Fix includes in fx_font.h.

Remove unused include and do IWYU.

Change-Id: Ia6c7a700f93c718db2b626a24cb95a5d8796c0e2
Reviewed-on: https://pdfium-review.googlesource.com/c/50078
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
diff --git a/core/fpdfapi/parser/cpdf_document.cpp b/core/fpdfapi/parser/cpdf_document.cpp
index 28e9b23..92dd9ae 100644
--- a/core/fpdfapi/parser/cpdf_document.cpp
+++ b/core/fpdfapi/parser/cpdf_document.cpp
@@ -31,6 +31,7 @@
 #include "core/fxcodec/JBig2_DocumentContext.h"
 #include "core/fxcrt/fx_codepage.h"
 #include "core/fxge/cfx_fontmapper.h"
+#include "core/fxge/cfx_substfont.h"
 #include "core/fxge/cfx_unicodeencoding.h"
 #include "core/fxge/fx_font.h"
 #include "third_party/base/ptr_util.h"
diff --git a/core/fxge/cfx_unicodeencoding.cpp b/core/fxge/cfx_unicodeencoding.cpp
index 446b62c..ecf1e72b 100644
--- a/core/fxge/cfx_unicodeencoding.cpp
+++ b/core/fxge/cfx_unicodeencoding.cpp
@@ -8,6 +8,7 @@
 
 #include "core/fxcrt/fx_codepage.h"
 #include "core/fxge/cfx_font.h"
+#include "core/fxge/cfx_substfont.h"
 #include "core/fxge/fx_font.h"
 #include "core/fxge/fx_freetype.h"
 
diff --git a/core/fxge/fx_font.h b/core/fxge/fx_font.h
index efaf411..5cf1bc2 100644
--- a/core/fxge/fx_font.h
+++ b/core/fxge/fx_font.h
@@ -10,8 +10,8 @@
 #include <vector>
 
 #include "core/fxcrt/fx_coordinates.h"
+#include "core/fxcrt/fx_string.h"
 #include "core/fxcrt/fx_system.h"
-#include "core/fxge/cfx_substfont.h"
 #include "core/fxge/fx_freetype.h"
 
 /* Font pitch and family flags */
diff --git a/xfa/fde/cfde_textout.cpp b/xfa/fde/cfde_textout.cpp
index 43d533c..517b541 100644
--- a/xfa/fde/cfde_textout.cpp
+++ b/xfa/fde/cfde_textout.cpp
@@ -13,6 +13,7 @@
 #include "core/fxcrt/fx_system.h"
 #include "core/fxge/cfx_font.h"
 #include "core/fxge/cfx_pathdata.h"
+#include "core/fxge/cfx_substfont.h"
 #include "core/fxge/fx_font.h"
 #include "third_party/base/ptr_util.h"
 #include "third_party/base/stl_util.h"