Do not build the Mock WebThemeEngine implementation on the Mac.

content/content_shell.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.
 
 {
   'variables': {
     'content_shell_product_name': 'Content Shell',
     # The "19" is so that sites that sniff for version think that this is
     # something reasonably current; the "77.34.5" is a hint that this isn't a
     # standard Chrome.
@@ skipping 235 matching lines @@
         'shell/renderer/webkit_test_runner.cc',
         'shell/renderer/webkit_test_runner.h',
         'test/layouttest_support.cc',
       ],
       'msvs_settings': {
         'VCLinkerTool': {
           'SubSystem': '2',  # Set /SUBSYSTEM:WINDOWS
         },
       },
       'conditions': [
+        ['OS=="mac"', {
+          'sources/': [
+            ['exclude', 'WebTestThemeEngineMock.cpp'],
+          ],
+        }],
         ['OS=="win" and win_use_allocator_shim==1', {
           'dependencies': [
             '../base/allocator/allocator.gyp:allocator',
           ],
         }],
         ['OS=="win"', {
           'resource_include_dirs': [
             '<(SHARED_INTERMEDIATE_DIR)/webkit',
           ],
           'dependencies': [
@@ skipping 852 matching lines @@
                 '--input_symbol', '<(PRODUCT_DIR)/content_shell.exe.pdb',
                 '--destination_dir', '<(dest_dir)',
               ],
             },
           ],
         },
       ],
     }],  # OS=="win" and fastbuild==0 and target_arch=="ia32"
   ]
 }