Make MediaSession a runtime-enabled feature on Desktop.

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',
     '../cc/cc.gyp:cc',
     '../cc/cc.gyp:cc_surfaces',
     '../components/filesystem/filesystem.gyp:filesystem_lib',
@@ skipping 1004 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/browser_surface_view_manager.cc',
       'browser/media/android/browser_surface_view_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',
       'browser/media/android/url_provision_fetcher.h',
       'browser/media/audible_metrics.cc',
       'browser/media/audible_metrics.h',
@@ skipping 20 matching lines @@
       'browser/media/media_internals_handler.cc',
       'browser/media/media_internals_handler.h',
       'browser/media/media_internals_proxy.cc',
       'browser/media/media_internals_proxy.h',
       'browser/media/media_internals_ui.cc',
       'browser/media/media_internals_ui.h',
       'browser/media/media_web_contents_observer.cc',
       'browser/media/media_web_contents_observer.h',
       'browser/media/midi_host.cc',
       'browser/media/midi_host.h',
+      'browser/media/session/media_session.cc',
+      'browser/media/session/media_session.h',
+      'browser/media/session/media_session_controller.cc',
+      'browser/media/session/media_session_controller.h',
+      'browser/media/session/media_session_controllers_manager.cc',
+      'browser/media/session/media_session_controllers_manager.h',
+      'browser/media/session/media_session_delegate.h',
+      'browser/media/session/media_session_delegate_android.h',
+      'browser/media/session/media_session_delegate_android.cc',
+      'browser/media/session/media_session_delegate_default.cc',
+      'browser/media/session/media_session_observer.h',
+      'browser/media/session/media_session_uma_helper.cc',
+      'browser/media/session/media_session_uma_helper.h',
       'browser/media/webrtc/webrtc_identity_store.cc',
       'browser/media/webrtc/webrtc_identity_store.h',
       'browser/media/webrtc/webrtc_identity_store_backend.cc',
       'browser/media/webrtc/webrtc_identity_store_backend.h',
       'browser/memory/memory_message_filter.cc',
       'browser/memory/memory_message_filter.h',
       'browser/memory/memory_pressure_controller_impl.cc',
       'browser/memory/memory_pressure_controller_impl.h',
       'browser/message_port_message_filter.cc',
       'browser/message_port_message_filter.h',
@@ skipping 977 matching lines @@
       ],
       'sources': [
         '<@(android_browser_sources)',
         '<@(android_in_process_browser_sources)',
       ],
       'sources!': [
         'browser/browser_ipc_logging.cc',
         'browser/geolocation/device_data_provider.cc',
         'browser/geolocation/empty_device_data_provider.cc',
         'browser/geolocation/wifi_data_provider_common.cc',
+        'browser/media/session/media_session_delegate_default.cc',
         'browser/power_usage_monitor_impl.cc',
         'browser/power_usage_monitor_impl.h',
         'browser/renderer_host/begin_frame_observer_proxy.cc',
         'browser/renderer_host/native_web_keyboard_event.cc',
       ]
     }],
     ['OS=="mac"', {
       'sources/': [
         ['exclude', '^browser/device_sensors/data_fetcher_shared_memory_default.cc$'],
       ],
@@ skipping 112 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',
       ],
     }],
   ],
 }