array;
 class CPDF_Dictionary;
diff --git a/core/fpdfapi/parser/fpdf_parser_decode_unittest.cpp b/core/fpdfapi/parser/fpdf_parser_decode_unittest.cpp
index cc9b6d9..e32b6aa 100644
--- a/core/fpdfapi/parser/fpdf_parser_decode_unittest.cpp
+++ b/core/fpdfapi/parser/fpdf_parser_decode_unittest.cpp
@@ -17,11 +17,11 @@
 #include "core/fpdfapi/parser/cpdf_string.h"
 #include "core/fxcrt/bytestring.h"
 #include "core/fxcrt/fx_memory_wrappers.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/string_view_template.h"
 #include "core/fxcrt/widestring.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/test_support.h"
-#include "third_party/base/containers/span.h"
 
 namespace {
 
diff --git a/core/fpdfapi/render/charposlist.h b/core/fpdfapi/render/charposlist.h
index 47c5d57..c320443 100644
--- a/core/fpdfapi/render/charposlist.h
+++ b/core/fpdfapi/render/charposlist.h
@@ -11,7 +11,7 @@
 
 #include <vector>
 
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CPDF_Font;
 class TextCharPos;
diff --git a/core/fpdfapi/render/cpdf_rendershading.cpp b/core/fpdfapi/render/cpdf_rendershading.cpp
index 8f4d6cb..4c61b83 100644
--- a/core/fpdfapi/render/cpdf_rendershading.cpp
+++ b/core/fpdfapi/render/cpdf_rendershading.cpp
@@ -26,6 +26,7 @@
 #include "core/fpdfapi/render/cpdf_renderoptions.h"
 #include "core/fxcrt/fx_safe_types.h"
 #include "core/fxcrt/fx_system.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/span_util.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "core/fxge/cfx_defaultrenderdevice.h"
@@ -35,7 +36,6 @@
 #include "core/fxge/dib/fx_dib.h"
 #include "third_party/base/check.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 
 namespace {
 
diff --git a/core/fpdfapi/render/cpdf_renderstatus.cpp b/core/fpdfapi/render/cpdf_renderstatus.cpp
index dadfcfc..02aa909 100644
--- a/core/fpdfapi/render/cpdf_renderstatus.cpp
+++ b/core/fpdfapi/render/cpdf_renderstatus.cpp
@@ -56,6 +56,7 @@
 #include "core/fxcrt/fx_2d_size.h"
 #include "core/fxcrt/fx_safe_types.h"
 #include "core/fxcrt/fx_system.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/span_util.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "core/fxge/cfx_defaultrenderdevice.h"
@@ -69,7 +70,6 @@
 #include "core/fxge/text_glyph_pos.h"
 #include "third_party/base/check.h"
 #include "third_party/base/containers/contains.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/notreached.h"
 
 namespace {
diff --git a/core/fpdfapi/render/cpdf_textrenderer.h b/core/fpdfapi/render/cpdf_textrenderer.h
index 857340f..1a5ecea 100644
--- a/core/fpdfapi/render/cpdf_textrenderer.h
+++ b/core/fpdfapi/render/cpdf_textrenderer.h
@@ -11,8 +11,8 @@
 
 #include "core/fxcrt/bytestring.h"
 #include "core/fxcrt/fx_coordinates.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/dib/fx_dib.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_RenderDevice;
 class CFX_GraphStateData;
diff --git a/core/fpdfdoc/cpdf_defaultappearance_unittest.cpp b/core/fpdfdoc/cpdf_defaultappearance_unittest.cpp
index ce08bf3..b3fb040 100644
--- a/core/fpdfdoc/cpdf_defaultappearance_unittest.cpp
+++ b/core/fpdfdoc/cpdf_defaultappearance_unittest.cpp
@@ -7,9 +7,9 @@
 #include <iterator>
 
 #include "core/fpdfapi/parser/cpdf_simple_parser.h"
+#include "core/fxcrt/span.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/test_support.h"
-#include "third_party/base/containers/span.h"
 
 TEST(CPDFDefaultAppearanceTest, FindTagParamFromStart) {
   static const struct FindTagTestStruct {
diff --git a/core/fpdfdoc/cpdf_interactiveform.h b/core/fpdfdoc/cpdf_interactiveform.h
index 3b6e4f1..4e5d18a 100644
--- a/core/fpdfdoc/cpdf_interactiveform.h
+++ b/core/fpdfdoc/cpdf_interactiveform.h
@@ -22,8 +22,8 @@
 #include "core/fxcrt/fx_coordinates.h"
 #include "core/fxcrt/fx_string.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
-#include "third_party/base/containers/span.h"
 
 class CFieldTree;
 class CFDF_Document;
diff --git a/core/fxcodec/BUILD.gn b/core/fxcodec/BUILD.gn
index 8f4feb7..588cd2d 100644
--- a/core/fxcodec/BUILD.gn
+++ b/core/fxcodec/BUILD.gn
@@ -73,12 +73,11 @@
     "../../:pdfium_strict_config",
     "../../:pdfium_noshorten_config",
   ]
-  public_deps = [ "../../third_party:pdfium_base" ]
+  public_deps = [ "../fxcrt" ]
   deps = [
     "../../third_party:lcms2",
     "../../third_party:libopenjpeg2",
     "../../third_party:zlib",
-    "../fxcrt",
     "../fxge",
     "//third_party:jpeg",
   ]
diff --git a/core/fxcodec/basic/basicmodule.h b/core/fxcodec/basic/basicmodule.h
index 61e3735..fbc1444 100644
--- a/core/fxcodec/basic/basicmodule.h
+++ b/core/fxcodec/basic/basicmodule.h
@@ -12,7 +12,7 @@
 #include <memory>
 
 #include "core/fxcrt/data_vector.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 namespace fxcodec {
 
diff --git a/core/fxcodec/bmp/bmp_decoder.h b/core/fxcodec/bmp/bmp_decoder.h
index 08a1638..d78e92c 100644
--- a/core/fxcodec/bmp/bmp_decoder.h
+++ b/core/fxcodec/bmp/bmp_decoder.h
@@ -13,7 +13,7 @@
 #include "core/fxcodec/progressive_decoder_iface.h"
 #include "core/fxcrt/fx_system.h"
 #include "core/fxcrt/retain_ptr.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 #ifndef PDF_ENABLE_XFA_BMP
 #error "BMP must be enabled"
diff --git a/core/fxcodec/bmp/cfx_bmpdecompressor.h b/core/fxcodec/bmp/cfx_bmpdecompressor.h
index 6432777..e5227a7 100644
--- a/core/fxcodec/bmp/cfx_bmpdecompressor.h
+++ b/core/fxcodec/bmp/cfx_bmpdecompressor.h
@@ -15,8 +15,8 @@
 #include "core/fxcodec/bmp/fx_bmp.h"
 #include "core/fxcrt/data_vector.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_CodecMemory;
 
diff --git a/core/fxcodec/cfx_codec_memory.h b/core/fxcodec/cfx_codec_memory.h
index 2076311..23ca0d7 100644
--- a/core/fxcodec/cfx_codec_memory.h
+++ b/core/fxcodec/cfx_codec_memory.h
@@ -9,7 +9,7 @@
 
 #include "core/fxcrt/fx_memory_wrappers.h"
 #include "core/fxcrt/retain_ptr.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CFX_CodecMemory final : public Retainable {
  public:
diff --git a/core/fxcodec/fax/faxmodule.cpp b/core/fxcodec/fax/faxmodule.cpp
index 60a7786..f0b84bc 100644
--- a/core/fxcodec/fax/faxmodule.cpp
+++ b/core/fxcodec/fax/faxmodule.cpp
@@ -19,11 +19,11 @@
 #include "core/fxcrt/data_vector.h"
 #include "core/fxcrt/fx_2d_size.h"
 #include "core/fxcrt/fx_memory.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/span_util.h"
 #include "core/fxge/calculate_pitch.h"
 #include "third_party/base/check.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/numerics/safe_conversions.h"
 
 #if BUILDFLAG(IS_WIN)
diff --git a/core/fxcodec/fax/faxmodule.h b/core/fxcodec/fax/faxmodule.h
index acc62d8..aa03552 100644
--- a/core/fxcodec/fax/faxmodule.h
+++ b/core/fxcodec/fax/faxmodule.h
@@ -12,7 +12,7 @@
 #include <memory>
 
 #include "build/build_config.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 #if BUILDFLAG(IS_WIN)
 #include "core/fxcrt/data_vector.h"
diff --git a/core/fxcodec/flate/flatemodule.cpp b/core/fxcodec/flate/flatemodule.cpp
index c973094..bf3c359 100644
--- a/core/fxcodec/flate/flatemodule.cpp
+++ b/core/fxcodec/flate/flatemodule.cpp
@@ -21,10 +21,10 @@
 #include "core/fxcrt/fx_extension.h"
 #include "core/fxcrt/fx_memory_wrappers.h"
 #include "core/fxcrt/fx_safe_types.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/span_util.h"
 #include "core/fxge/calculate_pitch.h"
 #include "third_party/base/check.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/notreached.h"
 #include "third_party/base/numerics/safe_conversions.h"
 
diff --git a/core/fxcodec/flate/flatemodule.h b/core/fxcodec/flate/flatemodule.h
index f5a9509..ae581df 100644
--- a/core/fxcodec/flate/flatemodule.h
+++ b/core/fxcodec/flate/flatemodule.h
@@ -13,7 +13,7 @@
 
 #include "core/fxcrt/data_vector.h"
 #include "core/fxcrt/fx_memory_wrappers.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 namespace fxcodec {
 
diff --git a/core/fxcodec/gif/cfx_gifcontext.h b/core/fxcodec/gif/cfx_gifcontext.h
index e4d89c0..57d796c 100644
--- a/core/fxcodec/gif/cfx_gifcontext.h
+++ b/core/fxcodec/gif/cfx_gifcontext.h
@@ -14,8 +14,8 @@
 #include "core/fxcodec/gif/gif_decoder.h"
 #include "core/fxcodec/gif/lzw_decompressor.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_CodecMemory;
 
diff --git a/core/fxcodec/gif/gif_decoder.h b/core/fxcodec/gif/gif_decoder.h
index 1e2d39a..988e704 100644
--- a/core/fxcodec/gif/gif_decoder.h
+++ b/core/fxcodec/gif/gif_decoder.h
@@ -13,7 +13,7 @@
 #include "core/fxcodec/gif/cfx_gif.h"
 #include "core/fxcodec/progressive_decoder_iface.h"
 #include "core/fxcrt/fx_coordinates.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 #ifndef PDF_ENABLE_XFA_GIF
 #error "GIF must be enabled"
diff --git a/core/fxcodec/icc/icc_transform.h b/core/fxcodec/icc/icc_transform.h
index 53d6adb..1b8811d 100644
--- a/core/fxcodec/icc/icc_transform.h
+++ b/core/fxcodec/icc/icc_transform.h
@@ -12,7 +12,7 @@
 #include <memory>
 
 #include "core/fxcodec/fx_codec_def.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 #if defined(USE_SYSTEM_LCMS2)
 #include <lcms2.h>
diff --git a/core/fxcodec/jbig2/JBig2_BitStream.h b/core/fxcodec/jbig2/JBig2_BitStream.h
index 0a3a44d..f6e2541 100644
--- a/core/fxcodec/jbig2/JBig2_BitStream.h
+++ b/core/fxcodec/jbig2/JBig2_BitStream.h
@@ -8,7 +8,7 @@
 #define CORE_FXCODEC_JBIG2_JBIG2_BITSTREAM_H_
 
 #include "core/fxcrt/retain_ptr.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CJBig2_BitStream {
  public:
diff --git a/core/fxcodec/jbig2/JBig2_Context.h b/core/fxcodec/jbig2/JBig2_Context.h
index 5572eb7..945eeed 100644
--- a/core/fxcodec/jbig2/JBig2_Context.h
+++ b/core/fxcodec/jbig2/JBig2_Context.h
@@ -16,8 +16,8 @@
 #include "core/fxcodec/jbig2/JBig2_DocumentContext.h"
 #include "core/fxcodec/jbig2/JBig2_Page.h"
 #include "core/fxcodec/jbig2/JBig2_Segment.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
-#include "third_party/base/containers/span.h"
 
 class CJBig2_ArithDecoder;
 class CJBig2_GRDProc;
diff --git a/core/fxcodec/jbig2/JBig2_Image.h b/core/fxcodec/jbig2/JBig2_Image.h
index 1fe8402..9b9a136 100644
--- a/core/fxcodec/jbig2/JBig2_Image.h
+++ b/core/fxcodec/jbig2/JBig2_Image.h
@@ -12,7 +12,7 @@
 #include "core/fxcodec/jbig2/JBig2_Define.h"
 #include "core/fxcrt/fx_memory_wrappers.h"
 #include "core/fxcrt/maybe_owned.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 struct FX_RECT;
 
diff --git a/core/fxcodec/jbig2/JBig2_SddProc.h b/core/fxcodec/jbig2/JBig2_SddProc.h
index a1e7590..d8fd50b 100644
--- a/core/fxcodec/jbig2/JBig2_SddProc.h
+++ b/core/fxcodec/jbig2/JBig2_SddProc.h
@@ -13,9 +13,9 @@
 #include <vector>
 
 #include "core/fxcodec/jbig2/JBig2_ArithDecoder.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "core/fxcrt/unowned_ptr_exclusion.h"
-#include "third_party/base/containers/span.h"
 
 class CJBig2_BitStream;
 class CJBig2_HuffmanTable;
diff --git a/core/fxcodec/jbig2/jbig2_decoder.h b/core/fxcodec/jbig2/jbig2_decoder.h
index 745fa2e..868f1d1 100644
--- a/core/fxcodec/jbig2/jbig2_decoder.h
+++ b/core/fxcodec/jbig2/jbig2_decoder.h
@@ -10,8 +10,8 @@
 #include <memory>
 
 #include "core/fxcodec/fx_codec_def.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr_exclusion.h"
-#include "third_party/base/containers/span.h"
 
 class CJBig2_Context;
 class JBig2_DocumentContext;
diff --git a/core/fxcodec/jpeg/jpegmodule.h b/core/fxcodec/jpeg/jpegmodule.h
index 80dd406..dc132fc 100644
--- a/core/fxcodec/jpeg/jpegmodule.h
+++ b/core/fxcodec/jpeg/jpegmodule.h
@@ -13,7 +13,7 @@
 #include <optional>
 
 #include "build/build_config.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 #if BUILDFLAG(IS_WIN)
 #include "core/fxcrt/retain_ptr.h"
diff --git a/core/fxcodec/jpx/cjpx_decoder.h b/core/fxcodec/jpx/cjpx_decoder.h
index c6e67c8..f4db416 100644
--- a/core/fxcodec/jpx/cjpx_decoder.h
+++ b/core/fxcodec/jpx/cjpx_decoder.h
@@ -11,8 +11,8 @@
 
 #include <memory>
 
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
-#include "third_party/base/containers/span.h"
 
 #if defined(USE_SYSTEM_LIBOPENJPEG2)
 #include <openjpeg.h>
diff --git a/core/fxcodec/progressive_decoder.h b/core/fxcodec/progressive_decoder.h
index 1d9e9e8..5f8b3e8 100644
--- a/core/fxcodec/progressive_decoder.h
+++ b/core/fxcodec/progressive_decoder.h
@@ -18,10 +18,10 @@
 #include "core/fxcodec/progressive_decoder_iface.h"
 #include "core/fxcrt/data_vector.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr_exclusion.h"
 #include "core/fxge/dib/cstretchengine.h"
 #include "core/fxge/dib/fx_dib.h"
-#include "third_party/base/containers/span.h"
 
 #ifdef PDF_ENABLE_XFA_BMP
 #include "core/fxcodec/bmp/bmp_decoder.h"
diff --git a/core/fxcodec/progressive_decoder_unittest.cpp b/core/fxcodec/progressive_decoder_unittest.cpp
index 682cd19..1e3302a 100644
--- a/core/fxcodec/progressive_decoder_unittest.cpp
+++ b/core/fxcodec/progressive_decoder_unittest.cpp
@@ -19,11 +19,11 @@
 #include "core/fxcrt/cfx_read_only_vector_stream.h"
 #include "core/fxcrt/data_vector.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/dib/cfx_dibitmap.h"
 #include "core/fxge/dib/fx_dib.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
-#include "third_party/base/containers/span.h"
 
 #ifdef PDF_ENABLE_XFA_BMP
 #include "core/fxcodec/bmp/bmp_decoder.h"
diff --git a/core/fxcodec/scanlinedecoder.h b/core/fxcodec/scanlinedecoder.h
index f319147..482a279 100644
--- a/core/fxcodec/scanlinedecoder.h
+++ b/core/fxcodec/scanlinedecoder.h
@@ -9,7 +9,7 @@
 
 #include <stdint.h>
 
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class PauseIndicatorIface;
 
diff --git a/core/fxcrt/BUILD.gn b/core/fxcrt/BUILD.gn
index c05196f..31d3fd6 100644
--- a/core/fxcrt/BUILD.gn
+++ b/core/fxcrt/BUILD.gn
@@ -15,6 +15,7 @@
     "../../fxjs:*",
     "../../testing:*",
     "../../testing/fuzzers/*",
+    "../../testing/image_diff/*",
     "../../third_party:fx_agg",
     "../../third_party:fx_lcms2",
     "../../third_party:fx_libopenjpeg",
@@ -85,6 +86,7 @@
     "retain_ptr.h",
     "scoped_set_insertion.h",
     "shared_copy_on_write.h",
+    "span.h",
     "span_util.h",
     "stl_util.h",
     "string_data_template.cpp",
diff --git a/core/fxcrt/binary_buffer.h b/core/fxcrt/binary_buffer.h
index 26f0caf..acae9cb 100644
--- a/core/fxcrt/binary_buffer.h
+++ b/core/fxcrt/binary_buffer.h
@@ -12,7 +12,7 @@
 
 #include "core/fxcrt/bytestring.h"
 #include "core/fxcrt/data_vector.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 namespace fxcrt {
 
diff --git a/core/fxcrt/byteorder.h b/core/fxcrt/byteorder.h
index 24dd059..8db9b65 100644
--- a/core/fxcrt/byteorder.h
+++ b/core/fxcrt/byteorder.h
@@ -8,7 +8,7 @@
 #include <stdint.h>
 
 #include "build/build_config.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 #if defined(COMPILER_MSVC)
 #include <stdlib.h>
diff --git a/core/fxcrt/bytestring.cpp b/core/fxcrt/bytestring.cpp
index fba02a8..716620f 100644
--- a/core/fxcrt/bytestring.cpp
+++ b/core/fxcrt/bytestring.cpp
@@ -19,11 +19,11 @@
 #include "core/fxcrt/fx_memcpy_wrappers.h"
 #include "core/fxcrt/fx_safe_types.h"
 #include "core/fxcrt/fx_system.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/span_util.h"
 #include "core/fxcrt/string_pool_template.h"
 #include "third_party/base/check.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 
 // Instantiate.
 template class fxcrt::StringViewTemplate<char>;
diff --git a/core/fxcrt/bytestring.h b/core/fxcrt/bytestring.h
index 52894cb..d6867be 100644
--- a/core/fxcrt/bytestring.h
+++ b/core/fxcrt/bytestring.h
@@ -20,11 +20,11 @@
 
 #include "core/fxcrt/fx_string_wrappers.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/string_data_template.h"
 #include "core/fxcrt/string_template.h"
 #include "core/fxcrt/string_view_template.h"
 #include "third_party/base/check.h"
-#include "third_party/base/containers/span.h"
 
 namespace fxcrt {
 
diff --git a/core/fxcrt/bytestring_unittest.cpp b/core/fxcrt/bytestring_unittest.cpp
index ae6a02c..7b086f0 100644
--- a/core/fxcrt/bytestring_unittest.cpp
+++ b/core/fxcrt/bytestring_unittest.cpp
@@ -13,9 +13,9 @@
 #include <vector>
 
 #include "core/fxcrt/fx_string.h"
+#include "core/fxcrt/span.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/base/containers/contains.h"
-#include "third_party/base/containers/span.h"
 
 namespace fxcrt {
 
diff --git a/core/fxcrt/cfx_bitstream.h b/core/fxcrt/cfx_bitstream.h
index 8e168b8..186b79a 100644
--- a/core/fxcrt/cfx_bitstream.h
+++ b/core/fxcrt/cfx_bitstream.h
@@ -10,7 +10,7 @@
 #include <stddef.h>
 #include <stdint.h>
 
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CFX_BitStream {
  public:
diff --git a/core/fxcrt/cfx_datetime.cpp b/core/fxcrt/cfx_datetime.cpp
index 526bba4..4a0ea2f 100644
--- a/core/fxcrt/cfx_datetime.cpp
+++ b/core/fxcrt/cfx_datetime.cpp
@@ -9,8 +9,8 @@
 #include "build/build_config.h"
 #include "core/fxcrt/fx_extension.h"
 #include "core/fxcrt/fx_system.h"
+#include "core/fxcrt/span.h"
 #include "third_party/base/check.h"
-#include "third_party/base/containers/span.h"
 
 namespace {
 
diff --git a/core/fxcrt/cfx_memorystream.h b/core/fxcrt/cfx_memorystream.h
index b2620fc..1709589 100644
--- a/core/fxcrt/cfx_memorystream.h
+++ b/core/fxcrt/cfx_memorystream.h
@@ -10,7 +10,7 @@
 #include "core/fxcrt/data_vector.h"
 #include "core/fxcrt/fx_stream.h"
 #include "core/fxcrt/retain_ptr.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CFX_MemoryStream final : public IFX_SeekableStream {
  public:
diff --git a/core/fxcrt/cfx_read_only_span_stream.h b/core/fxcrt/cfx_read_only_span_stream.h
index d476640..5b786b2 100644
--- a/core/fxcrt/cfx_read_only_span_stream.h
+++ b/core/fxcrt/cfx_read_only_span_stream.h
@@ -9,7 +9,7 @@
 
 #include "core/fxcrt/fx_stream.h"
 #include "core/fxcrt/retain_ptr.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CFX_ReadOnlySpanStream final : public IFX_SeekableReadStream {
  public:
diff --git a/core/fxcrt/cfx_read_only_string_stream.cpp b/core/fxcrt/cfx_read_only_string_stream.cpp
index 364330b..5967ed8 100644
--- a/core/fxcrt/cfx_read_only_string_stream.cpp
+++ b/core/fxcrt/cfx_read_only_string_stream.cpp
@@ -7,7 +7,7 @@
 #include <utility>
 
 #include "core/fxcrt/cfx_read_only_span_stream.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 CFX_ReadOnlyStringStream::CFX_ReadOnlyStringStream(ByteString data)
     : data_(std::move(data)),
diff --git a/core/fxcrt/cfx_read_only_vector_stream.cpp b/core/fxcrt/cfx_read_only_vector_stream.cpp
index f1120bb..87e742d 100644
--- a/core/fxcrt/cfx_read_only_vector_stream.cpp
+++ b/core/fxcrt/cfx_read_only_vector_stream.cpp
@@ -7,7 +7,7 @@
 #include <utility>
 
 #include "core/fxcrt/cfx_read_only_span_stream.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 CFX_ReadOnlyVectorStream::CFX_ReadOnlyVectorStream(DataVector<uint8_t> data)
     : data_(std::move(data)),
diff --git a/core/fxcrt/cfx_seekablestreamproxy_unittest.cpp b/core/fxcrt/cfx_seekablestreamproxy_unittest.cpp
index aee35bc..df5abaa 100644
--- a/core/fxcrt/cfx_seekablestreamproxy_unittest.cpp
+++ b/core/fxcrt/cfx_seekablestreamproxy_unittest.cpp
@@ -8,8 +8,8 @@
 
 #include "core/fxcrt/cfx_read_only_span_stream.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "testing/gtest/include/gtest/gtest.h"
-#include "third_party/base/containers/span.h"
 
 TEST(SeekableStreamProxyTest, NullStream) {
   auto proxy_stream = pdfium::MakeRetain<CFX_SeekableStreamProxy>(
diff --git a/core/fxcrt/fixed_size_data_vector.h b/core/fxcrt/fixed_size_data_vector.h
index 769ac9c..4da7046 100644
--- a/core/fxcrt/fixed_size_data_vector.h
+++ b/core/fxcrt/fixed_size_data_vector.h
@@ -11,7 +11,7 @@
 #include <utility>
 
 #include "core/fxcrt/fx_memory_wrappers.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 namespace fxcrt {
 
diff --git a/core/fxcrt/fixed_size_data_vector_unittest.cpp b/core/fxcrt/fixed_size_data_vector_unittest.cpp
index 80e3bab..546ef37 100644
--- a/core/fxcrt/fixed_size_data_vector_unittest.cpp
+++ b/core/fxcrt/fixed_size_data_vector_unittest.cpp
@@ -8,10 +8,10 @@
 #include <numeric>
 #include <utility>
 
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/span_util.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
-#include "third_party/base/containers/span.h"
 
 TEST(FixedSizedDataVector, NoData) {
   FixedSizeDataVector<int> vec;
diff --git a/core/fxcrt/fx_codepage.h b/core/fxcrt/fx_codepage.h
index 2aa7741..8368d37 100644
--- a/core/fxcrt/fx_codepage.h
+++ b/core/fxcrt/fx_codepage.h
@@ -12,8 +12,8 @@
 // Prove consistency with incomplete forward definitions.
 #include "core/fxcrt/fx_codepage_forward.h"
 #include "core/fxcrt/fx_string.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr_exclusion.h"
-#include "third_party/base/containers/span.h"
 
 enum class FX_CodePage : uint16_t {
   kDefANSI = 0,
diff --git a/core/fxcrt/fx_coordinates.h b/core/fxcrt/fx_coordinates.h
index f6b2347..49108ad 100644
--- a/core/fxcrt/fx_coordinates.h
+++ b/core/fxcrt/fx_coordinates.h
@@ -13,7 +13,7 @@
 #include <iosfwd>
 #endif
 
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 template <class BaseType>
 class CFX_PTemplate {
diff --git a/core/fxcrt/fx_random.h b/core/fxcrt/fx_random.h
index 635e8cc..98bed83 100644
--- a/core/fxcrt/fx_random.h
+++ b/core/fxcrt/fx_random.h
@@ -9,7 +9,7 @@
 
 #include <stdint.h>
 
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 void* FX_Random_MT_Start(uint32_t dwSeed);
 void FX_Random_MT_Close(void* pContext);
diff --git a/core/fxcrt/fx_stream.h b/core/fxcrt/fx_stream.h
index 15e02d5..e9caeb7 100644
--- a/core/fxcrt/fx_stream.h
+++ b/core/fxcrt/fx_stream.h
@@ -13,7 +13,7 @@
 #include "core/fxcrt/bytestring.h"
 #include "core/fxcrt/fx_types.h"
 #include "core/fxcrt/retain_ptr.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class IFX_WriteStream {
  public:
diff --git a/core/fxcrt/fx_string.cpp b/core/fxcrt/fx_string.cpp
index 867aadc..b6bdb5a 100644
--- a/core/fxcrt/fx_string.cpp
+++ b/core/fxcrt/fx_string.cpp
@@ -14,12 +14,12 @@
 #include "core/fxcrt/bytestring.h"
 #include "core/fxcrt/code_point_view.h"
 #include "core/fxcrt/fx_extension.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/span_util.h"
 #include "core/fxcrt/string_view_template.h"
 #include "core/fxcrt/utf16.h"
 #include "core/fxcrt/widestring.h"
 #include "third_party/base/compiler_specific.h"
-#include "third_party/base/containers/span.h"
 
 #if !defined(WCHAR_T_IS_16_BIT) && !defined(WCHAR_T_IS_32_BIT)
 #error "Unknown wchar_t size"
diff --git a/core/fxcrt/fx_string.h b/core/fxcrt/fx_string.h
index c714eb3..3485a80 100644
--- a/core/fxcrt/fx_string.h
+++ b/core/fxcrt/fx_string.h
@@ -13,8 +13,8 @@
 #include <vector>
 
 #include "core/fxcrt/bytestring.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/widestring.h"
-#include "third_party/base/containers/span.h"
 
 constexpr uint32_t FXBSTR_ID(uint8_t c1, uint8_t c2, uint8_t c3, uint8_t c4) {
   return static_cast<uint32_t>(c1) << 24 | static_cast<uint32_t>(c2) << 16 |
diff --git a/core/fxcrt/fx_string_unittest.cpp b/core/fxcrt/fx_string_unittest.cpp
index 2998658..b1227f7 100644
--- a/core/fxcrt/fx_string_unittest.cpp
+++ b/core/fxcrt/fx_string_unittest.cpp
@@ -6,9 +6,9 @@
 
 #include "build/build_config.h"
 #include "core/fxcrt/fx_string.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/utf16.h"
 #include "testing/gtest/include/gtest/gtest.h"
-#include "third_party/base/containers/span.h"
 
 char* TerminatedFloatToString(float value, pdfium::span<char> buf) {
   size_t buflen = FloatToString(value, buf);
diff --git a/core/fxcrt/pdfium_span_unittest.cpp b/core/fxcrt/pdfium_span_unittest.cpp
index 9f1134d..0228fb2 100644
--- a/core/fxcrt/pdfium_span_unittest.cpp
+++ b/core/fxcrt/pdfium_span_unittest.cpp
@@ -4,9 +4,9 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "testing/gtest/include/gtest/gtest.h"
-#include "third_party/base/containers/span.h"
 
 // Tests PDFium-modifications to base::span. The name of this file is
 // chosen to avoid collisions with base's span_unittest.cc
diff --git a/third_party/base/containers/span.h b/core/fxcrt/span.h
similarity index 98%
rename from third_party/base/containers/span.h
rename to core/fxcrt/span.h
index 2c8b90e..ab21ad6 100644
--- a/third_party/base/containers/span.h
+++ b/core/fxcrt/span.h
@@ -1,9 +1,9 @@
-// Copyright 2017 The Chromium Authors. All rights reserved.
+// Copyright 2024 The PDFium Authors
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef THIRD_PARTY_BASE_CONTAINERS_SPAN_H_
-#define THIRD_PARTY_BASE_CONTAINERS_SPAN_H_
+#ifndef CORE_FXCRT_SPAN_H_
+#define CORE_FXCRT_SPAN_H_
 
 #include <stddef.h>
 #include <stdint.h>
@@ -402,4 +402,4 @@
 
 }  // namespace pdfium
 
-#endif  // THIRD_PARTY_BASE_CONTAINERS_SPAN_H_
+#endif  // CORE_FXCRT_SPAN_H_
diff --git a/core/fxcrt/span_util.h b/core/fxcrt/span_util.h
index a88532a..0d6d198 100644
--- a/core/fxcrt/span_util.h
+++ b/core/fxcrt/span_util.h
@@ -11,8 +11,8 @@
 #include <type_traits>
 
 #include "core/fxcrt/fx_memcpy_wrappers.h"
+#include "core/fxcrt/span.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 
 namespace fxcrt {
 
diff --git a/core/fxcrt/string_data_template.h b/core/fxcrt/string_data_template.h
index d2661a3..97c28cb 100644
--- a/core/fxcrt/string_data_template.h
+++ b/core/fxcrt/string_data_template.h
@@ -11,7 +11,7 @@
 #include <stdint.h>
 
 #include "core/fxcrt/retain_ptr.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 namespace fxcrt {
 
diff --git a/core/fxcrt/string_template.cpp b/core/fxcrt/string_template.cpp
index bb7328d..7d22f46 100644
--- a/core/fxcrt/string_template.cpp
+++ b/core/fxcrt/string_template.cpp
@@ -9,10 +9,10 @@
 #include <algorithm>
 #include <utility>
 
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/span_util.h"
 #include "third_party/base/check.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 
 namespace fxcrt {
 
diff --git a/core/fxcrt/string_view_template.h b/core/fxcrt/string_view_template.h
index 62ff237..09a529b 100644
--- a/core/fxcrt/string_view_template.h
+++ b/core/fxcrt/string_view_template.h
@@ -16,7 +16,7 @@
 
 #include "core/fxcrt/fx_memcpy_wrappers.h"
 #include "core/fxcrt/fx_system.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 namespace fxcrt {
 
diff --git a/core/fxcrt/widestring.h b/core/fxcrt/widestring.h
index 0e6feeb..22a821f 100644
--- a/core/fxcrt/widestring.h
+++ b/core/fxcrt/widestring.h
@@ -19,11 +19,11 @@
 #include <utility>
 
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/string_data_template.h"
 #include "core/fxcrt/string_template.h"
 #include "core/fxcrt/string_view_template.h"
 #include "third_party/base/check.h"
-#include "third_party/base/containers/span.h"
 
 namespace fxcrt {
 
diff --git a/core/fxcrt/widestring_unittest.cpp b/core/fxcrt/widestring_unittest.cpp
index 90161c2..f077516 100644
--- a/core/fxcrt/widestring_unittest.cpp
+++ b/core/fxcrt/widestring_unittest.cpp
@@ -10,10 +10,10 @@
 
 #include "build/build_config.h"
 #include "core/fxcrt/fx_string.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/utf16.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/base/containers/contains.h"
-#include "third_party/base/containers/span.h"
 
 namespace fxcrt {
 
diff --git a/core/fxcrt/widetext_buffer.h b/core/fxcrt/widetext_buffer.h
index 5c29a0b..0961e89 100644
--- a/core/fxcrt/widetext_buffer.h
+++ b/core/fxcrt/widetext_buffer.h
@@ -11,7 +11,7 @@
 
 #include "core/fxcrt/binary_buffer.h"
 #include "core/fxcrt/fx_string.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 namespace fxcrt {
 
diff --git a/core/fxge/agg/fx_agg_driver.cpp b/core/fxge/agg/fx_agg_driver.cpp
index a380a78..f962de0 100644
--- a/core/fxge/agg/fx_agg_driver.cpp
+++ b/core/fxge/agg/fx_agg_driver.cpp
@@ -15,6 +15,7 @@
 #include "build/build_config.h"
 #include "core/fxcrt/fx_2d_size.h"
 #include "core/fxcrt/fx_safe_types.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr_exclusion.h"
 #include "core/fxge/cfx_cliprgn.h"
 #include "core/fxge/cfx_defaultrenderdevice.h"
@@ -25,7 +26,6 @@
 #include "core/fxge/dib/cfx_imagestretcher.h"
 #include "third_party/base/check.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/notreached.h"
 
 // Ignore fallthrough warnings in agg23 headers.
diff --git a/core/fxge/android/cfpf_skiafont.h b/core/fxge/android/cfpf_skiafont.h
index 82045e9..01be9a2 100644
--- a/core/fxge/android/cfpf_skiafont.h
+++ b/core/fxge/android/cfpf_skiafont.h
@@ -12,9 +12,9 @@
 #include "core/fxcrt/bytestring.h"
 #include "core/fxcrt/fx_codepage_forward.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "core/fxge/cfx_face.h"
-#include "third_party/base/containers/span.h"
 
 class CFPF_SkiaFontMgr;
 class CFPF_SkiaPathFont;
diff --git a/core/fxge/android/cfx_androidfontinfo.h b/core/fxge/android/cfx_androidfontinfo.h
index 54500ba..3886f70 100644
--- a/core/fxge/android/cfx_androidfontinfo.h
+++ b/core/fxge/android/cfx_androidfontinfo.h
@@ -9,10 +9,10 @@
 
 #include <stdint.h>
 
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "core/fxge/cfx_fontmapper.h"
 #include "core/fxge/systemfontinfo_iface.h"
-#include "third_party/base/containers/span.h"
 
 class CFPF_SkiaFontMgr;
 
diff --git a/core/fxge/apple/fx_apple_impl.cpp b/core/fxge/apple/fx_apple_impl.cpp
index 935c33f..8fbe203 100644
--- a/core/fxge/apple/fx_apple_impl.cpp
+++ b/core/fxge/apple/fx_apple_impl.cpp
@@ -11,6 +11,7 @@
 
 #include "core/fxcrt/data_vector.h"
 #include "core/fxcrt/fx_system.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/agg/fx_agg_driver.h"
 #include "core/fxge/apple/fx_apple_platform.h"
 #include "core/fxge/cfx_cliprgn.h"
@@ -22,7 +23,6 @@
 #include "core/fxge/cfx_substfont.h"
 #include "core/fxge/dib/cfx_dibitmap.h"
 #include "core/fxge/text_char_pos.h"
-#include "third_party/base/containers/span.h"
 
 namespace {
 
diff --git a/core/fxge/apple/fx_quartz_device.h b/core/fxge/apple/fx_quartz_device.h
index 97080e3..14b6d58 100644
--- a/core/fxge/apple/fx_quartz_device.h
+++ b/core/fxge/apple/fx_quartz_device.h
@@ -11,8 +11,8 @@
 #include <stdint.h>
 
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/dib/fx_dib.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_DIBitmap;
 class CFX_Matrix;
diff --git a/core/fxge/cfx_face.h b/core/fxge/cfx_face.h
index 1cba75f..ffbec18 100644
--- a/core/fxge/cfx_face.h
+++ b/core/fxge/cfx_face.h
@@ -17,8 +17,8 @@
 #include "core/fxcrt/fx_coordinates.h"
 #include "core/fxcrt/observed_ptr.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/freetype/fx_freetype.h"
-#include "third_party/base/containers/span.h"
 
 namespace fxge {
 enum class FontEncoding : uint32_t;
diff --git a/core/fxge/cfx_font.cpp b/core/fxge/cfx_font.cpp
index 98ab8ea..ba3073b 100644
--- a/core/fxge/cfx_font.cpp
+++ b/core/fxge/cfx_font.cpp
@@ -17,6 +17,7 @@
 #include "core/fxcrt/data_vector.h"
 #include "core/fxcrt/fx_codepage.h"
 #include "core/fxcrt/fx_stream.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "core/fxge/cfx_fontcache.h"
 #include "core/fxge/cfx_fontmapper.h"
@@ -28,7 +29,6 @@
 #include "core/fxge/fx_font.h"
 #include "core/fxge/scoped_font_transform.h"
 #include "third_party/base/check.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/numerics/safe_conversions.h"
 
 namespace {
diff --git a/core/fxge/cfx_font.h b/core/fxge/cfx_font.h
index 6db9a1f..37bf6d2 100644
--- a/core/fxge/cfx_font.h
+++ b/core/fxge/cfx_font.h
@@ -18,10 +18,10 @@
 #include "core/fxcrt/fx_codepage_forward.h"
 #include "core/fxcrt/fx_coordinates.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr_exclusion.h"
 #include "core/fxge/cfx_face.h"
 #include "core/fxge/freetype/fx_freetype.h"
-#include "third_party/base/containers/span.h"
 
 #if defined(PDF_USE_SKIA)
 #include "core/fxge/fx_font.h"
diff --git a/core/fxge/cfx_fontmgr.h b/core/fxge/cfx_fontmgr.h
index c90b7c0..0086d48 100644
--- a/core/fxge/cfx_fontmgr.h
+++ b/core/fxge/cfx_fontmgr.h
@@ -18,9 +18,9 @@
 #include "core/fxcrt/fixed_size_data_vector.h"
 #include "core/fxcrt/observed_ptr.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/cfx_face.h"
 #include "core/fxge/freetype/fx_freetype.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_FontMapper;
 
diff --git a/core/fxge/cfx_gemodule.h b/core/fxge/cfx_gemodule.h
index f6846ce..47d0a95 100644
--- a/core/fxge/cfx_gemodule.h
+++ b/core/fxge/cfx_gemodule.h
@@ -15,7 +15,7 @@
 #include "core/fxcrt/unowned_ptr_exclusion.h"
 
 #if BUILDFLAG(IS_APPLE)
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 #endif
 
 class CFX_FontCache;
diff --git a/core/fxge/cfx_renderdevice.cpp b/core/fxge/cfx_renderdevice.cpp
index 8e96719..5c64dcc 100644
--- a/core/fxge/cfx_renderdevice.cpp
+++ b/core/fxge/cfx_renderdevice.cpp
@@ -14,6 +14,7 @@
 
 #include "build/build_config.h"
 #include "core/fxcrt/fx_safe_types.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/cfx_color.h"
 #include "core/fxge/cfx_defaultrenderdevice.h"
 #include "core/fxge/cfx_fillrenderoptions.h"
@@ -33,7 +34,6 @@
 #include "core/fxge/text_glyph_pos.h"
 #include "third_party/base/check.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 
 #if defined(PDF_USE_SKIA)
 #include "third_party/skia/include/core/SkTypes.h"  // nogncheck
diff --git a/core/fxge/cfx_renderdevice.h b/core/fxge/cfx_renderdevice.h
index c4495ad..de0a84b 100644
--- a/core/fxge/cfx_renderdevice.h
+++ b/core/fxge/cfx_renderdevice.h
@@ -13,12 +13,12 @@
 #include "build/build_config.h"
 #include "core/fxcrt/fx_coordinates.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "core/fxge/cfx_path.h"
 #include "core/fxge/dib/fx_dib.h"
 #include "core/fxge/render_defines.h"
 #include "core/fxge/renderdevicedriver_iface.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_DIBBase;
 class CFX_DIBitmap;
diff --git a/core/fxge/dib/cfx_bitmapstorer.h b/core/fxge/dib/cfx_bitmapstorer.h
index 326a8b0..ee75ccc 100644
--- a/core/fxge/dib/cfx_bitmapstorer.h
+++ b/core/fxge/dib/cfx_bitmapstorer.h
@@ -8,8 +8,8 @@
 #define CORE_FXGE_DIB_CFX_BITMAPSTORER_H_
 
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/dib/scanlinecomposer_iface.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_DIBitmap;
 
diff --git a/core/fxge/dib/cfx_dibbase.cpp b/core/fxge/dib/cfx_dibbase.cpp
index 8601275..cf6ce6a 100644
--- a/core/fxge/dib/cfx_dibbase.cpp
+++ b/core/fxge/dib/cfx_dibbase.cpp
@@ -18,6 +18,7 @@
 #include "core/fxcrt/fx_coordinates.h"
 #include "core/fxcrt/fx_memory.h"
 #include "core/fxcrt/fx_safe_types.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/span_util.h"
 #include "core/fxge/calculate_pitch.h"
 #include "core/fxge/cfx_cliprgn.h"
@@ -27,7 +28,6 @@
 #include "core/fxge/dib/cfx_imagetransformer.h"
 #include "third_party/base/check.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/notreached.h"
 
 namespace {
diff --git a/core/fxge/dib/cfx_dibbase.h b/core/fxge/dib/cfx_dibbase.h
index 8c4ceab..bbfecdb 100644
--- a/core/fxge/dib/cfx_dibbase.h
+++ b/core/fxge/dib/cfx_dibbase.h
@@ -12,8 +12,8 @@
 #include "build/build_config.h"
 #include "core/fxcrt/data_vector.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/dib/fx_dib.h"
-#include "third_party/base/containers/span.h"
 
 #if defined(PDF_USE_SKIA)
 #include "third_party/skia/include/core/SkRefCnt.h"  // nogncheck
diff --git a/core/fxge/dib/cfx_dibitmap.h b/core/fxge/dib/cfx_dibitmap.h
index c1444d1..858f7ab 100644
--- a/core/fxge/dib/cfx_dibitmap.h
+++ b/core/fxge/dib/cfx_dibitmap.h
@@ -12,9 +12,9 @@
 #include "core/fxcrt/fx_memory_wrappers.h"
 #include "core/fxcrt/maybe_owned.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/dib/cfx_dibbase.h"
 #include "core/fxge/dib/fx_dib.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_DIBitmap final : public CFX_DIBBase {
  public:
diff --git a/core/fxge/dib/cfx_dibitmap_unittest.cpp b/core/fxge/dib/cfx_dibitmap_unittest.cpp
index 2c7de3e..5f45061 100644
--- a/core/fxge/dib/cfx_dibitmap_unittest.cpp
+++ b/core/fxge/dib/cfx_dibitmap_unittest.cpp
@@ -7,10 +7,10 @@
 #include <stdint.h>
 
 #include "core/fxcrt/fx_coordinates.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/dib/fx_dib.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
-#include "third_party/base/containers/span.h"
 
 namespace {
 
diff --git a/core/fxge/dib/cfx_imagestretcher.cpp b/core/fxge/dib/cfx_imagestretcher.cpp
index d6e2b34..7946411 100644
--- a/core/fxge/dib/cfx_imagestretcher.cpp
+++ b/core/fxge/dib/cfx_imagestretcher.cpp
@@ -10,13 +10,13 @@
 
 #include "core/fxcrt/data_vector.h"
 #include "core/fxcrt/fx_safe_types.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/dib/cfx_dibbase.h"
 #include "core/fxge/dib/cfx_dibitmap.h"
 #include "core/fxge/dib/cstretchengine.h"
 #include "core/fxge/dib/fx_dib.h"
 #include "third_party/base/check.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 
 namespace {
 
diff --git a/core/fxge/dib/cfx_scanlinecompositor.h b/core/fxge/dib/cfx_scanlinecompositor.h
index c7e95fd..e540c55 100644
--- a/core/fxge/dib/cfx_scanlinecompositor.h
+++ b/core/fxge/dib/cfx_scanlinecompositor.h
@@ -10,8 +10,8 @@
 #include <memory>
 
 #include "core/fxcrt/fx_memory_wrappers.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/dib/fx_dib.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_ScanlineCompositor {
  public:
diff --git a/core/fxge/dib/cstretchengine.h b/core/fxge/dib/cstretchengine.h
index e443e62..8936cee 100644
--- a/core/fxge/dib/cstretchengine.h
+++ b/core/fxge/dib/cstretchengine.h
@@ -14,10 +14,10 @@
 #include "core/fxcrt/fx_coordinates.h"
 #include "core/fxcrt/fx_system.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "core/fxge/dib/fx_dib.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_DIBBase;
 class PauseIndicatorIface;
diff --git a/core/fxge/dib/scanlinecomposer_iface.h b/core/fxge/dib/scanlinecomposer_iface.h
index e6bbdbe..e9b0b52 100644
--- a/core/fxge/dib/scanlinecomposer_iface.h
+++ b/core/fxge/dib/scanlinecomposer_iface.h
@@ -8,8 +8,8 @@
 #define CORE_FXGE_DIB_SCANLINECOMPOSER_IFACE_H_
 
 #include "core/fxcrt/data_vector.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/dib/fx_dib.h"
-#include "third_party/base/containers/span.h"
 
 class ScanlineComposerIface {
  public:
diff --git a/core/fxge/fx_font.h b/core/fxge/fx_font.h
index 2644e62..d2ef744 100644
--- a/core/fxge/fx_font.h
+++ b/core/fxge/fx_font.h
@@ -13,7 +13,7 @@
 
 #include "core/fxcrt/bytestring.h"
 #include "core/fxcrt/fx_coordinates.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 /* Font pitch and family flags */
 #define FXFONT_FF_FIXEDPITCH (1 << 0)
diff --git a/core/fxge/renderdevicedriver_iface.h b/core/fxge/renderdevicedriver_iface.h
index 6fef089..d391a23 100644
--- a/core/fxge/renderdevicedriver_iface.h
+++ b/core/fxge/renderdevicedriver_iface.h
@@ -13,8 +13,8 @@
 
 #include "core/fxcrt/fx_coordinates.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/dib/fx_dib.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_DIBBase;
 class CFX_DIBitmap;
diff --git a/core/fxge/skia/cfx_dibbase_skia.cpp b/core/fxge/skia/cfx_dibbase_skia.cpp
index 8606e33..27112df 100644
--- a/core/fxge/skia/cfx_dibbase_skia.cpp
+++ b/core/fxge/skia/cfx_dibbase_skia.cpp
@@ -16,11 +16,11 @@
 #include "core/fxcrt/fx_memory_wrappers.h"
 #include "core/fxcrt/fx_safe_types.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/calculate_pitch.h"
 #include "core/fxge/dib/cfx_dibitmap.h"
 #include "core/fxge/dib/fx_dib.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/notreached.h"
 #include "third_party/skia/include/core/SkAlphaType.h"
 #include "third_party/skia/include/core/SkColor.h"
diff --git a/core/fxge/skia/fx_skia_device.cpp b/core/fxge/skia/fx_skia_device.cpp
index 3ccd202..a126b03 100644
--- a/core/fxge/skia/fx_skia_device.cpp
+++ b/core/fxge/skia/fx_skia_device.cpp
@@ -31,6 +31,7 @@
 #include "core/fxcrt/fx_coordinates.h"
 #include "core/fxcrt/fx_memory.h"
 #include "core/fxcrt/fx_system.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/stl_util.h"
 #include "core/fxge/cfx_defaultrenderdevice.h"
 #include "core/fxge/cfx_fillrenderoptions.h"
@@ -47,7 +48,6 @@
 #include "core/fxge/text_char_pos.h"
 #include "third_party/base/check.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/memory/ptr_util.h"
 #include "third_party/base/notreached.h"
 #include "third_party/base/numerics/safe_conversions.h"
diff --git a/core/fxge/skia/fx_skia_device.h b/core/fxge/skia/fx_skia_device.h
index af98e5b..fc21e69 100644
--- a/core/fxge/skia/fx_skia_device.h
+++ b/core/fxge/skia/fx_skia_device.h
@@ -12,12 +12,12 @@
 #include "core/fxcrt/data_vector.h"
 #include "core/fxcrt/fx_memory_wrappers.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "core/fxge/cfx_fillrenderoptions.h"
 #include "core/fxge/cfx_path.h"
 #include "core/fxge/renderdevicedriver_iface.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/skia/include/core/SkPoint.h"
 #include "third_party/skia/include/core/SkRSXform.h"
 #include "third_party/skia/include/core/SkRefCnt.h"
diff --git a/core/fxge/systemfontinfo_iface.h b/core/fxge/systemfontinfo_iface.h
index 90cdb19..985068b 100644
--- a/core/fxge/systemfontinfo_iface.h
+++ b/core/fxge/systemfontinfo_iface.h
@@ -12,8 +12,8 @@
 
 #include "core/fxcrt/bytestring.h"
 #include "core/fxcrt/fx_codepage_forward.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/cfx_fontmapper.h"
-#include "third_party/base/containers/span.h"
 
 constexpr uint32_t kTableNAME = CFX_FontMapper::MakeTag('n', 'a', 'm', 'e');
 constexpr uint32_t kTableTTCF = CFX_FontMapper::MakeTag('t', 't', 'c', 'f');
diff --git a/core/fxge/win32/cfx_psrenderer.h b/core/fxge/win32/cfx_psrenderer.h
index de978f2..7cecfda 100644
--- a/core/fxge/win32/cfx_psrenderer.h
+++ b/core/fxge/win32/cfx_psrenderer.h
@@ -22,9 +22,9 @@
 #include "core/fxcrt/fx_stream.h"
 #include "core/fxcrt/fx_string_wrappers.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "core/fxge/cfx_graphstatedata.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_DIBBase;
 class CFX_Font;
diff --git a/core/fxge/win32/cfx_psrenderer_unittest.cpp b/core/fxge/win32/cfx_psrenderer_unittest.cpp
index 44674e7..38d8e72 100644
--- a/core/fxge/win32/cfx_psrenderer_unittest.cpp
+++ b/core/fxge/win32/cfx_psrenderer_unittest.cpp
@@ -12,11 +12,11 @@
 #include "core/fxcrt/fx_coordinates.h"
 #include "core/fxcrt/fx_stream.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/dib/cfx_dibitmap.h"
 #include "core/fxge/dib/fx_dib.h"
 #include "core/fxge/win32/cfx_psfonttracker.h"
 #include "testing/gtest/include/gtest/gtest.h"
-#include "third_party/base/containers/span.h"
 
 namespace {
 
diff --git a/core/fxge/win32/cgdi_plus_ext.cpp b/core/fxge/win32/cgdi_plus_ext.cpp
index e8bc88d..b86a4b9 100644
--- a/core/fxge/win32/cgdi_plus_ext.cpp
+++ b/core/fxge/win32/cgdi_plus_ext.cpp
@@ -19,6 +19,7 @@
 #include "core/fxcrt/fx_string.h"
 #include "core/fxcrt/fx_string_wrappers.h"
 #include "core/fxcrt/fx_system.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/cfx_fillrenderoptions.h"
 #include "core/fxge/cfx_gemodule.h"
 #include "core/fxge/cfx_graphstatedata.h"
@@ -26,7 +27,6 @@
 #include "core/fxge/dib/cfx_dibbase.h"
 #include "core/fxge/dib/cfx_dibitmap.h"
 #include "core/fxge/win32/cwin32_platform.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/notreached.h"
 #include "third_party/base/numerics/safe_conversions.h"
 
diff --git a/core/fxge/win32/cgdi_plus_ext.h b/core/fxge/win32/cgdi_plus_ext.h
index f5fafaf..bb8fd8e 100644
--- a/core/fxge/win32/cgdi_plus_ext.h
+++ b/core/fxge/win32/cgdi_plus_ext.h
@@ -13,7 +13,7 @@
 #include <vector>
 
 #include "core/fxcrt/retain_ptr.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CFX_DIBBase;
 class CFX_GraphStateData;
diff --git a/core/fxge/win32/cpsoutput.cpp b/core/fxge/win32/cpsoutput.cpp
index 0b391ee..e51151d 100644
--- a/core/fxge/win32/cpsoutput.cpp
+++ b/core/fxge/win32/cpsoutput.cpp
@@ -9,7 +9,7 @@
 #include <algorithm>
 
 #include "core/fxcrt/fx_system.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 CPSOutput::CPSOutput(HDC hDC, OutputMode mode) : m_hDC(hDC), m_mode(mode) {}
 
diff --git a/core/fxge/win32/cwin32_platform.cpp b/core/fxge/win32/cwin32_platform.cpp
index 885cac4..d949b39 100644
--- a/core/fxge/win32/cwin32_platform.cpp
+++ b/core/fxge/win32/cwin32_platform.cpp
@@ -13,10 +13,10 @@
 #include "core/fxcrt/byteorder.h"
 #include "core/fxcrt/fx_codepage.h"
 #include "core/fxcrt/fx_system.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/cfx_folderfontinfo.h"
 #include "core/fxge/cfx_gemodule.h"
 #include "third_party/base/check.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/numerics/safe_conversions.h"
 #include "third_party/base/win/scoped_select_object.h"
 #include "third_party/base/win/win_util.h"
diff --git a/fpdfsdk/cpdfsdk_annotiterator.cpp b/fpdfsdk/cpdfsdk_annotiterator.cpp
index 326624b..cf13574 100644
--- a/fpdfsdk/cpdfsdk_annotiterator.cpp
+++ b/fpdfsdk/cpdfsdk_annotiterator.cpp
@@ -10,13 +10,13 @@
 
 #include "core/fpdfapi/page/cpdf_page.h"
 #include "core/fpdfapi/parser/cpdf_dictionary.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/stl_util.h"
 #include "fpdfsdk/cpdfsdk_annot.h"
 #include "fpdfsdk/cpdfsdk_pageview.h"
 #include "fpdfsdk/cpdfsdk_widget.h"
 #include "third_party/base/containers/adapters.h"
 #include "third_party/base/containers/contains.h"
-#include "third_party/base/containers/span.h"
 
 namespace {
 
diff --git a/fpdfsdk/cpdfsdk_annotiterator.h b/fpdfsdk/cpdfsdk_annotiterator.h
index e1b2e13..a82fcaa 100644
--- a/fpdfsdk/cpdfsdk_annotiterator.h
+++ b/fpdfsdk/cpdfsdk_annotiterator.h
@@ -11,8 +11,8 @@
 
 #include "core/fpdfdoc/cpdf_annot.h"
 #include "core/fxcrt/fx_coordinates.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
-#include "third_party/base/containers/span.h"
 
 class CPDFSDK_Annot;
 class CPDFSDK_PageView;
diff --git a/fpdfsdk/cpdfsdk_appstream.cpp b/fpdfsdk/cpdfsdk_appstream.cpp
index c9d7758..5d582ee 100644
--- a/fpdfsdk/cpdfsdk_appstream.cpp
+++ b/fpdfsdk/cpdfsdk_appstream.cpp
@@ -31,6 +31,7 @@
 #include "core/fpdfdoc/cpdf_icon.h"
 #include "core/fpdfdoc/cpvt_word.h"
 #include "core/fxcrt/fx_string_wrappers.h"
+#include "core/fxcrt/span.h"
 #include "fpdfsdk/cpdfsdk_formfillenvironment.h"
 #include "fpdfsdk/cpdfsdk_interactiveform.h"
 #include "fpdfsdk/cpdfsdk_pageview.h"
@@ -38,7 +39,6 @@
 #include "fpdfsdk/pwl/cpwl_edit.h"
 #include "fpdfsdk/pwl/cpwl_edit_impl.h"
 #include "fpdfsdk/pwl/cpwl_wnd.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/numerics/safe_conversions.h"
 
 namespace {
diff --git a/fpdfsdk/cpdfsdk_formfillenvironment.h b/fpdfsdk/cpdfsdk_formfillenvironment.h
index 3be1962..9005431 100644
--- a/fpdfsdk/cpdfsdk_formfillenvironment.h
+++ b/fpdfsdk/cpdfsdk_formfillenvironment.h
@@ -22,13 +22,13 @@
 #include "core/fxcrt/mask.h"
 #include "core/fxcrt/observed_ptr.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "fpdfsdk/cpdfsdk_annot.h"
 #include "fpdfsdk/formfiller/cffl_interactiveformfiller.h"
 #include "fpdfsdk/pwl/cpwl_wnd.h"
 #include "fpdfsdk/pwl/ipwl_fillernotify.h"
 #include "public/fpdf_formfill.h"
-#include "third_party/base/containers/span.h"
 
 class CPDF_Action;
 class CPDF_FormField;
diff --git a/fpdfsdk/fpdf_annot_embeddertest.cpp b/fpdfsdk/fpdf_annot_embeddertest.cpp
index bc66814..c927375 100644
--- a/fpdfsdk/fpdf_annot_embeddertest.cpp
+++ b/fpdfsdk/fpdf_annot_embeddertest.cpp
@@ -16,6 +16,7 @@
 #include "core/fpdfapi/parser/cpdf_array.h"
 #include "core/fpdfapi/parser/cpdf_dictionary.h"
 #include "core/fxcrt/fx_system.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/cfx_defaultrenderdevice.h"
 #include "fpdfsdk/cpdfsdk_helpers.h"
 #include "public/cpp/fpdf_scopers.h"
@@ -29,7 +30,6 @@
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/utils/hash.h"
 #include "third_party/base/containers/contains.h"
-#include "third_party/base/containers/span.h"
 
 using pdfium::AnnotationStampWithApChecksum;
 
diff --git a/fpdfsdk/fpdf_editpage.cpp b/fpdfsdk/fpdf_editpage.cpp
index c79fc0c..3a2d002 100644
--- a/fpdfsdk/fpdf_editpage.cpp
+++ b/fpdfsdk/fpdf_editpage.cpp
@@ -35,10 +35,10 @@
 #include "core/fpdfdoc/cpdf_annotlist.h"
 #include "core/fxcrt/fx_extension.h"
 #include "core/fxcrt/fx_memcpy_wrappers.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/stl_util.h"
 #include "fpdfsdk/cpdfsdk_helpers.h"
 #include "public/fpdf_formfill.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/numerics/safe_conversions.h"
 
 #ifdef PDF_ENABLE_XFA
diff --git a/fpdfsdk/fpdf_editpath.cpp b/fpdfsdk/fpdf_editpath.cpp
index 4c07d1c..f09744d 100644
--- a/fpdfsdk/fpdf_editpath.cpp
+++ b/fpdfsdk/fpdf_editpath.cpp
@@ -10,9 +10,9 @@
 #include "core/fpdfapi/page/cpdf_path.h"
 #include "core/fpdfapi/page/cpdf_pathobject.h"
 #include "core/fxcrt/fx_system.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/stl_util.h"
 #include "fpdfsdk/cpdfsdk_helpers.h"
-#include "third_party/base/containers/span.h"
 
 // These checks are here because core/ and public/ cannot depend on each other.
 static_assert(static_cast<int>(CFX_GraphStateData::LineCap::kButt) ==
diff --git a/fpdfsdk/fpdf_ppo.cpp b/fpdfsdk/fpdf_ppo.cpp
index e45b036..f3185a1 100644
--- a/fpdfsdk/fpdf_ppo.cpp
+++ b/fpdfsdk/fpdf_ppo.cpp
@@ -34,11 +34,11 @@
 #include "core/fxcrt/fx_safe_types.h"
 #include "core/fxcrt/fx_string_wrappers.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "fpdfsdk/cpdfsdk_helpers.h"
 #include "public/cpp/fpdf_scopers.h"
 #include "third_party/base/check.h"
-#include "third_party/base/containers/span.h"
 
 struct XObjectContext {
   UnownedPtr<CPDF_Document> dest_doc;
diff --git a/fpdfsdk/fpdf_transformpage.cpp b/fpdfsdk/fpdf_transformpage.cpp
index 8eb1d69..3e74761 100644
--- a/fpdfsdk/fpdf_transformpage.cpp
+++ b/fpdfsdk/fpdf_transformpage.cpp
@@ -22,11 +22,11 @@
 #include "core/fpdfapi/parser/cpdf_reference.h"
 #include "core/fpdfapi/parser/cpdf_stream.h"
 #include "core/fxcrt/fx_string_wrappers.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/stl_util.h"
 #include "core/fxge/cfx_fillrenderoptions.h"
 #include "core/fxge/cfx_path.h"
 #include "fpdfsdk/cpdfsdk_helpers.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/numerics/safe_conversions.h"
 
 namespace {
diff --git a/fpdfsdk/fpdf_view.cpp b/fpdfsdk/fpdf_view.cpp
index 3cba971..accacd5 100644
--- a/fpdfsdk/fpdf_view.cpp
+++ b/fpdfsdk/fpdf_view.cpp
@@ -35,6 +35,7 @@
 #include "core/fxcrt/fx_safe_types.h"
 #include "core/fxcrt/fx_stream.h"
 #include "core/fxcrt/fx_system.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/span_util.h"
 #include "core/fxcrt/stl_util.h"
 #include "core/fxcrt/unowned_ptr.h"
@@ -51,7 +52,6 @@
 #include "fxjs/ijs_runtime.h"
 #include "public/fpdf_formfill.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/memory/ptr_util.h"
 #include "third_party/base/numerics/safe_conversions.h"
 
diff --git a/fxbarcode/BC_TwoDimWriter.h b/fxbarcode/BC_TwoDimWriter.h
index cab1f45..ee479e5 100644
--- a/fxbarcode/BC_TwoDimWriter.h
+++ b/fxbarcode/BC_TwoDimWriter.h
@@ -10,8 +10,8 @@
 #include <memory>
 
 #include "core/fxcrt/fx_coordinates.h"
+#include "core/fxcrt/span.h"
 #include "fxbarcode/BC_Writer.h"
-#include "third_party/base/containers/span.h"
 
 class CBC_CommonBitMatrix;
 class CFX_RenderDevice;
diff --git a/fxbarcode/common/BC_CommonByteMatrix.h b/fxbarcode/common/BC_CommonByteMatrix.h
index fa97f69..54fb251 100644
--- a/fxbarcode/common/BC_CommonByteMatrix.h
+++ b/fxbarcode/common/BC_CommonByteMatrix.h
@@ -10,7 +10,7 @@
 #include <stdint.h>
 
 #include "core/fxcrt/data_vector.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CBC_CommonByteMatrix final {
  public:
diff --git a/fxbarcode/oned/BC_OneDimWriter.h b/fxbarcode/oned/BC_OneDimWriter.h
index 3abcce4..085f27a 100644
--- a/fxbarcode/oned/BC_OneDimWriter.h
+++ b/fxbarcode/oned/BC_OneDimWriter.h
@@ -14,11 +14,11 @@
 
 #include "core/fxcrt/data_vector.h"
 #include "core/fxcrt/fx_string.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "core/fxge/cfx_textrenderoptions.h"
 #include "fxbarcode/BC_Library.h"
 #include "fxbarcode/BC_Writer.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_Font;
 class CFX_Matrix;
diff --git a/fxbarcode/pdf417/BC_PDF417BarcodeRow.h b/fxbarcode/pdf417/BC_PDF417BarcodeRow.h
index e67cc43..6ed16e2 100644
--- a/fxbarcode/pdf417/BC_PDF417BarcodeRow.h
+++ b/fxbarcode/pdf417/BC_PDF417BarcodeRow.h
@@ -10,7 +10,7 @@
 #include <stdint.h>
 
 #include "core/fxcrt/fixed_size_data_vector.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CBC_BarcodeRow final {
  public:
diff --git a/fxbarcode/pdf417/BC_PDF417HighLevelEncoder.h b/fxbarcode/pdf417/BC_PDF417HighLevelEncoder.h
index d13968c..f58ff89 100644
--- a/fxbarcode/pdf417/BC_PDF417HighLevelEncoder.h
+++ b/fxbarcode/pdf417/BC_PDF417HighLevelEncoder.h
@@ -9,9 +9,9 @@
 
 #include <optional>
 
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/widestring.h"
 #include "fxbarcode/pdf417/BC_PDF417.h"
-#include "third_party/base/containers/span.h"
 
 class CBC_PDF417HighLevelEncoder {
  public:
diff --git a/fxbarcode/qrcode/BC_QRCoderBitVector.h b/fxbarcode/qrcode/BC_QRCoderBitVector.h
index 51bbe7c..13b77ee 100644
--- a/fxbarcode/qrcode/BC_QRCoderBitVector.h
+++ b/fxbarcode/qrcode/BC_QRCoderBitVector.h
@@ -11,7 +11,7 @@
 #include <stdint.h>
 
 #include "core/fxcrt/data_vector.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class CBC_QRCoderBitVector {
  public:
diff --git a/fxjs/cfx_globaldata.h b/fxjs/cfx_globaldata.h
index 7ca4fd6..5e05500 100644
--- a/fxjs/cfx_globaldata.h
+++ b/fxjs/cfx_globaldata.h
@@ -12,9 +12,9 @@
 #include <vector>
 
 #include "core/fxcrt/binary_buffer.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "fxjs/cfx_keyvalue.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_GlobalData {
  public:
diff --git a/fxjs/cjs_app.cpp b/fxjs/cjs_app.cpp
index 1af0041..29aabe2 100644
--- a/fxjs/cjs_app.cpp
+++ b/fxjs/cjs_app.cpp
@@ -12,6 +12,7 @@
 #include <utility>
 
 #include "core/fxcrt/fixed_size_data_vector.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/stl_util.h"
 #include "fpdfsdk/cpdfsdk_formfillenvironment.h"
 #include "fpdfsdk/cpdfsdk_interactiveform.h"
@@ -20,7 +21,6 @@
 #include "fxjs/global_timer.h"
 #include "fxjs/ijs_event_context.h"
 #include "fxjs/js_resources.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-container.h"
 
 namespace {
diff --git a/fxjs/cjs_app.h b/fxjs/cjs_app.h
index e151258..7fbb776 100644
--- a/fxjs/cjs_app.h
+++ b/fxjs/cjs_app.h
@@ -11,9 +11,9 @@
 #include <set>
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/cjs_object.h"
 #include "fxjs/js_define.h"
-#include "third_party/base/containers/span.h"
 
 class CJS_Runtime;
 class GlobalTimer;
diff --git a/fxjs/cjs_color.cpp b/fxjs/cjs_color.cpp
index 3e3c0aa..c4f47e7 100644
--- a/fxjs/cjs_color.cpp
+++ b/fxjs/cjs_color.cpp
@@ -9,13 +9,13 @@
 #include <algorithm>
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "core/fxge/cfx_color.h"
 #include "fxjs/cjs_event_context.h"
 #include "fxjs/cjs_object.h"
 #include "fxjs/cjs_runtime.h"
 #include "fxjs/fxv8.h"
 #include "fxjs/js_define.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-container.h"
 
 const JSPropertySpec CJS_Color::PropertySpecs[] = {
diff --git a/fxjs/cjs_color.h b/fxjs/cjs_color.h
index 751acd2..0655608 100644
--- a/fxjs/cjs_color.h
+++ b/fxjs/cjs_color.h
@@ -9,10 +9,10 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "core/fxge/cfx_color.h"
 #include "fxjs/cjs_object.h"
 #include "fxjs/js_define.h"
-#include "third_party/base/containers/span.h"
 
 class CJS_Color final : public CJS_Object {
  public:
diff --git a/fxjs/cjs_console.cpp b/fxjs/cjs_console.cpp
index 883c1d4..61eca47 100644
--- a/fxjs/cjs_console.cpp
+++ b/fxjs/cjs_console.cpp
@@ -8,10 +8,10 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/cjs_event_context.h"
 #include "fxjs/cjs_object.h"
 #include "fxjs/js_define.h"
-#include "third_party/base/containers/span.h"
 
 const JSMethodSpec CJS_Console::MethodSpecs[] = {{"clear", clear_static},
                                                  {"hide", hide_static},
diff --git a/fxjs/cjs_console.h b/fxjs/cjs_console.h
index e99637f..65b0fc1 100644
--- a/fxjs/cjs_console.h
+++ b/fxjs/cjs_console.h
@@ -9,9 +9,9 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/cjs_object.h"
 #include "fxjs/js_define.h"
-#include "third_party/base/containers/span.h"
 
 class CJS_Console final : public CJS_Object {
  public:
diff --git a/fxjs/cjs_document.cpp b/fxjs/cjs_document.cpp
index 4336ce2..93591b0 100644
--- a/fxjs/cjs_document.cpp
+++ b/fxjs/cjs_document.cpp
@@ -20,6 +20,7 @@
 #include "core/fpdfapi/parser/cpdf_string.h"
 #include "core/fpdfdoc/cpdf_interactiveform.h"
 #include "core/fpdfdoc/cpdf_nametree.h"
+#include "core/fxcrt/span.h"
 #include "fpdfsdk/cpdfsdk_annotiteration.h"
 #include "fpdfsdk/cpdfsdk_formfillenvironment.h"
 #include "fpdfsdk/cpdfsdk_interactiveform.h"
@@ -32,7 +33,6 @@
 #include "fxjs/cjs_icon.h"
 #include "fxjs/js_resources.h"
 #include "third_party/base/check.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-container.h"
 
 const JSPropertySpec CJS_Document::PropertySpecs[] = {
diff --git a/fxjs/cjs_document.h b/fxjs/cjs_document.h
index 4ec8e44..54fc936 100644
--- a/fxjs/cjs_document.h
+++ b/fxjs/cjs_document.h
@@ -12,9 +12,9 @@
 #include <vector>
 
 #include "core/fxcrt/observed_ptr.h"
+#include "core/fxcrt/span.h"
 #include "fxjs/cjs_object.h"
 #include "fxjs/js_define.h"
-#include "third_party/base/containers/span.h"
 
 class CPDFSDK_InteractiveForm;
 class CPDF_InteractiveForm;
diff --git a/fxjs/cjs_field.cpp b/fxjs/cjs_field.cpp
index 08d9b9d..e1b87da 100644
--- a/fxjs/cjs_field.cpp
+++ b/fxjs/cjs_field.cpp
@@ -18,6 +18,7 @@
 #include "core/fpdfdoc/cpdf_formcontrol.h"
 #include "core/fpdfdoc/cpdf_formfield.h"
 #include "core/fpdfdoc/cpdf_interactiveform.h"
+#include "core/fxcrt/span.h"
 #include "fpdfsdk/cpdfsdk_formfillenvironment.h"
 #include "fpdfsdk/cpdfsdk_interactiveform.h"
 #include "fpdfsdk/cpdfsdk_pageview.h"
@@ -29,7 +30,6 @@
 #include "fxjs/fxv8.h"
 #include "fxjs/js_resources.h"
 #include "third_party/base/check.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/notreached.h"
 #include "v8/include/v8-container.h"
 
diff --git a/fxjs/cjs_field.h b/fxjs/cjs_field.h
index 8d3b737..44ced75 100644
--- a/fxjs/cjs_field.h
+++ b/fxjs/cjs_field.h
@@ -9,10 +9,10 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/cjs_document.h"
 #include "fxjs/cjs_object.h"
 #include "fxjs/js_define.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_FloatRect;
 class CPDF_FormControl;
diff --git a/fxjs/cjs_global.cpp b/fxjs/cjs_global.cpp
index 66963b1..a9dce0c 100644
--- a/fxjs/cjs_global.cpp
+++ b/fxjs/cjs_global.cpp
@@ -11,6 +11,7 @@
 #include <vector>
 
 #include "core/fxcrt/fx_extension.h"
+#include "core/fxcrt/span.h"
 #include "fxjs/cfx_globaldata.h"
 #include "fxjs/cfx_keyvalue.h"
 #include "fxjs/cjs_event_context.h"
@@ -20,7 +21,6 @@
 #include "fxjs/js_resources.h"
 #include "third_party/base/check.h"
 #include "third_party/base/containers/contains.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-isolate.h"
 
 namespace {
diff --git a/fxjs/cjs_global.h b/fxjs/cjs_global.h
index c26814a..c8c0907 100644
--- a/fxjs/cjs_global.h
+++ b/fxjs/cjs_global.h
@@ -11,11 +11,11 @@
 #include <memory>
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "fxjs/cfx_keyvalue.h"
 #include "fxjs/cjs_object.h"
 #include "fxjs/cjs_result.h"
-#include "third_party/base/containers/span.h"
 
 class CFX_GlobalData;
 
diff --git a/fxjs/cjs_object.h b/fxjs/cjs_object.h
index 4c567f2..d63fada 100644
--- a/fxjs/cjs_object.h
+++ b/fxjs/cjs_object.h
@@ -7,9 +7,9 @@
 #ifndef FXJS_CJS_OBJECT_H_
 #define FXJS_CJS_OBJECT_H_
 
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "fxjs/cjs_runtime.h"
-#include "third_party/base/containers/span.h"
 
 class CFXJS_Engine;
 
diff --git a/fxjs/cjs_publicmethods.cpp b/fxjs/cjs_publicmethods.cpp
index 2cd257d..fb8c8af 100644
--- a/fxjs/cjs_publicmethods.cpp
+++ b/fxjs/cjs_publicmethods.cpp
@@ -24,6 +24,7 @@
 #include "core/fpdfdoc/cpdf_interactiveform.h"
 #include "core/fxcrt/fx_extension.h"
 #include "core/fxcrt/fx_string_wrappers.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/cfx_color.h"
 #include "fpdfsdk/cpdfsdk_formfillenvironment.h"
 #include "fpdfsdk/cpdfsdk_interactiveform.h"
@@ -37,7 +38,6 @@
 #include "fxjs/js_define.h"
 #include "fxjs/js_resources.h"
 #include "third_party/base/check.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/numerics/safe_conversions.h"
 #include "v8/include/v8-container.h"
 
diff --git a/fxjs/cjs_publicmethods.h b/fxjs/cjs_publicmethods.h
index 3117d76..e999db6 100644
--- a/fxjs/cjs_publicmethods.h
+++ b/fxjs/cjs_publicmethods.h
@@ -9,9 +9,9 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/cjs_object.h"
 #include "fxjs/cjs_result.h"
-#include "third_party/base/containers/span.h"
 
 class CJS_PublicMethods final : public CJS_Object {
  public:
diff --git a/fxjs/cjs_util.cpp b/fxjs/cjs_util.cpp
index e868fcc..9956917 100644
--- a/fxjs/cjs_util.cpp
+++ b/fxjs/cjs_util.cpp
@@ -15,6 +15,7 @@
 
 #include "build/build_config.h"
 #include "core/fxcrt/fx_extension.h"
+#include "core/fxcrt/span.h"
 #include "fxjs/cjs_event_context.h"
 #include "fxjs/cjs_object.h"
 #include "fxjs/cjs_publicmethods.h"
@@ -24,7 +25,6 @@
 #include "fxjs/js_define.h"
 #include "fxjs/js_resources.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-date.h"
 
 #if BUILDFLAG(IS_ANDROID)
diff --git a/fxjs/cjs_util.h b/fxjs/cjs_util.h
index 6157172..30121e2 100644
--- a/fxjs/cjs_util.h
+++ b/fxjs/cjs_util.h
@@ -9,10 +9,10 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/widestring.h"
 #include "fxjs/cjs_object.h"
 #include "fxjs/js_define.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-forward.h"
 
 class CJS_Util final : public CJS_Object {
diff --git a/fxjs/fxv8.h b/fxjs/fxv8.h
index 62c9bb3..90b8326 100644
--- a/fxjs/fxv8.h
+++ b/fxjs/fxv8.h
@@ -12,7 +12,7 @@
 #include <vector>
 
 #include "core/fxcrt/fx_string.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 #include "v8/include/v8-forward.h"
 
 // The fxv8 functions soften up the interface to the V8 API. In particular,
diff --git a/fxjs/js_define.cpp b/fxjs/js_define.cpp
index 2e2087a..f072fc6 100644
--- a/fxjs/js_define.cpp
+++ b/fxjs/js_define.cpp
@@ -14,12 +14,12 @@
 #include <vector>
 
 #include "core/fxcrt/fx_extension.h"
+#include "core/fxcrt/span.h"
 #include "fxjs/cjs_document.h"
 #include "fxjs/cjs_object.h"
 #include "fxjs/fx_date_helpers.h"
 #include "fxjs/fxv8.h"
 #include "third_party/base/check.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-context.h"
 #include "v8/include/v8-function.h"
 #include "v8/include/v8-isolate.h"
diff --git a/fxjs/js_define.h b/fxjs/js_define.h
index 045cce1..f000bfa 100644
--- a/fxjs/js_define.h
+++ b/fxjs/js_define.h
@@ -9,12 +9,12 @@
 
 #include <memory>
 
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "fxjs/cfxjs_engine.h"
 #include "fxjs/cjs_result.h"
 #include "fxjs/cjs_runtime.h"
 #include "fxjs/js_resources.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-local-handle.h"
 
 class CJS_Object;
diff --git a/fxjs/xfa/cjx_container.cpp b/fxjs/xfa/cjx_container.cpp
index 8e8fb3e..7ba072c 100644
--- a/fxjs/xfa/cjx_container.cpp
+++ b/fxjs/xfa/cjx_container.cpp
@@ -8,10 +8,10 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/xfa/cfxjse_class.h"
 #include "fxjs/xfa/cfxjse_engine.h"
 #include "fxjs/xfa/cfxjse_value.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/cppgc/allocation.h"
 #include "v8/include/v8-object.h"
 #include "xfa/fxfa/parser/cxfa_arraynodelist.h"
diff --git a/fxjs/xfa/cjx_datawindow.cpp b/fxjs/xfa/cjx_datawindow.cpp
index cc6de50..26ec17c 100644
--- a/fxjs/xfa/cjx_datawindow.cpp
+++ b/fxjs/xfa/cjx_datawindow.cpp
@@ -8,8 +8,8 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/xfa/cfxjse_value.h"
-#include "third_party/base/containers/span.h"
 #include "xfa/fxfa/parser/cscript_datawindow.h"
 
 const CJX_MethodSpec CJX_DataWindow::MethodSpecs[] = {
diff --git a/fxjs/xfa/cjx_delta.cpp b/fxjs/xfa/cjx_delta.cpp
index fb535e9..a0fc2ea 100644
--- a/fxjs/xfa/cjx_delta.cpp
+++ b/fxjs/xfa/cjx_delta.cpp
@@ -8,9 +8,9 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/js_resources.h"
 #include "fxjs/xfa/cfxjse_value.h"
-#include "third_party/base/containers/span.h"
 #include "xfa/fxfa/parser/cxfa_delta.h"
 
 const CJX_MethodSpec CJX_Delta::MethodSpecs[] = {{"restore", restore_static}};
diff --git a/fxjs/xfa/cjx_desc.cpp b/fxjs/xfa/cjx_desc.cpp
index 173b810..9b35ac3 100644
--- a/fxjs/xfa/cjx_desc.cpp
+++ b/fxjs/xfa/cjx_desc.cpp
@@ -8,10 +8,10 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/cfx_v8.h"
 #include "fxjs/js_resources.h"
 #include "fxjs/xfa/cfxjse_value.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-primitive.h"
 #include "xfa/fxfa/parser/cxfa_desc.h"
 
diff --git a/fxjs/xfa/cjx_eventpseudomodel.cpp b/fxjs/xfa/cjx_eventpseudomodel.cpp
index dea28e8..1a05db9 100644
--- a/fxjs/xfa/cjx_eventpseudomodel.cpp
+++ b/fxjs/xfa/cjx_eventpseudomodel.cpp
@@ -9,9 +9,9 @@
 #include <algorithm>
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/fxv8.h"
 #include "fxjs/xfa/cfxjse_engine.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/notreached.h"
 #include "third_party/base/numerics/safe_conversions.h"
 #include "v8/include/v8-primitive.h"
diff --git a/fxjs/xfa/cjx_exclgroup.cpp b/fxjs/xfa/cjx_exclgroup.cpp
index 9d5cfef..0e01fac 100644
--- a/fxjs/xfa/cjx_exclgroup.cpp
+++ b/fxjs/xfa/cjx_exclgroup.cpp
@@ -8,10 +8,10 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/fxv8.h"
 #include "fxjs/js_resources.h"
 #include "fxjs/xfa/cfxjse_engine.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-object.h"
 #include "v8/include/v8-primitive.h"
 #include "xfa/fxfa/cxfa_eventparam.h"
diff --git a/fxjs/xfa/cjx_field.cpp b/fxjs/xfa/cjx_field.cpp
index c9e2b51..828df67 100644
--- a/fxjs/xfa/cjx_field.cpp
+++ b/fxjs/xfa/cjx_field.cpp
@@ -8,10 +8,10 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/cfx_v8.h"
 #include "fxjs/fxv8.h"
 #include "fxjs/js_resources.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/numerics/safe_conversions.h"
 #include "v8/include/v8-primitive.h"
 #include "xfa/fgas/crt/cfgas_decimal.h"
diff --git a/fxjs/xfa/cjx_form.cpp b/fxjs/xfa/cjx_form.cpp
index 9513786..13cdb83 100644
--- a/fxjs/xfa/cjx_form.cpp
+++ b/fxjs/xfa/cjx_form.cpp
@@ -8,10 +8,10 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/fxv8.h"
 #include "fxjs/js_resources.h"
 #include "fxjs/xfa/cfxjse_engine.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/cppgc/allocation.h"
 #include "v8/include/v8-object.h"
 #include "v8/include/v8-primitive.h"
diff --git a/fxjs/xfa/cjx_hostpseudomodel.cpp b/fxjs/xfa/cjx_hostpseudomodel.cpp
index 8bdd809..656e997 100644
--- a/fxjs/xfa/cjx_hostpseudomodel.cpp
+++ b/fxjs/xfa/cjx_hostpseudomodel.cpp
@@ -8,11 +8,11 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/fxv8.h"
 #include "fxjs/js_resources.h"
 #include "fxjs/xfa/cfxjse_engine.h"
 #include "third_party/base/check.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-object.h"
 #include "xfa/fxfa/cxfa_ffdoc.h"
 #include "xfa/fxfa/cxfa_ffnotify.h"
diff --git a/fxjs/xfa/cjx_instancemanager.cpp b/fxjs/xfa/cjx_instancemanager.cpp
index 2e3a375..e86a5cd 100644
--- a/fxjs/xfa/cjx_instancemanager.cpp
+++ b/fxjs/xfa/cjx_instancemanager.cpp
@@ -9,11 +9,11 @@
 #include <algorithm>
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/fxv8.h"
 #include "fxjs/js_resources.h"
 #include "fxjs/xfa/cfxjse_engine.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-object.h"
 #include "v8/include/v8-primitive.h"
 #include "xfa/fxfa/cxfa_ffdoc.h"
diff --git a/fxjs/xfa/cjx_layoutpseudomodel.h b/fxjs/xfa/cjx_layoutpseudomodel.h
index 17bbfc3..e86d992 100644
--- a/fxjs/xfa/cjx_layoutpseudomodel.h
+++ b/fxjs/xfa/cjx_layoutpseudomodel.h
@@ -9,9 +9,9 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/xfa/cjx_object.h"
 #include "fxjs/xfa/jse_define.h"
-#include "third_party/base/containers/span.h"
 
