Implement MediaSession on top of the WebMediaPlayerDelegate.

content/content_browser.gypi

 # 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.
 
 {
   'dependencies': [
     '../base/base.gyp:base_static',
     '../components/url_formatter/url_formatter.gyp:url_formatter',
     '../crypto/crypto.gyp:crypto',
     '../device/battery/battery.gyp:device_battery',
@@ skipping 972 matching lines @@
       'browser/media/android/browser_demuxer_android.cc',
       'browser/media/android/browser_demuxer_android.h',
       'browser/media/android/browser_media_player_manager.cc',
       'browser/media/android/browser_media_player_manager.h',
       'browser/media/android/browser_media_session_manager.cc',
       'browser/media/android/browser_media_session_manager.h',
       'browser/media/android/media_resource_getter_impl.cc',
       'browser/media/android/media_resource_getter_impl.h',
       'browser/media/android/media_session.cc',
       'browser/media/android/media_session.h',
+      'browser/media/android/media_session_controller.cc',
+      'browser/media/android/media_session_controller.h',
       'browser/media/android/media_session_observer.h',
       'browser/media/android/media_session_uma_helper.cc',
       'browser/media/android/media_session_uma_helper.h',
       'browser/media/android/media_throttler.cc',
       'browser/media/android/media_throttler.h',
       'browser/media/android/media_web_contents_observer_android.cc',
       'browser/media/android/media_web_contents_observer_android.h',
       'browser/media/android/provision_fetcher_impl.cc',
       'browser/media/android/provision_fetcher_impl.h',
       'browser/media/android/url_provision_fetcher.cc',
@@ skipping 1214 matching lines @@
     ['enable_webvr==1 and OS=="android"', {
       'sources': [
         'browser/vr/android/cardboard/cardboard_vr_device.cc',
         'browser/vr/android/cardboard/cardboard_vr_device.h',
         'browser/vr/android/cardboard/cardboard_vr_device_provider.cc',
         'browser/vr/android/cardboard/cardboard_vr_device_provider.h',
       ],
     }],
   ],
 }