Implement MediaSession on top of the WebMediaPlayerDelegate.

content/common/frame_messages.h

Index: content/common/frame_messages.h
diff --git a/content/common/frame_messages.h b/content/common/frame_messages.h
index 0014c8a958705cfd2fb0ecf09b004a6cf47c7459..09d536f2c7dc7402f0f989f04d68cb774c861590 100644
--- a/content/common/frame_messages.h
+++ b/content/common/frame_messages.h
@@ -745,6 +745,12 @@ IPC_MESSAGE_ROUTED1(FrameMsg_SetTextTrackSettings,
 // Posts a message from a frame in another process to the current renderer.
 IPC_MESSAGE_ROUTED1(FrameMsg_PostMessageEvent, FrameMsg_PostMessage_Params)
 
+// Messages for pausing and initiating playback from the browser side.
+IPC_MESSAGE_ROUTED1(FrameMsg_MediaDelegatePause,
+                    int64_t /* player_cookie, distinguishes instances */)
+IPC_MESSAGE_ROUTED1(FrameMsg_MediaDelegatePlay,
+                    int64_t /* player_cookie, distinguishes instances */)
+
 #if defined(OS_ANDROID)
 
 // External popup menus.
@@ -1232,15 +1238,20 @@ IPC_MESSAGE_ROUTED2(FrameHostMsg_SetSelectedColorInColorChooser,
                     int /* id */,
                     SkColor /* color */)
 
+IPC_MESSAGE_ROUTED1(FrameHostMsg_MediaDestroyedNotification,
+                    int64_t /* player_cookie, distinguishes instances */)
+
 // Notifies the browser that media has started/stopped playing.
-IPC_MESSAGE_ROUTED4(FrameHostMsg_MediaPlayingNotification,
+IPC_MESSAGE_ROUTED5(FrameHostMsg_MediaPlayingNotification,
                     int64_t /* player_cookie, distinguishes instances */,
                     bool /* has_video */,
                     bool /* has_audio */,
-                    bool /* is_remote */)
+                    bool /* is_remote */,
+                    base::TimeDelta /* duration */)
 
-IPC_MESSAGE_ROUTED1(FrameHostMsg_MediaPausedNotification,
-                    int64_t /* player_cookie, distinguishes instances */)
+IPC_MESSAGE_ROUTED2(FrameHostMsg_MediaPausedNotification,
+                    int64_t /* player_cookie, distinguishes instances */,
+                    bool /* reached end of stream */)
 
 // Notify browser the theme color has been changed.
 IPC_MESSAGE_ROUTED1(FrameHostMsg_DidChangeThemeColor,