Adds USB writing for OS X.

chrome/chrome_utility.gypi

 # Copyright 2014 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.
 
 {
   'targets': [
     {
       'target_name': 'utility',
       'type': 'static_library',
       'variables': { 'enable_wexit_time_destructors': 1, },
@@ skipping 22 matching lines @@
         'utility/chrome_content_utility_client.cc',
         'utility/chrome_content_utility_client.h',
         'utility/chrome_content_utility_ipc_whitelist.cc',
         'utility/chrome_content_utility_ipc_whitelist.h',
         'utility/cloud_print/bitmap_image.cc',
         'utility/cloud_print/bitmap_image.h',
         'utility/cloud_print/pwg_encoder.cc',
         'utility/cloud_print/pwg_encoder.h',
         'utility/extensions/unpacker.cc',
         'utility/extensions/unpacker.h',
+        'utility/image_writer/disk_unmounter_mac.cc',
+        'utility/image_writer/disk_unmounter_mac.h',
         'utility/image_writer/error_messages.cc',
         'utility/image_writer/error_messages.h',
         'utility/image_writer/image_writer.cc',
         'utility/image_writer/image_writer.h',
         'utility/image_writer/image_writer_handler.cc',
         'utility/image_writer/image_writer_handler.h',
+        'utility/image_writer/image_writer_mac.cc',
         'utility/image_writer/image_writer_win.cc',
         'utility/importer/bookmark_html_reader.cc',
         'utility/importer/bookmark_html_reader.h',
         'utility/importer/bookmarks_file_importer.cc',
         'utility/importer/bookmarks_file_importer.h',
         'utility/importer/external_process_importer_bridge.cc',
         'utility/importer/external_process_importer_bridge.h',
         'utility/importer/favicon_reencode.cc',
         'utility/importer/favicon_reencode.h',
         'utility/importer/firefox_importer.cc',
@@ skipping 73 matching lines @@
             ['exclude', '^utility/media_galleries/'],
             ['exclude', '^utility/profile_import_handler\.cc'],
           ],
         }],
         ['enable_mdns == 1', {
           'sources': [
             'utility/local_discovery/service_discovery_message_handler.cc',
             'utility/local_discovery/service_discovery_message_handler.h',
           ]
         }],
-        ['OS!="win"', {
+        ['OS!="win" and OS!="mac"', {
           'sources': [
             'utility/image_writer/image_writer_stub.cc',
           ]
         }],
       ],
       # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
       'msvs_disabled_warnings': [ 4267, ],
     },
   ],
 }