Use chromium_code standard for PDFium GYP compilation

third_party/third_party.gyp

 # Copyright 2014 PDFium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'variables': {
     'pdf_enable_xfa%': 0,  # Set to 1 by standalone.gypi in standalone builds.
     'pdf_use_skia%': 0,
   },
   'target_defaults': {
@@ skipping 67 matching lines @@
         'freetype/src/type1/type1.c',
       ],
       'conditions': [
         ['pdf_use_skia==1', {
           'sources': [
            'freetype/src/base/ftfntfmt.c',
            'freetype/src/base/ftfstype.c',
            'freetype/src/base/fttype1.c',
           ],
         }],
+        ['os_posix==1 and clang==0', {
+          'cflags': [
+            # open_face_PS_from_sfnt_stream() and open_face_from_buffer() in
+            # ftbase.h are unused. GCC needs this flag too.
+            '-Wno-unused-function',
+          ],
+        }],
       ],
       'variables': {
         'clang_warning_flags': [
           # open_face_PS_from_sfnt_stream() and open_face_from_buffer() in
           # ftbase.h are unused.
           '-Wno-unused-function',
         ],
       },
       'msvs_disabled_warnings': [
         # Warnings about conversion from 'size_t' to 'long', possible loss of
@@ skipping 17 matching lines @@
         'agg23/agg_rasterizer_scanline_aa.h',
         'agg23/agg_renderer_scanline.h',
         'agg23/agg_rendering_buffer.h',
         'agg23/agg_scanline_u.h',
         'agg23/agg_vcgen_dash.cpp',
         'agg23/agg_vcgen_stroke.cpp',
       ],
       'conditions': [
         ['os_posix==1', {
           # library contains several enum vs non-enum conditionals.
-          'cflags': [ '-Wno-extra', ],
+          'cflags': [ '-Wno-extra' ],
         }],
       ],
       'variables': {
         'clang_warning_flags': [
           # calc_butt_cap() in agg_vcgen_stroke.cpp is unused.
           '-Wno-unused-function',
         ],
       },
     },
     {
@@ skipping 291 matching lines @@
                 # tif_ojpeg.c and tif_jpeg.c.
                 'WIN32_LEAN_AND_MEAN',
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }