Improve GamepadSeqLock impl

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 117 matching lines @@
     'common/file_system_messages.h',
     'common/file_utilities_messages.h',
     'common/font_config_ipc_linux.cc',
     'common/font_config_ipc_linux.h',
     'common/font_list.h',
     'common/font_list_mac.mm',
     'common/font_list_win.cc',
     'common/font_list_x11.cc',
     'common/gamepad_hardware_buffer.h',
     'common/gamepad_messages.h',
-    'common/gamepad_seqlock.cc',
     'common/gamepad_seqlock.h',
     'common/geolocation_messages.h',
     'common/geoposition.cc',
     'common/geoposition.h',
     'common/gpu/gpu_channel.cc',
     'common/gpu/gpu_channel.h',
     'common/gpu/gpu_channel_manager.cc',
     'common/gpu/gpu_channel_manager.h',
     'common/gpu/gpu_command_buffer_stub.cc',
     'common/gpu/gpu_command_buffer_stub.h',
@@ skipping 170 matching lines @@
       ],
       'link_settings': {
         'libraries': [
           '-lEGL',
           '-lGLESv2',
         ],
       },
     }],
   ],
 }