Implement Audio Focus Manager for desktop.

content/content_tests.gypi

 # Copyright (c) 2013 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': {
     'layouttest_support_content_sources': [
       'public/test/layouttest_support.h',
       'public/test/nested_message_pump_android.cc',
       'public/test/nested_message_pump_android.h',
@@ skipping 512 matching lines @@
       'browser/mach_broker_mac_unittest.cc',
       'browser/media/audible_metrics_unittest.cc',
       'browser/media/audio_stream_monitor_unittest.cc',
       'browser/media/capture/audio_mirroring_manager_unittest.cc',
       'browser/media/capture/cursor_renderer_aura_unittest.cc',
       'browser/media/capture/web_contents_audio_input_stream_unittest.cc',
       'browser/media/capture/web_contents_video_capture_device_unittest.cc',
       'browser/media/cdm_service_impl_unittest.cc',
       'browser/media/media_internals_unittest.cc',
       'browser/media/midi_host_unittest.cc',
+      'browser/media/session/audio_focus_manager_unittest.cc',
       'browser/media/session/media_session_controller_unittest.cc',
       'browser/media/session/media_session_uma_helper_unittest.cc',
       'browser/net/quota_policy_cookie_store_unittest.cc',
       'browser/notification_service_impl_unittest.cc',
       'browser/notifications/notification_database_data_unittest.cc',
       'browser/notifications/notification_database_unittest.cc',
       'browser/notifications/notification_id_generator_unittest.cc',
       'browser/notifications/platform_notification_context_unittest.cc',
       'browser/notifications/type_converters_unittest.cc',
       'browser/power_monitor_message_broadcaster_unittest.cc',
@@ skipping 1398 matching lines @@
                   'content_unittests_apk.isolate',
                 ],
               },
             ],
           },
         ],
       ],
     }],
   ],
 }