Introduce NullVideoSink for test classes.

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 314 matching lines @@
         'base/media_log.h',
         'base/media_log_event.h',
         'base/media_permission.cc',
         'base/media_permission.h',
         'base/media_posix.cc',
         'base/media_switches.cc',
         'base/media_switches.h',
         'base/media_win.cc',
         'base/multi_channel_resampler.cc',
         'base/multi_channel_resampler.h',
+        'base/null_video_sink.cc',
+        'base/null_video_sink.h',
         'base/pipeline.cc',
         'base/pipeline.h',
         'base/pipeline_status.h',
         'base/player_tracker.cc',
         'base/player_tracker.h',
         'base/ranges.cc',
         'base/ranges.h',
         'base/renderer.cc',
         'base/renderer.h',
         'base/renderer_factory.cc',
@@ skipping 859 matching lines @@
         'base/container_names_unittest.cc',
         'base/data_buffer_unittest.cc',
         'base/decoder_buffer_queue_unittest.cc',
         'base/decoder_buffer_unittest.cc',
         'base/djb2_unittest.cc',
         'base/gmock_callback_support_unittest.cc',
         'base/key_systems_unittest.cc',
         'base/mac/video_frame_mac_unittests.cc',
         'base/media_file_checker_unittest.cc',
         'base/multi_channel_resampler_unittest.cc',
+        'base/null_video_sink_unittest.cc',
         'base/pipeline_unittest.cc',
         'base/ranges_unittest.cc',
         'base/run_all_unittests.cc',
         'base/seekable_buffer_unittest.cc',
         'base/serial_runner_unittest.cc',
         'base/sinc_resampler_unittest.cc',
         'base/stream_parser_unittest.cc',
         'base/text_ranges_unittest.cc',
         'base/text_renderer_unittest.cc',
         'base/time_delta_interpolator_unittest.cc',
@@ skipping 731 matching lines @@
             '../build/isolate.gypi',
           ],
           'sources': [
             'media_unittests.isolate',
           ],
         },
       ],
     }],
   ],
 }