Use chromium_code standard for PDFium GYP compilation

pdfium.gyp

 # Copyright 2015 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': {
-    # TODO(thakis): Enable this, pdfium:29
-    #'chromium_code': 1,
+    'chromium_code': 1,
 
     'variables': {
       'clang_use_pdfium_plugins%': 0,
     },
     'clang_use_pdfium_plugins%': '<(clang_use_pdfium_plugins)',
 
     'pdf_use_skia%': 0,
     'pdf_enable_v8%': 1,
     'pdf_enable_xfa%': 0, # Set to 1 by standalone.gypi in a standalone build.
     'conditions': [
@@ skipping 69 matching lines @@
       }],
       ['clang==1 and clang_use_pdfium_plugins==1', {
         'cflags': [
           '<@(clang_pdfium_plugins_flags)',
         ],
       }],
     ],
     'msvs_disabled_warnings': [
       4267,
     ],
-    'variables': {
-      'clang_warning_flags': [
-        # TODO(thestig): Fix all instances, remove this, pdfium:29
-        '-Wno-sign-compare',
-      ],
-      # Make sure Chromium's build/common.gypi doesn't re-add the flag on linux.
-      'cflags_cc!': [ '-Wsign-compare' ],
-    },
   },
   'targets': [
     {
       'target_name': 'pdfium',
       'type': 'static_library',
       'dependencies': [
         'third_party/third_party.gyp:bigint',
         'third_party/third_party.gyp:pdfium_base',
         'fdrm',
         'fpdfdoc',
@@ skipping 958 matching lines @@
             'fpdfsdk/fpdfxfa/include/fpdfxfa_app.h',
             'fpdfsdk/fpdfxfa/include/fpdfxfa_doc.h',
             'fpdfsdk/fpdfxfa/include/fpdfxfa_page.h',
             'fpdfsdk/fpdfxfa/include/fpdfxfa_util.h',
           ],
         },
       ]
     }],
   ]
 }