diff --git a/core/fpdfapi/edit/cpdf_pagecontentmanager.h b/core/fpdfapi/edit/cpdf_pagecontentmanager.h
index b4e03b2..1552957 100644
--- a/core/fpdfapi/edit/cpdf_pagecontentmanager.h
+++ b/core/fpdfapi/edit/cpdf_pagecontentmanager.h
@@ -13,7 +13,6 @@
 
 class CPDF_Array;
 class CPDF_Document;
-class CPDF_Object;
 class CPDF_Stream;
 class CPDF_PageObjectHolder;
 
diff --git a/core/fpdfapi/font/cpdf_cidfont.h b/core/fpdfapi/font/cpdf_cidfont.h
index 5a51e40..11f6d81 100644
--- a/core/fpdfapi/font/cpdf_cidfont.h
+++ b/core/fpdfapi/font/cpdf_cidfont.h
@@ -28,7 +28,6 @@
 };
 
 class CFX_CTTGSUBTable;
-class CPDF_Array;
 class CPDF_CID2UnicodeMap;
 class CPDF_CMap;
 class CPDF_StreamAcc;
diff --git a/core/fpdfapi/font/cpdf_font.h b/core/fpdfapi/font/cpdf_font.h
index 5390b36..a70ffe4 100644
--- a/core/fpdfapi/font/cpdf_font.h
+++ b/core/fpdfapi/font/cpdf_font.h
@@ -25,7 +25,6 @@
 class CFX_SubstFont;
 class CPDF_CIDFont;
 class CPDF_Document;
-class CPDF_Object;
 class CPDF_TrueTypeFont;
 class CPDF_Type1Font;
 class CPDF_Type3Char;
diff --git a/core/fpdfapi/font/cpdf_type3font.h b/core/fpdfapi/font/cpdf_type3font.h
index 40b673c..bcbb704 100644
--- a/core/fpdfapi/font/cpdf_type3font.h
+++ b/core/fpdfapi/font/cpdf_type3font.h
@@ -18,7 +18,6 @@
 
 class CPDF_Dictionary;
 class CPDF_Document;
-class CPDF_Stream;
 class CPDF_Type3Char;
 
 class CPDF_Type3Font final : public CPDF_SimpleFont {
diff --git a/core/fpdfapi/page/cpdf_form.h b/core/fpdfapi/page/cpdf_form.h
index 6f571a2..0731713 100644
--- a/core/fpdfapi/page/cpdf_form.h
+++ b/core/fpdfapi/page/cpdf_form.h
@@ -18,7 +18,6 @@
 class CPDF_AllStates;
 class CPDF_Dictionary;
 class CPDF_Document;
-class CPDF_ImageObject;
 class CPDF_Stream;
 class CPDF_Type3Char;
 
diff --git a/core/fpdfapi/page/cpdf_pageobjectholder.h b/core/fpdfapi/page/cpdf_pageobjectholder.h
index 29ab76d..3eb976e 100644
--- a/core/fpdfapi/page/cpdf_pageobjectholder.h
+++ b/core/fpdfapi/page/cpdf_pageobjectholder.h
@@ -26,7 +26,6 @@
 class CPDF_ContentParser;
 class CPDF_Document;
 class CPDF_PageObject;
-class CPDF_Stream;
 class PauseIndicatorIface;
 
 // These structs are used to keep track of resources that have already been
diff --git a/core/fpdfapi/parser/cpdf_linearized_header.h b/core/fpdfapi/parser/cpdf_linearized_header.h
index 44e0422..546e5a9 100644
--- a/core/fpdfapi/parser/cpdf_linearized_header.h
+++ b/core/fpdfapi/parser/cpdf_linearized_header.h
@@ -12,7 +12,6 @@
 #include "core/fxcrt/fx_system.h"
 
 class CPDF_Dictionary;
-class CPDF_Object;
 class CPDF_SyntaxParser;
 
 class CPDF_LinearizedHeader {
diff --git a/core/fpdfapi/parser/cpdf_object.h b/core/fpdfapi/parser/cpdf_object.h
index 06f8f64..a6b9136 100644
--- a/core/fpdfapi/parser/cpdf_object.h
+++ b/core/fpdfapi/parser/cpdf_object.h
@@ -21,7 +21,6 @@
 class CPDF_Encryptor;
 class CPDF_IndirectObjectHolder;
 class CPDF_Name;
-class CPDF_Null;
 class CPDF_Number;
 class CPDF_Reference;
 class CPDF_Stream;
diff --git a/core/fpdfapi/parser/cpdf_object_avail.h b/core/fpdfapi/parser/cpdf_object_avail.h
index 901fb17..a1dcc27 100644
--- a/core/fpdfapi/parser/cpdf_object_avail.h
+++ b/core/fpdfapi/parser/cpdf_object_avail.h
@@ -13,7 +13,6 @@
 #include "core/fxcrt/unowned_ptr.h"
 
 class CPDF_Object;
-class CPDF_Reference;
 class CPDF_IndirectObjectHolder;
 class CPDF_ReadValidator;
 
diff --git a/core/fpdfapi/parser/cpdf_parser.h b/core/fpdfapi/parser/cpdf_parser.h
index c9b590e..a2939cd 100644
--- a/core/fpdfapi/parser/cpdf_parser.h
+++ b/core/fpdfapi/parser/cpdf_parser.h
@@ -21,7 +21,6 @@
 #include "core/fxcrt/unowned_ptr.h"
 
 class CPDF_Array;
-class CPDF_CryptoHandler;
 class CPDF_Dictionary;
 class CPDF_LinearizedHeader;
 class CPDF_Object;
diff --git a/core/fpdfapi/parser/cpdf_security_handler.h b/core/fpdfapi/parser/cpdf_security_handler.h
index 280d92f..79f5ced 100644
--- a/core/fpdfapi/parser/cpdf_security_handler.h
+++ b/core/fpdfapi/parser/cpdf_security_handler.h
@@ -16,7 +16,6 @@
 
 class CPDF_Array;
 class CPDF_Dictionary;
-class CPDF_Parser;
 
 class CPDF_SecurityHandler : public Retainable {
  public:
diff --git a/core/fpdfapi/parser/cpdf_syntax_parser.h b/core/fpdfapi/parser/cpdf_syntax_parser.h
index d1778fd..e7319f9 100644
--- a/core/fpdfapi/parser/cpdf_syntax_parser.h
+++ b/core/fpdfapi/parser/cpdf_syntax_parser.h
@@ -18,7 +18,6 @@
 #include "core/fxcrt/unowned_ptr.h"
 #include "core/fxcrt/weak_ptr.h"
 
-class CPDF_CryptoHandler;
 class CPDF_Dictionary;
 class CPDF_IndirectObjectHolder;
 class CPDF_Object;
diff --git a/core/fpdfapi/render/cpdf_imagerenderer.h b/core/fpdfapi/render/cpdf_imagerenderer.h
index 4c3032f..d51e5f3 100644
--- a/core/fpdfapi/render/cpdf_imagerenderer.h
+++ b/core/fpdfapi/render/cpdf_imagerenderer.h
@@ -17,12 +17,10 @@
 #include "core/fxge/dib/fx_dib.h"
 #include "third_party/base/optional.h"
 
-class CFX_DIBitmap;
 class CFX_DIBBase;
 class CFX_DefaultRenderDevice;
 class CFX_ImageTransformer;
 class CPDF_ImageObject;
-class CPDF_PageObject;
 class CPDF_Pattern;
 class CPDF_RenderOptions;
 class CPDF_RenderStatus;
diff --git a/core/fpdfapi/render/cpdf_renderstatus.h b/core/fpdfapi/render/cpdf_renderstatus.h
index 0d273d0..d455ca6 100644
--- a/core/fpdfapi/render/cpdf_renderstatus.h
+++ b/core/fpdfapi/render/cpdf_renderstatus.h
@@ -38,7 +38,6 @@
 class CPDF_ShadingPattern;
 class CPDF_TilingPattern;
 class CPDF_TransferFunc;
-class CPDF_Type3Cache;
 class CPDF_Type3Char;
 class CPDF_Type3Font;
 class PauseIndicatorIface;
diff --git a/core/fpdfdoc/cpdf_apsettings.h b/core/fpdfdoc/cpdf_apsettings.h
index e141366..80b6107 100644
--- a/core/fpdfdoc/cpdf_apsettings.h
+++ b/core/fpdfdoc/cpdf_apsettings.h
@@ -15,7 +15,6 @@
 #include "core/fxge/dib/fx_dib.h"
 
 class CPDF_Dictionary;
-class CPDF_FormControl;
 class CPDF_Stream;
 
