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

content/content_common.gypi

 # 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.
 
 {
   'dependencies': [
     '../base/base.gyp:base',
     '../build/temp_gyp/googleurl.gyp:googleurl',
     '../gpu/gpu.gyp:gpu_ipc',
     '../ipc/ipc.gyp:ipc',
@@ skipping 158 matching lines @@
     'common/indexed_db_param_traits.cc',
     'common/indexed_db_param_traits.h',
     'common/intents_messages.h',
     'common/java_bridge_messages.h',
     'common/mac/attributed_string_coder.h',
     'common/mac/attributed_string_coder.mm',
     'common/mac/font_descriptor.h',
     'common/mac/font_descriptor.mm',
     'common/mac/font_loader.h',
     'common/mac/font_loader.mm',
-    'common/mac/scoped_sending_event.h',
-    'common/mac/scoped_sending_event.mm',
     'common/media/audio_messages.h',
     'common/media/audio_stream_state.h',
     'common/media/media_stream_messages.h',
     'common/media/media_stream_options.cc',
     'common/media/media_stream_options.h',
     'common/media/video_capture.h',
     'common/media/video_capture_messages.h',
     'common/message_router.cc',
     'common/message_router.h',
     'common/mime_registry_messages.h',
@@ skipping 124 matching lines @@
       ],
       'link_settings': {
         'libraries': [
           '-lEGL',
           '-lGLESv2',
         ],
       },
     }],
   ],
 }