Introduce media::TimeSource.

media/media.gyp

 # 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': {
     'chromium_code': 1,
     # Override to dynamically link the cras (ChromeOS audio) library.
     'use_cras%': 0,
     # Option e.g. for Linux distributions to link pulseaudio directly
@@ skipping 318 matching lines @@
         'base/text_cue.h',
         'base/text_ranges.cc',
         'base/text_ranges.h',
         'base/text_renderer.cc',
         'base/text_renderer.h',
         'base/text_track.h',
         'base/text_track_config.cc',
         'base/text_track_config.h',
         'base/time_delta_interpolator.cc',
         'base/time_delta_interpolator.h',
+        'base/time_source.h',
         'base/user_input_monitor.cc',
         'base/user_input_monitor.h',
         'base/user_input_monitor_linux.cc',
         'base/user_input_monitor_mac.cc',
         'base/user_input_monitor_win.cc',
         'base/video_decoder.cc',
         'base/video_decoder.h',
         'base/video_decoder_config.cc',
         'base/video_decoder_config.h',
         'base/video_frame.cc',
         'base/video_frame.h',
         'base/video_frame_pool.cc',
         'base/video_frame_pool.h',
         'base/video_renderer.cc',
         'base/video_renderer.h',
         'base/video_rotation.h',
         'base/video_util.cc',
         'base/video_util.h',
         'base/yuv_convert.cc',
         'base/yuv_convert.h',
+        'base/wall_clock_time_source.cc',
+        'base/wall_clock_time_source.h',
         'cdm/aes_decryptor.cc',
         'cdm/aes_decryptor.h',
         'cdm/json_web_key.cc',
         'cdm/json_web_key.h',
         'cdm/key_system_names.cc',
         'cdm/key_system_names.h',
         'cdm/player_tracker_impl.cc',
         'cdm/player_tracker_impl.h',
         'ffmpeg/ffmpeg_common.cc',
         'ffmpeg/ffmpeg_common.h',
@@ skipping 733 matching lines @@
         'base/stream_parser_unittest.cc',
         'base/text_ranges_unittest.cc',
         'base/text_renderer_unittest.cc',
         'base/time_delta_interpolator_unittest.cc',
         'base/user_input_monitor_unittest.cc',
         'base/vector_math_testing.h',
         'base/vector_math_unittest.cc',
         'base/video_frame_unittest.cc',
         'base/video_frame_pool_unittest.cc',
         'base/video_util_unittest.cc',
+        'base/wall_clock_time_source_unittest.cc',
         'base/yuv_convert_unittest.cc',
         'cdm/aes_decryptor_unittest.cc',
         'cdm/json_web_key_unittest.cc',
         'ffmpeg/ffmpeg_common_unittest.cc',
         'filters/audio_clock_unittest.cc',
         'filters/audio_decoder_unittest.cc',
         'filters/audio_decoder_selector_unittest.cc',
         'filters/audio_file_reader_unittest.cc',
         'filters/audio_renderer_algorithm_unittest.cc',
         'filters/audio_renderer_impl_unittest.cc',
@@ skipping 635 matching lines @@
                   ],
                 }],
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }