Add --enable-internal-media-session to trigger the MediaSession backend.

content/browser/media/session/media_session_controllers_manager.cc

 // Copyright 2016 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.
 
 #include "content/browser/media/session/media_session_controllers_manager.h"
 
 #include "base/command_line.h"
 #include "content/browser/media/session/media_session_controller.h"
 #include "media/base/media_switches.h"
 
 namespace content {
 
 namespace {
 
-bool IsDefaultMediaSessionEnabled() {
+bool IsMediaSessionEnabled() {
 #if defined(OS_ANDROID)
   return true;
 #else
-  return base::CommandLine::ForCurrentProcess()->HasSwitch(
-      switches::kEnableAudioFocus);
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  return command_line->HasSwitch(switches::kEnableInternalMediaSession) ||
+         command_line->HasSwitch(switches::kEnableAudioFocus);
 #endif
 }
 
 }  // anonymous namespace
 
 MediaSessionControllersManager::MediaSessionControllersManager(
     MediaWebContentsObserver* media_web_contents_observer)
     : media_web_contents_observer_(media_web_contents_observer) {
 }
 
 MediaSessionControllersManager::~MediaSessionControllersManager() = default;
 
 void MediaSessionControllersManager::RenderFrameDeleted(
     RenderFrameHost* render_frame_host) {
-  if (!IsDefaultMediaSessionEnabled())
+  if (!IsMediaSessionEnabled())
     return;
 
   for (auto it = controllers_map_.begin(); it != controllers_map_.end();) {
     if (it->first.first == render_frame_host)
       it = controllers_map_.erase(it);
     else
       ++it;
   }
 }
 
 bool MediaSessionControllersManager::RequestPlay(
     const MediaPlayerId& id,
     bool has_audio,
     bool is_remote,
     media::MediaContentType media_content_type) {
-  if (!IsDefaultMediaSessionEnabled())
+  if (!IsMediaSessionEnabled())
     return true;
 
   // Since we don't remove session instances on pause, there may be an existing
   // instance for this playback attempt.
   //
   // In this case, try to reinitialize it with the new settings.  If they are
   // the same, this is a no-op.  If the reinitialize fails, destroy the
   // controller. A later playback attempt will create a new controller.
   auto it = controllers_map_.find(id);
   if (it != controllers_map_.end()) {
     if (it->second->Initialize(has_audio, is_remote, media_content_type))
       return true;
     controllers_map_.erase(it);
     return false;
   }
 
   std::unique_ptr<MediaSessionController> controller(
       new MediaSessionController(id, media_web_contents_observer_));
 
   if (!controller->Initialize(has_audio, is_remote, media_content_type))
     return false;
 
   controllers_map_[id] = std::move(controller);
   return true;
 }
 
 void MediaSessionControllersManager::OnPause(const MediaPlayerId& id) {
-  if (!IsDefaultMediaSessionEnabled())
+  if (!IsMediaSessionEnabled())
     return;
 
   auto it = controllers_map_.find(id);
   if (it == controllers_map_.end())
     return;
 
   it->second->OnPlaybackPaused();
 }
 
 void MediaSessionControllersManager::OnEnd(const MediaPlayerId& id) {
-  if (!IsDefaultMediaSessionEnabled())
+  if (!IsMediaSessionEnabled())
     return;
   controllers_map_.erase(id);
 }
 
 }  // namespace content