Added stub MediaSourcePlayer for developing behind the flag

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 1759 matching lines @@
           'variables': {
             'jni_gen_package': 'media',
           },
           'includes': ['../build/jni_generator.gypi'],
         },
         {
           # GN: //media/base/android:android
           'target_name': 'player_android',
           'type': 'static_library',
           'sources': [
+            'base/android/mt/player.cc',
+            'base/android/mt/player.h',
             'base/android/audio_decoder_job.cc',
             'base/android/audio_decoder_job.h',
             'base/android/browser_cdm_factory_android.cc',
             'base/android/browser_cdm_factory_android.h',
             'base/android/demuxer_android.h',
             'base/android/demuxer_stream_player_params.cc',
             'base/android/demuxer_stream_player_params.h',
             'base/android/media_codec_bridge.cc',
             'base/android/media_codec_bridge.h',
             'base/android/media_common_android.h',
@@ skipping 202 matching lines @@
             '../build/isolate.gypi',
           ],
           'sources': [
             'media_unittests.isolate',
           ],
         },
       ],
     }],
   ],
 }