NOT FOR LANDING Implement WebMediaSession

content/browser/media/media_web_contents_observer.cc

Index: content/browser/media/media_web_contents_observer.cc
diff --git a/content/browser/media/media_web_contents_observer.cc b/content/browser/media/media_web_contents_observer.cc
index b4e41ec12d0a10a89109cd0da8479d54e90610b8..1a621370fe75fe000fb125a116c1112cce82a44c 100644
--- a/content/browser/media/media_web_contents_observer.cc
+++ b/content/browser/media/media_web_contents_observer.cc
@@ -16,7 +16,9 @@
 #if defined(OS_ANDROID)
 #include "content/browser/android/media_players_observer.h"
 #include "content/browser/media/android/browser_media_player_manager.h"
+#include "content/browser/media/android/browser_media_session_manager.h"
 #include "content/common/media/media_player_messages_android.h"
+#include "content/common/media/media_session_messages_android.h"
 #include "media/base/android/media_player_android.h"
 #endif  // defined(OS_ANDROID)
 
@@ -38,6 +40,7 @@ void MediaWebContentsObserver::RenderFrameDeleted(
   // Always destroy the media players before CDMs because we do not support
   // detaching CDMs from media players yet. See http://crbug.com/330324
   media_player_managers_.erase(key);
+  media_session_managers_.erase(key);
 
   MediaPlayersObserver* audio_observer = GetMediaPlayersObserver();
   if (audio_observer)
@@ -112,6 +115,12 @@ bool MediaWebContentsObserver::OnMediaPlayerMessageReceived(
                         GetMediaPlayerManager(render_frame_host),
                         BrowserMediaPlayerManager::OnNotifyExternalSurface)
 #endif  // defined(VIDEO_HOLE)
+    IPC_MESSAGE_FORWARD(MediaSessionHostMsg_Activate,
+                        GetMediaSessionManager(render_frame_host),
+                        BrowserMediaSessionManager::OnActivate)
+    IPC_MESSAGE_FORWARD(MediaSessionHostMsg_Deactivate,
+                        GetMediaSessionManager(render_frame_host),
+                        BrowserMediaSessionManager::OnDeactivate)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   return handled;
@@ -171,6 +180,17 @@ BrowserMediaPlayerManager* MediaWebContentsObserver::GetMediaPlayerManager(
   return media_player_managers_.get(key);
 }
 
+BrowserMediaSessionManager* MediaWebContentsObserver::GetMediaSessionManager(
+    RenderFrameHost* render_frame_host) {
+  uintptr_t key = reinterpret_cast<uintptr_t>(render_frame_host);
+  if (!media_session_managers_.contains(key)) {
+    media_session_managers_.set(
+        key,
+        make_scoped_ptr(new BrowserMediaSessionManager(render_frame_host)));
+  }
+  return media_session_managers_.get(key);
+}
+
 MediaPlayersObserver*
 MediaWebContentsObserver::GetMediaPlayersObserver() const {
   AudioStateProvider* provider =