[Mac] Move ScopedSendingEvent from content/common/mac to base/mac.

base/base.gyp

 # Copyright (c) 2011 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': {
     'chromium_code': 1,
   },
   'includes': [
     '../build/win_precompile.gypi',
@@ skipping 142 matching lines @@
         'json/json_reader_unittest.cc',
         'json/json_value_serializer_unittest.cc',
         'json/json_writer_unittest.cc',
         'json/string_escape_unittest.cc',
         'lazy_instance_unittest.cc',
         'linked_list_unittest.cc',
         'logging_unittest.cc',
         'mac/foundation_util_unittest.mm',
         'mac/mac_util_unittest.mm',
         'mac/objc_property_releaser_unittest.mm',
+        'mac/scoped_sending_event_unittest.mm',
         'md5_unittest.cc',
         'memory/linked_ptr_unittest.cc',
         'memory/mru_cache_unittest.cc',
         'memory/ref_counted_memory_unittest.cc',
         'memory/ref_counted_unittest.cc',
         'memory/scoped_ptr_unittest.cc',
         'memory/scoped_vector_unittest.cc',
         'memory/singleton_unittest.cc',
         'memory/weak_ptr_unittest.cc',
         'message_loop_proxy_impl_unittest.cc',
@@ skipping 273 matching lines @@
           'msvs_settings': {
             'VCLinkerTool': {
               'SubSystem': '2',         # Set /SUBSYSTEM:WINDOWS
             },
           },
         },
       ],
     }],
   ],
 }