Remove _FX_PLATFORM_LINUX_.

Replace with defined(OS_LINUX) || defined(OS_ASMJS), or just
defined(OS_LINUX), as appropriate.

Change-Id: I20b205a571df68036bb2abc7dd20cb856c44b0b8
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/71451
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/core/fxcrt/fx_system.h b/core/fxcrt/fx_system.h
index c0bd83f..b71c88e 100644
--- a/core/fxcrt/fx_system.h
+++ b/core/fxcrt/fx_system.h
@@ -19,17 +19,6 @@
 
 #include "build/build_config.h"
 
-// _FX_PLATFORM_ values;
-#define _FX_PLATFORM_LINUX_ 2
-
-#if defined(_WIN32) || defined(_WIN64)
-#elif defined(__linux__)
-#define _FX_PLATFORM_ _FX_PLATFORM_LINUX_
-#elif defined(__APPLE__)
-#elif defined(__asmjs__) || defined(__wasm__)
-#define _FX_PLATFORM_ _FX_PLATFORM_LINUX_
-#endif
-
 #if defined(_MSC_VER) && _MSC_VER < 1900
 #error Sorry, VC++ 2015 or later is required to compile PDFium.
 #endif  // defined(_MSC_VER) && _MSC_VER < 1900
diff --git a/core/fxge/cfx_font.cpp b/core/fxge/cfx_font.cpp
index 0782c51..59fc8cb 100644
--- a/core/fxge/cfx_font.cpp
+++ b/core/fxge/cfx_font.cpp
@@ -221,7 +221,7 @@
     {FX_CHARSET_ShiftJIS, "MS Gothic"},
     {FX_CHARSET_Hangul, "Batang"},
     {FX_CHARSET_MSWin_Cyrillic, "Arial"},
-#if _FX_PLATFORM_ == _FX_PLATFORM_LINUX_ || defined(OS_MACOSX)
+#if defined(OS_LINUX) || defined(OS_ASMJS) || defined(OS_MACOSX)
     {FX_CHARSET_MSWin_EasternEuropean, "Arial"},
 #else
     {FX_CHARSET_MSWin_EasternEuropean, "Tahoma"},
diff --git a/core/fxge/cfx_fontmapper.cpp b/core/fxge/cfx_fontmapper.cpp
index 576b704..496d393 100644
--- a/core/fxge/cfx_fontmapper.cpp
+++ b/core/fxge/cfx_fontmapper.cpp
@@ -154,13 +154,13 @@
     {"ForteMT", "Forte"},
 };
 
-#if _FX_PLATFORM_ == _FX_PLATFORM_LINUX_
+#if defined(OS_LINUX) || defined(OS_ASMJS)
 const char kNarrowFamily[] = "LiberationSansNarrow";
 #elif defined(OS_ANDROID)
 const char kNarrowFamily[] = "RobotoCondensed";
 #else
 const char kNarrowFamily[] = "ArialNarrow";
-#endif  // _FX_PLATFORM_ == _FX_PLATFORM_LINUX_
+#endif  // defined(OS_LINUX) || defined(OS_ASMJS)
 
 ByteString TT_NormalizeName(const char* family) {
   ByteString norm(family);
diff --git a/xfa/fgas/font/cfx_fontsourceenum_file.cpp b/xfa/fgas/font/cfx_fontsourceenum_file.cpp
index 83283ec..d5a41cd 100644
--- a/xfa/fgas/font/cfx_fontsourceenum_file.cpp
+++ b/xfa/fgas/font/cfx_fontsourceenum_file.cpp
@@ -15,7 +15,7 @@
 constexpr char kFolderSeparator = '/';
 
 constexpr const char* kFontFolders[] = {
-#if _FX_PLATFORM_ == _FX_PLATFORM_LINUX_
+#if defined(OS_LINUX)
     "/usr/share/fonts",
     "/usr/share/X11/fonts/Type1",
     "/usr/share/X11/fonts/TTF",