 class CScript_LayoutPseudoModel;
 class CXFA_LayoutProcessor;
diff --git a/fxjs/xfa/cjx_list.cpp b/fxjs/xfa/cjx_list.cpp
index 9eccdcd..a016ef2 100644
--- a/fxjs/xfa/cjx_list.cpp
+++ b/fxjs/xfa/cjx_list.cpp
@@ -8,11 +8,11 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/fxv8.h"
 #include "fxjs/js_resources.h"
 #include "fxjs/xfa/cfxjse_class.h"
 #include "fxjs/xfa/cfxjse_engine.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/numerics/safe_conversions.h"
 #include "v8/include/v8-object.h"
 #include "v8/include/v8-primitive.h"
diff --git a/fxjs/xfa/cjx_logpseudomodel.cpp b/fxjs/xfa/cjx_logpseudomodel.cpp
index 01faaad..d2af347 100644
--- a/fxjs/xfa/cjx_logpseudomodel.cpp
+++ b/fxjs/xfa/cjx_logpseudomodel.cpp
@@ -8,8 +8,8 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/xfa/cfxjse_value.h"
-#include "third_party/base/containers/span.h"
 #include "xfa/fxfa/parser/cscript_logpseudomodel.h"
 
 const CJX_MethodSpec CJX_LogPseudoModel::MethodSpecs[] = {
diff --git a/fxjs/xfa/cjx_manifest.cpp b/fxjs/xfa/cjx_manifest.cpp
index 9450187..2a24c20 100644
--- a/fxjs/xfa/cjx_manifest.cpp
+++ b/fxjs/xfa/cjx_manifest.cpp
@@ -8,10 +8,10 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/cfx_v8.h"
 #include "fxjs/js_resources.h"
 #include "fxjs/xfa/cfxjse_value.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-primitive.h"
 #include "xfa/fxfa/parser/cxfa_manifest.h"
 
diff --git a/fxjs/xfa/cjx_model.cpp b/fxjs/xfa/cjx_model.cpp
index 00529e7..b1df28a 100644
--- a/fxjs/xfa/cjx_model.cpp
+++ b/fxjs/xfa/cjx_model.cpp
@@ -8,10 +8,10 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/js_resources.h"
 #include "fxjs/xfa/cfxjse_engine.h"
 #include "fxjs/xfa/cfxjse_value.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-object.h"
 #include "xfa/fxfa/parser/cxfa_delta.h"
 #include "xfa/fxfa/parser/cxfa_document.h"
diff --git a/fxjs/xfa/cjx_node.cpp b/fxjs/xfa/cjx_node.cpp
index bdae56e..bb79069 100644
--- a/fxjs/xfa/cjx_node.cpp
+++ b/fxjs/xfa/cjx_node.cpp
@@ -13,13 +13,13 @@
 #include "core/fxcrt/cfx_memorystream.h"
 #include "core/fxcrt/cfx_read_only_string_stream.h"
 #include "core/fxcrt/fx_codepage.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/xml/cfx_xmldocument.h"
 #include "core/fxcrt/xml/cfx_xmlelement.h"
 #include "core/fxcrt/xml/cfx_xmlparser.h"
 #include "fxjs/fxv8.h"
 #include "fxjs/js_resources.h"
 #include "fxjs/xfa/cfxjse_engine.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-object.h"
 #include "xfa/fxfa/cxfa_eventparam.h"
 #include "xfa/fxfa/cxfa_ffdoc.h"
diff --git a/fxjs/xfa/cjx_object.cpp b/fxjs/xfa/cjx_object.cpp
index f68cdc2..2d14fe6 100644
--- a/fxjs/xfa/cjx_object.cpp
+++ b/fxjs/xfa/cjx_object.cpp
@@ -12,6 +12,7 @@
 
 #include "core/fxcrt/fx_extension.h"
 #include "core/fxcrt/fx_memory.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/xml/cfx_xmlelement.h"
 #include "core/fxcrt/xml/cfx_xmltext.h"
 #include "fxjs/cjs_result.h"
@@ -26,7 +27,6 @@
 #include "third_party/base/check.h"
 #include "third_party/base/check_op.h"
 #include "third_party/base/containers/contains.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-forward.h"
 #include "v8/include/v8-object.h"
 #include "v8/include/v8-primitive.h"
diff --git a/fxjs/xfa/cjx_object.h b/fxjs/xfa/cjx_object.h
index 1736d2a..efd7ed5 100644
--- a/fxjs/xfa/cjx_object.h
+++ b/fxjs/xfa/cjx_object.h
@@ -12,11 +12,11 @@
 #include <optional>
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/widestring.h"
 #include "fxjs/gc/heap.h"
 #include "fxjs/xfa/fxjse.h"
 #include "fxjs/xfa/jse_define.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/cppgc/garbage-collected.h"
 #include "v8/include/cppgc/member.h"
 #include "v8/include/v8-forward.h"
diff --git a/fxjs/xfa/cjx_packet.cpp b/fxjs/xfa/cjx_packet.cpp
index b7d36e8..e4340df 100644
--- a/fxjs/xfa/cjx_packet.cpp
+++ b/fxjs/xfa/cjx_packet.cpp
@@ -9,13 +9,13 @@
 #include <utility>
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/xml/cfx_xmldocument.h"
 #include "core/fxcrt/xml/cfx_xmlelement.h"
 #include "core/fxcrt/xml/cfx_xmltext.h"
 #include "fxjs/cfx_v8.h"
 #include "fxjs/fxv8.h"
 #include "fxjs/js_resources.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-primitive.h"
 #include "xfa/fxfa/cxfa_ffdoc.h"
 #include "xfa/fxfa/cxfa_ffnotify.h"
diff --git a/fxjs/xfa/cjx_signaturepseudomodel.cpp b/fxjs/xfa/cjx_signaturepseudomodel.cpp
index 4734c47..612270a 100644
--- a/fxjs/xfa/cjx_signaturepseudomodel.cpp
+++ b/fxjs/xfa/cjx_signaturepseudomodel.cpp
@@ -8,10 +8,10 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/js_resources.h"
 #include "fxjs/xfa/cfxjse_engine.h"
 #include "fxjs/xfa/cfxjse_value.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-primitive.h"
 #include "xfa/fxfa/parser/cscript_signaturepseudomodel.h"
 
diff --git a/fxjs/xfa/cjx_source.cpp b/fxjs/xfa/cjx_source.cpp
index fd1a6cb..bf8ed37 100644
--- a/fxjs/xfa/cjx_source.cpp
+++ b/fxjs/xfa/cjx_source.cpp
@@ -8,9 +8,9 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/js_resources.h"
 #include "fxjs/xfa/cfxjse_value.h"
-#include "third_party/base/containers/span.h"
 #include "xfa/fxfa/parser/cxfa_source.h"
 
 const CJX_MethodSpec CJX_Source::MethodSpecs[] = {
diff --git a/fxjs/xfa/cjx_subform.cpp b/fxjs/xfa/cjx_subform.cpp
index 4fdad59..5ec4236 100644
--- a/fxjs/xfa/cjx_subform.cpp
+++ b/fxjs/xfa/cjx_subform.cpp
@@ -8,11 +8,11 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/cfx_v8.h"
 #include "fxjs/fxv8.h"
 #include "fxjs/js_resources.h"
 #include "fxjs/xfa/cfxjse_engine.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-object.h"
 #include "xfa/fxfa/cxfa_eventparam.h"
 #include "xfa/fxfa/cxfa_ffnotify.h"
diff --git a/fxjs/xfa/cjx_template.cpp b/fxjs/xfa/cjx_template.cpp
index 321036c..88ecb90 100644
--- a/fxjs/xfa/cjx_template.cpp
+++ b/fxjs/xfa/cjx_template.cpp
@@ -8,10 +8,10 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/cfx_v8.h"
 #include "fxjs/js_resources.h"
 #include "fxjs/xfa/cfxjse_value.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-primitive.h"
 #include "xfa/fxfa/parser/cxfa_document.h"
 #include "xfa/fxfa/parser/cxfa_template.h"
diff --git a/fxjs/xfa/cjx_tree.cpp b/fxjs/xfa/cjx_tree.cpp
index 76b3a3c..09eafce 100644
--- a/fxjs/xfa/cjx_tree.cpp
+++ b/fxjs/xfa/cjx_tree.cpp
@@ -8,11 +8,11 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/fxv8.h"
 #include "fxjs/js_resources.h"
 #include "fxjs/xfa/cfxjse_class.h"
 #include "fxjs/xfa/cfxjse_engine.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/numerics/safe_conversions.h"
 #include "v8/include/cppgc/allocation.h"
 #include "v8/include/v8-object.h"
diff --git a/fxjs/xfa/cjx_treelist.cpp b/fxjs/xfa/cjx_treelist.cpp
index 898804a..b6753d3 100644
--- a/fxjs/xfa/cjx_treelist.cpp
+++ b/fxjs/xfa/cjx_treelist.cpp
@@ -8,10 +8,10 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/js_resources.h"
 #include "fxjs/xfa/cfxjse_engine.h"
 #include "fxjs/xfa/cfxjse_value.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-object.h"
 #include "xfa/fxfa/parser/cxfa_document.h"
 #include "xfa/fxfa/parser/cxfa_node.h"
diff --git a/fxjs/xfa/cjx_wsdlconnection.cpp b/fxjs/xfa/cjx_wsdlconnection.cpp
index c7c1983..e6b32e4 100644
--- a/fxjs/xfa/cjx_wsdlconnection.cpp
+++ b/fxjs/xfa/cjx_wsdlconnection.cpp
@@ -8,10 +8,10 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/cfx_v8.h"
 #include "fxjs/js_resources.h"
 #include "fxjs/xfa/cfxjse_value.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/v8-primitive.h"
 #include "xfa/fxfa/parser/cxfa_wsdlconnection.h"
 
diff --git a/fxjs/xfa/jse_define.h b/fxjs/xfa/jse_define.h
index 7b991b1..f73fad2 100644
--- a/fxjs/xfa/jse_define.h
+++ b/fxjs/xfa/jse_define.h
@@ -9,8 +9,8 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "fxjs/cjs_result.h"
-#include "third_party/base/containers/span.h"
 
 class CFXJSE_Engine;
 
diff --git a/testing/embedder_test.h b/testing/embedder_test.h
index ef0ac8e..97e44eb 100644
--- a/testing/embedder_test.h
+++ b/testing/embedder_test.h
@@ -14,6 +14,7 @@
 #include <vector>
 
 #include "build/build_config.h"
+#include "core/fxcrt/span.h"
 #include "public/cpp/fpdf_scopers.h"
 #include "public/fpdf_dataavail.h"
 #include "public/fpdf_ext.h"
@@ -22,7 +23,6 @@
 #include "public/fpdfview.h"
 #include "testing/fake_file_access.h"
 #include "testing/gtest/include/gtest/gtest.h"
-#include "third_party/base/containers/span.h"
 
 class TestLoader;
 
diff --git a/testing/fuzzers/BUILD.gn b/testing/fuzzers/BUILD.gn
index 6c915cb..6baf1ed 100644
--- a/testing/fuzzers/BUILD.gn
+++ b/testing/fuzzers/BUILD.gn
@@ -170,8 +170,8 @@
   configs += [ ":fuzzer_config" ]
   deps = [
     "../../:pdfium_public_headers",
+    "../../core/fxcrt",
     "../../fpdfsdk",
-    "../../third_party:pdfium_base",
   ]
 }
 
@@ -531,7 +531,7 @@
   sources = [ "pdf_codec_icc_fuzzer.cc" ]
   deps = [
     "../../core/fxcodec",
-    "../../third_party:pdfium_base",
+    "../../core/fxcrt",
     "../../third_party/:lcms2",
   ]
 }
diff --git a/testing/fuzzers/pdf_cmap_fuzzer.cc b/testing/fuzzers/pdf_cmap_fuzzer.cc
index 58dfbe6..030ffd9 100644
--- a/testing/fuzzers/pdf_cmap_fuzzer.cc
+++ b/testing/fuzzers/pdf_cmap_fuzzer.cc
@@ -6,7 +6,7 @@
 
 #include "core/fpdfapi/font/cpdf_cmap.h"
 #include "core/fxcrt/retain_ptr.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   if (size > 256 * 1024)
diff --git a/testing/fuzzers/pdf_codec_icc_fuzzer.cc b/testing/fuzzers/pdf_codec_icc_fuzzer.cc
index ada4bc7..1f74e6a 100644
--- a/testing/fuzzers/pdf_codec_icc_fuzzer.cc
+++ b/testing/fuzzers/pdf_codec_icc_fuzzer.cc
@@ -5,7 +5,7 @@
 #include <cstdint>
 
 #include "core/fxcodec/icc/icc_transform.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   std::unique_ptr<fxcodec::IccTransform> transform =
diff --git a/testing/fuzzers/pdf_hint_table_fuzzer.cc b/testing/fuzzers/pdf_hint_table_fuzzer.cc
index a90199c..f4b918c 100644
--- a/testing/fuzzers/pdf_hint_table_fuzzer.cc
+++ b/testing/fuzzers/pdf_hint_table_fuzzer.cc
@@ -11,7 +11,7 @@
 #include "core/fpdfapi/parser/cpdf_linearized_header.h"
 #include "core/fpdfapi/parser/cpdf_number.h"
 #include "core/fxcrt/cfx_bitstream.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 int32_t GetData(const int32_t** data32, const uint8_t** data, size_t* size) {
   const int32_t* ret = *data32;
diff --git a/testing/fuzzers/pdf_nametree_fuzzer.cc b/testing/fuzzers/pdf_nametree_fuzzer.cc
index 98a6441..fd3a441 100644
--- a/testing/fuzzers/pdf_nametree_fuzzer.cc
+++ b/testing/fuzzers/pdf_nametree_fuzzer.cc
@@ -11,7 +11,7 @@
 #include "core/fpdfapi/parser/cpdf_dictionary.h"
 #include "core/fpdfapi/parser/cpdf_object.h"
 #include "core/fpdfdoc/cpdf_nametree.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 struct Params {
   bool delete_backwards;
diff --git a/testing/fuzzers/pdf_psengine_fuzzer.cc b/testing/fuzzers/pdf_psengine_fuzzer.cc
index f24bdce..d1dbdee 100644
--- a/testing/fuzzers/pdf_psengine_fuzzer.cc
+++ b/testing/fuzzers/pdf_psengine_fuzzer.cc
@@ -5,7 +5,7 @@
 #include <stdint.h>
 
 #include "core/fpdfapi/page/cpdf_psengine.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   CPDF_PSEngine engine;
diff --git a/testing/fuzzers/pdf_streamparser_fuzzer.cc b/testing/fuzzers/pdf_streamparser_fuzzer.cc
index 6921cc9..8d89bed 100644
--- a/testing/fuzzers/pdf_streamparser_fuzzer.cc
+++ b/testing/fuzzers/pdf_streamparser_fuzzer.cc
@@ -6,7 +6,7 @@
 
 #include "core/fpdfapi/page/cpdf_streamparser.h"
 #include "core/fpdfapi/parser/cpdf_object.h"
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   CPDF_StreamParser parser(pdfium::make_span(data, size));
diff --git a/testing/fuzzers/pdf_xml_fuzzer.cc b/testing/fuzzers/pdf_xml_fuzzer.cc
index e908a7e..bf24bce 100644
--- a/testing/fuzzers/pdf_xml_fuzzer.cc
+++ b/testing/fuzzers/pdf_xml_fuzzer.cc
@@ -9,10 +9,10 @@
 #include "core/fxcrt/cfx_read_only_span_stream.h"
 #include "core/fxcrt/fx_safe_types.h"
 #include "core/fxcrt/fx_system.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/xml/cfx_xmldocument.h"
 #include "core/fxcrt/xml/cfx_xmlelement.h"
 #include "core/fxcrt/xml/cfx_xmlparser.h"
-#include "third_party/base/containers/span.h"
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   FX_SAFE_SIZE_T safe_size = size;
diff --git a/testing/fuzzers/pdfium_fuzzer_helper.cc b/testing/fuzzers/pdfium_fuzzer_helper.cc
index 5b4fbc8..efa444f 100644
--- a/testing/fuzzers/pdfium_fuzzer_helper.cc
+++ b/testing/fuzzers/pdfium_fuzzer_helper.cc
@@ -16,12 +16,12 @@
 #include <tuple>
 #include <utility>
 
+#include "core/fxcrt/span.h"
 #include "public/cpp/fpdf_scopers.h"
 #include "public/fpdf_dataavail.h"
 #include "public/fpdf_ext.h"
 #include "public/fpdf_text.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/numerics/checked_math.h"
 
 namespace {
diff --git a/testing/fuzzers/xfa_codec_fuzzer.h b/testing/fuzzers/xfa_codec_fuzzer.h
index aaa884b..f045438 100644
--- a/testing/fuzzers/xfa_codec_fuzzer.h
+++ b/testing/fuzzers/xfa_codec_fuzzer.h
@@ -13,8 +13,8 @@
 #include "core/fxcrt/cfx_read_only_span_stream.h"
 #include "core/fxcrt/fx_safe_types.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxge/dib/cfx_dibitmap.h"
-#include "third_party/base/containers/span.h"
 
 // Support up to 64 MB. This prevents trivial OOM when MSAN is on and
 // time outs.
diff --git a/testing/fx_string_testhelpers.cpp b/testing/fx_string_testhelpers.cpp
index 399335c..29e2b7b 100644
--- a/testing/fx_string_testhelpers.cpp
+++ b/testing/fx_string_testhelpers.cpp
@@ -10,9 +10,9 @@
 
 #include "core/fxcrt/cfx_datetime.h"
 #include "core/fxcrt/fx_string.h"
+#include "core/fxcrt/span.h"
 #include "fpdfsdk/cpdfsdk_helpers.h"
 #include "third_party/base/check_op.h"
-#include "third_party/base/containers/span.h"
 
 std::ostream& operator<<(std::ostream& os, const CFX_DateTime& dt) {
   os << dt.GetYear() << "-" << std::to_string(dt.GetMonth()) << "-"
diff --git a/testing/image_diff/BUILD.gn b/testing/image_diff/BUILD.gn
index 0f9b71b..a311ec9 100644
--- a/testing/image_diff/BUILD.gn
+++ b/testing/image_diff/BUILD.gn
@@ -14,8 +14,8 @@
     "../../:pdfium_strict_config",
     "../../:pdfium_noshorten_config",
   ]
+  public_deps = [ "../../core/fxcrt" ]
   deps = [
-    "../../third_party:pdfium_base",
     "../../third_party:png",
     "../../third_party:zlib",
   ]
diff --git a/testing/image_diff/image_diff_png.h b/testing/image_diff/image_diff_png.h
index 5d54c95..74ecfdf 100644
--- a/testing/image_diff/image_diff_png.h
+++ b/testing/image_diff/image_diff_png.h
@@ -9,7 +9,7 @@
 
 #include <vector>
 
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 namespace image_diff_png {
 
diff --git a/testing/test_loader.h b/testing/test_loader.h
index 77f6be6..680092c 100644
--- a/testing/test_loader.h
+++ b/testing/test_loader.h
@@ -7,7 +7,7 @@
 
 #include <stdint.h>
 
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 class TestLoader {
  public:
diff --git a/testing/utils/hash.h b/testing/utils/hash.h
index e508993..f75af9ba 100644
--- a/testing/utils/hash.h
+++ b/testing/utils/hash.h
@@ -7,7 +7,7 @@
 
 #include <string>
 
-#include "third_party/base/containers/span.h"
+#include "core/fxcrt/span.h"
 
 std::string CryptToBase16(const uint8_t* digest);
 std::string GenerateMD5Base16(pdfium::span<const uint8_t> data);
diff --git a/third_party/BUILD.gn b/third_party/BUILD.gn
index 33d0fa2..ce7e915 100644
--- a/third_party/BUILD.gn
+++ b/third_party/BUILD.gn
@@ -558,7 +558,6 @@
     "base/component_export.h",
     "base/containers/adapters.h",
     "base/containers/contains.h",
-    "base/containers/span.h",
     "base/debug/alias.cc",
     "base/debug/alias.h",
     "base/immediate_crash.h",
@@ -591,9 +590,6 @@
       "base/win/win_util.h",
     ]
   }
-  if (pdf_use_partition_alloc) {
-    public_deps += [ ":pdfium_pa" ]
-  }
 }
 
 source_set("pdfium_base_test_support") {
diff --git a/xfa/fde/cfde_textout.h b/xfa/fde/cfde_textout.h
index af2308b..2f08c59 100644
--- a/xfa/fde/cfde_textout.h
+++ b/xfa/fde/cfde_textout.h
@@ -12,9 +12,9 @@
 #include <vector>
 
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/widestring.h"
 #include "core/fxge/dib/fx_dib.h"
-#include "third_party/base/containers/span.h"
 #include "xfa/fde/cfde_data.h"
 #include "xfa/fgas/layout/cfgas_break.h"
 #include "xfa/fgas/layout/cfgas_char.h"
diff --git a/xfa/fgas/crt/cfgas_stringformatter.h b/xfa/fgas/crt/cfgas_stringformatter.h
index 0acc76d..c7d9b56 100644
--- a/xfa/fgas/crt/cfgas_stringformatter.h
+++ b/xfa/fgas/crt/cfgas_stringformatter.h
@@ -9,8 +9,8 @@
 
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/widestring.h"
-#include "third_party/base/containers/span.h"
 #include "xfa/fgas/crt/locale_iface.h"
 
 class CFX_DateTime;
diff --git a/xfa/fgas/font/cfgas_fontmgr.cpp b/xfa/fgas/font/cfgas_fontmgr.cpp
index cdf8d0d..4c973bd 100644
--- a/xfa/fgas/font/cfgas_fontmgr.cpp
+++ b/xfa/fgas/font/cfgas_fontmgr.cpp
@@ -22,6 +22,7 @@
 #include "core/fxcrt/fx_extension.h"
 #include "core/fxcrt/fx_memory_wrappers.h"
 #include "core/fxcrt/fx_system.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/span_util.h"
 #include "core/fxge/cfx_font.h"
 #include "core/fxge/cfx_fontmapper.h"
@@ -31,7 +32,6 @@
 #include "core/fxge/fx_fontencoding.h"
 #include "third_party/base/check.h"
 #include "third_party/base/containers/contains.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/numerics/safe_conversions.h"
 #include "xfa/fgas/font/cfgas_gefont.h"
 #include "xfa/fgas/font/fgas_fontutils.h"
diff --git a/xfa/fgas/graphics/cfgas_gegraphics.h b/xfa/fgas/graphics/cfgas_gegraphics.h
index 8e4e408..f97bd9f 100644
--- a/xfa/fgas/graphics/cfgas_gegraphics.h
+++ b/xfa/fgas/graphics/cfgas_gegraphics.h
@@ -13,10 +13,10 @@
 #include "core/fxcrt/fx_coordinates.h"
 #include "core/fxcrt/fx_memory.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "core/fxge/cfx_fillrenderoptions.h"
 #include "core/fxge/cfx_graphstatedata.h"
-#include "third_party/base/containers/span.h"
 #include "xfa/fgas/graphics/cfgas_gecolor.h"
 
 class CFGAS_GEPath;
diff --git a/xfa/fxfa/parser/cxfa_document.h b/xfa/fxfa/parser/cxfa_document.h
index 0bccfe0..cb749f5 100644
--- a/xfa/fxfa/parser/cxfa_document.h
+++ b/xfa/fxfa/parser/cxfa_document.h
@@ -15,10 +15,10 @@
 #include <optional>
 #include <vector>
 
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "core/fxcrt/widestring.h"
 #include "fxjs/gc/heap.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/cppgc/garbage-collected.h"
 #include "v8/include/cppgc/member.h"
 #include "v8/include/cppgc/persistent.h"
diff --git a/xfa/fxfa/parser/cxfa_localevalue.cpp b/xfa/fxfa/parser/cxfa_localevalue.cpp
index b3b0970..a0f47d5 100644
--- a/xfa/fxfa/parser/cxfa_localevalue.cpp
+++ b/xfa/fxfa/parser/cxfa_localevalue.cpp
@@ -14,8 +14,8 @@
 
 #include "core/fxcrt/cfx_datetime.h"
 #include "core/fxcrt/fx_extension.h"
+#include "core/fxcrt/span.h"
 #include "third_party/base/check.h"
-#include "third_party/base/containers/span.h"
 #include "xfa/fgas/crt/cfgas_stringformatter.h"
 #include "xfa/fxfa/parser/cxfa_document.h"
 #include "xfa/fxfa/parser/cxfa_localemgr.h"
diff --git a/xfa/fxfa/parser/cxfa_node.cpp b/xfa/fxfa/parser/cxfa_node.cpp
index 1adf44c..8d5bb7e 100644
--- a/xfa/fxfa/parser/cxfa_node.cpp
+++ b/xfa/fxfa/parser/cxfa_node.cpp
@@ -22,6 +22,7 @@
 #include "core/fxcrt/data_vector.h"
 #include "core/fxcrt/fx_codepage.h"
 #include "core/fxcrt/fx_extension.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/stl_util.h"
 #include "core/fxcrt/xml/cfx_xmldocument.h"
 #include "core/fxcrt/xml/cfx_xmlelement.h"
@@ -36,7 +37,6 @@
 #include "third_party/base/check.h"
 #include "third_party/base/check_op.h"
 #include "third_party/base/containers/contains.h"
-#include "third_party/base/containers/span.h"
 #include "third_party/base/notreached.h"
 #include "xfa/fde/cfde_textout.h"
 #include "xfa/fgas/crt/cfgas_decimal.h"
diff --git a/xfa/fxfa/parser/cxfa_node.h b/xfa/fxfa/parser/cxfa_node.h
index 5ed0487..ff996b7 100644
--- a/xfa/fxfa/parser/cxfa_node.h
+++ b/xfa/fxfa/parser/cxfa_node.h
@@ -17,12 +17,12 @@
 #include "core/fxcrt/fx_coordinates.h"
 #include "core/fxcrt/mask.h"
 #include "core/fxcrt/retain_ptr.h"
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "core/fxcrt/unowned_ptr_exclusion.h"
 #include "core/fxcrt/widestring.h"
 #include "core/fxge/dib/fx_dib.h"
 #include "fxjs/gc/gced_tree_node_mixin.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/cppgc/member.h"
 #include "v8/include/cppgc/visitor.h"
 #include "xfa/fxfa/cxfa_ffwidget_type.h"
diff --git a/xfa/fxfa/parser/cxfa_xmllocale.h b/xfa/fxfa/parser/cxfa_xmllocale.h
index 0c045ff..e738f2c 100644
--- a/xfa/fxfa/parser/cxfa_xmllocale.h
+++ b/xfa/fxfa/parser/cxfa_xmllocale.h
@@ -9,9 +9,9 @@
 
 #include <memory>
 
+#include "core/fxcrt/span.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "fxjs/gc/heap.h"
-#include "third_party/base/containers/span.h"
 #include "v8/include/cppgc/garbage-collected.h"
 #include "xfa/fxfa/parser/gced_locale_iface.h"