 // Corresponds to PDF spec section 12.5.6.19 (Widget annotation TP dictionary).
diff --git a/core/fpdfdoc/cpdf_formcontrol.h b/core/fpdfdoc/cpdf_formcontrol.h
index fbdfed1..c05acbb 100644
--- a/core/fpdfdoc/cpdf_formcontrol.h
+++ b/core/fpdfdoc/cpdf_formcontrol.h
@@ -29,8 +29,6 @@
 class CPDF_Font;
 class CPDF_FormField;
 class CPDF_InteractiveForm;
-class CPDF_OCContext;
-class CPDF_RenderOptions;
 class CPDF_Stream;
 
 class CPDF_FormControl {
diff --git a/core/fpdfdoc/cpdf_interactiveform.h b/core/fpdfdoc/cpdf_interactiveform.h
index 9bac8aa..1b27dfe 100644
--- a/core/fpdfdoc/cpdf_interactiveform.h
+++ b/core/fpdfdoc/cpdf_interactiveform.h
@@ -25,7 +25,6 @@
 class CPDF_Dictionary;
 class CPDF_Font;
 class CPDF_FormControl;
-class CPDF_Object;
 class CPDF_Page;
 
 class CPDF_InteractiveForm {
diff --git a/core/fpdfdoc/cpvt_section.h b/core/fpdfdoc/cpvt_section.h
index 407e47b..bd8ae00 100644
--- a/core/fpdfdoc/cpvt_section.h
+++ b/core/fpdfdoc/cpvt_section.h
@@ -20,7 +20,6 @@
 
 class CPVT_VariableText;
 struct CPVT_LineInfo;
-struct CPVT_WordLine;
 struct CPVT_WordPlace;
 
 class CPVT_Section final {
diff --git a/core/fpdftext/cpdf_textpage.h b/core/fpdftext/cpdf_textpage.h
index a03f3fb..ddc9413 100644
--- a/core/fpdftext/cpdf_textpage.h
+++ b/core/fpdftext/cpdf_textpage.h
@@ -19,7 +19,6 @@
 #include "core/fxcrt/unowned_ptr.h"
 #include "third_party/base/optional.h"
 
-class CPDF_Font;
 class CPDF_FormObject;
 class CPDF_Page;
 class CPDF_TextObject;
diff --git a/core/fxcodec/jbig2/JBig2_Context.h b/core/fxcodec/jbig2/JBig2_Context.h
index 6bc337d..11d104e 100644
--- a/core/fxcodec/jbig2/JBig2_Context.h
+++ b/core/fxcodec/jbig2/JBig2_Context.h
@@ -21,7 +21,6 @@
 
 class CJBig2_ArithDecoder;
 class CJBig2_GRDProc;
-class CPDF_StreamAcc;
 class PauseIndicatorIface;
 
 // Cache is keyed by the ObjNum of a stream and an index within the stream.
diff --git a/core/fxcodec/jbig2/jbig2_decoder.h b/core/fxcodec/jbig2/jbig2_decoder.h
index 91c78db..9b27417 100644
--- a/core/fxcodec/jbig2/jbig2_decoder.h
+++ b/core/fxcodec/jbig2/jbig2_decoder.h
@@ -13,7 +13,6 @@
 #include "third_party/base/span.h"
 
 class CJBig2_Context;
-class CJBig2_Image;
 class JBig2_DocumentContext;
 class PauseIndicatorIface;
 
diff --git a/core/fxcrt/xml/cfx_xmlparser.h b/core/fxcrt/xml/cfx_xmlparser.h
index ef171c6..7e1cba7 100644
--- a/core/fxcrt/xml/cfx_xmlparser.h
+++ b/core/fxcrt/xml/cfx_xmlparser.h
@@ -16,7 +16,6 @@
 
 class CFX_SeekableStreamProxy;
 class CFX_XMLDocument;
-class CFX_XMLElement;
 class CFX_XMLNode;
 class IFX_SeekableReadStream;
 
diff --git a/core/fxge/cfx_windowsrenderdevice.h b/core/fxge/cfx_windowsrenderdevice.h
index a356dc6..635c72b 100644
--- a/core/fxge/cfx_windowsrenderdevice.h
+++ b/core/fxge/cfx_windowsrenderdevice.h
@@ -21,7 +21,6 @@
   kModeEmfImageMasks = 6,
 };
 
-class RenderDeviceDriverIface;
 struct EncoderIface;
 
 #if defined(PDFIUM_PRINT_TEXT_WITH_GDI)
diff --git a/core/fxge/skia/fx_skia_device.h b/core/fxge/skia/fx_skia_device.h
index 1a68354..e44aa42 100644
--- a/core/fxge/skia/fx_skia_device.h
+++ b/core/fxge/skia/fx_skia_device.h
@@ -23,7 +23,6 @@
 class SkPictureRecorder;
 class SkiaState;
 class TextCharPos;
-struct SkIRect;
 
 class CFX_SkiaDeviceDriver final : public RenderDeviceDriverIface {
  public:
diff --git a/fxjs/xfa/cfxjse_engine.h b/fxjs/xfa/cfxjse_engine.h
index b09643c..9c83c0d 100644
--- a/fxjs/xfa/cfxjse_engine.h
+++ b/fxjs/xfa/cfxjse_engine.h
@@ -26,6 +26,7 @@
 class CFXJSE_FormCalcContext;
 class CFXJSE_HostObject;
 class CFXJSE_ResolveProcessor;
+class CFXJSE_Value;
 class CJS_Runtime;
 
 enum XFA_ResolveNode : uint16_t {
diff --git a/fxjs/xfa/cjx_eventpseudomodel.h b/fxjs/xfa/cjx_eventpseudomodel.h
index 1f55c44..39b6c08 100644
--- a/fxjs/xfa/cjx_eventpseudomodel.h
+++ b/fxjs/xfa/cjx_eventpseudomodel.h
@@ -10,7 +10,6 @@
 #include "fxjs/xfa/cjx_object.h"
 #include "fxjs/xfa/jse_define.h"
 
-class CFXJSE_Value;
 class CScript_EventPseudoModel;
 
 enum class XFA_Event {
diff --git a/fxjs/xfa/cjx_object.h b/fxjs/xfa/cjx_object.h
index 7dacd99..b23e87d 100644
--- a/fxjs/xfa/cjx_object.h
+++ b/fxjs/xfa/cjx_object.h
@@ -23,7 +23,6 @@
 #include "xfa/fxfa/fxfa_basic.h"
 
 class CFXJSE_MapModule;
-class CFXJSE_Value;
 class CFX_V8;
 class CFX_XMLElement;
 class CJX_Object;
diff --git a/fxjs/xfa/cjx_tree.h b/fxjs/xfa/cjx_tree.h
index 271558e..f18d0b7 100644
--- a/fxjs/xfa/cjx_tree.h
+++ b/fxjs/xfa/cjx_tree.h
@@ -11,7 +11,6 @@
 #include "fxjs/xfa/cjx_object.h"
 #include "fxjs/xfa/jse_define.h"
 
-class CFXJSE_Value;
 class CXFA_Object;
 class CXFA_Node;
 
diff --git a/fxjs/xfa/fxjse.h b/fxjs/xfa/fxjse.h
index fd7ff18..63646ab 100644
--- a/fxjs/xfa/fxjse.h
+++ b/fxjs/xfa/fxjse.h
@@ -23,7 +23,6 @@
 }  // namespace pdfium
 
 class CFXJSE_FormCalcContext;
-class CFXJSE_Value;
 class CJS_Result;
 class CJX_Object;
 
diff --git a/xfa/fxfa/parser/cxfa_box.h b/xfa/fxfa/parser/cxfa_box.h
index 330817d..1a361d5 100644
--- a/xfa/fxfa/parser/cxfa_box.h
+++ b/xfa/fxfa/parser/cxfa_box.h
@@ -17,7 +17,6 @@
 class CFGAS_GEGraphics;
 class CXFA_Edge;
 class CXFA_Fill;
-class CXFA_Margin;
 class CXFA_Stroke;
 
 class CXFA_Box : public CXFA_Node {
diff --git a/xfa/fxfa/parser/cxfa_fill.h b/xfa/fxfa/parser/cxfa_fill.h
index d1fa47c..2f7fb51 100644
--- a/xfa/fxfa/parser/cxfa_fill.h
+++ b/xfa/fxfa/parser/cxfa_fill.h
@@ -13,10 +13,6 @@
 #include "xfa/fxfa/parser/cxfa_node.h"
 
 class CFGAS_GEGraphics;
-class CXFA_Linear;
-class CXFA_Pattern;
-class CXFA_Radial;
-class CXFA_Stipple;
 
 class CXFA_Fill final : public CXFA_Node {
  public: