mac&ios: Do not disable CLANG_WARN_CXX0X_EXTENSIONS.

build/common.gypi

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 3862 matching lines @@
             ['clang==1', {
               'CC': '$(SOURCE_ROOT)/<(clang_dir)/clang',
               'LDPLUSPLUS': '$(SOURCE_ROOT)/<(clang_dir)/clang++',
 
               # gnu++11 instead of c++11 is needed because some code uses
               # typeof() (a GNU extension).
               # TODO(thakis): Eventually switch this to c++11 instead of
               # gnu++11 (once typeof can be removed, which is blocked on c++11
               # being available everywhere).
               'CLANG_CXX_LANGUAGE_STANDARD': 'gnu++11',  # -std=gnu++11
-              # Don't use -Wc++0x-extensions, which Xcode 4 enables by default
-              # when building with clang. This warning is triggered when the
-              # override keyword is used via the OVERRIDE macro from
-              # base/compiler_specific.h.
-              'CLANG_WARN_CXX0X_EXTENSIONS': 'NO',
               # Warn if automatic synthesis is triggered with
               # the -Wobjc-missing-property-synthesis flag.
               'CLANG_WARN_OBJC_MISSING_PROPERTY_SYNTHESIS': 'YES',
               'GCC_VERSION': 'com.apple.compilers.llvm.clang.1_0',
               'WARNING_CFLAGS': [
                 '-Wheader-hygiene',
 
                 # This warns on using ints as initializers for floats in
                 # initializer lists (e.g. |int a = f(); CGSize s = { a, a };|),
                 # which happens in several places in chrome code. Not sure if
@@ skipping 270 matching lines @@
         ],  # target_conditions
       },  # target_defaults
     }],  # OS=="mac"
     ['OS=="ios"', {
       'target_defaults': {
         'xcode_settings' : {
           'GCC_VERSION': 'com.apple.compilers.llvm.clang.1_0',
 
           # This next block is mostly common with the 'mac' section above,
           # but keying off (or setting) 'clang' isn't valid for iOS as it
-          # also seems to mean using the custom build of clang.
+          # also means using Chromium's build of clang.
 
           # TODO(stuartmorgan): switch to c++0x (see TODOs in the clang
           # section above).
           'CLANG_CXX_LANGUAGE_STANDARD': 'gnu++0x',
-          # Don't use -Wc++0x-extensions, which Xcode 4 enables by default
-          # when building with clang. This warning is triggered when the
-          # override keyword is used via the OVERRIDE macro from
-          # base/compiler_specific.h.
-          'CLANG_WARN_CXX0X_EXTENSIONS': 'NO',
           # Warn if automatic synthesis is triggered with
           # the -Wobjc-missing-property-synthesis flag.
           'CLANG_WARN_OBJC_MISSING_PROPERTY_SYNTHESIS': 'YES',
           'WARNING_CFLAGS': [
             '-Wheader-hygiene',
             # Don't die on dtoa code that uses a char as an array index.
             # This is required solely for base/third_party/dmg_fp/dtoa.cc.
             '-Wno-char-subscripts',
             # Clang spots more unused functions.
             '-Wno-unused-function',
@@ skipping 537 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }