Fix building android webview on arm64 on mac.

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 5109 matching lines @@
       },
     }],
     ['enable_new_npdevice_api==1', {
       'target_defaults': {
         'defines': [
           'ENABLE_NEW_NPDEVICE_API',
         ],
       },
     }],
     # Don't warn about the "typedef 'foo' locally defined but not used"
-    # for gcc 4.8.
+    # for gcc 4.8. We need a special case to handle the android webview build
+    # on mac because the host gcc there doesn't accept this flag, but the target
+    # gcc may require it.
     # TODO: remove this flag once all builds work. See crbug.com/227506
-    ['gcc_version>=48', {
+    ['gcc_version>=48 and (android_webview_build==0 or host_os!="mac")', {

[Nico, 2014/05/09 15:30:39]

I'd revert this part…

       'target_defaults': {
         'cflags': [
           '-Wno-unused-local-typedefs',
         ],
       },
     }],
+    ['gcc_version>=48 and android_webview_build==1 and host_os=="mac"', {

[Nico, 2014/05/09 15:30:39]

and instead do cflags! here and remove it again.

+      'target_defaults': {
+        'target_conditions': [
+          ['_toolset=="target"', {
+            'cflags': [
+              '-Wno-unused-local-typedefs',
+            ],
+          }],
+        ],
+      },
+    }],
     ['clang==1 and ((OS!="mac" and OS!="ios") or clang_xcode==0) '
         'and OS!="win"', {
       'make_global_settings': [
         ['CC', '<(make_clang_dir)/bin/clang'],
         ['CXX', '<(make_clang_dir)/bin/clang++'],
         ['CC.host', '$(CC)'],
         ['CXX.host', '$(CXX)'],
       ],
     }],
     ['clang==1 and OS=="win"', {
@@ skipping 95 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',
   },
 }