ui: Cleanup class/struct forward declarations

chrome/browser/media/android/remote/remote_media_player_manager.h

Index: chrome/browser/media/android/remote/remote_media_player_manager.h
diff --git a/chrome/browser/media/android/remote/remote_media_player_manager.h b/chrome/browser/media/android/remote/remote_media_player_manager.h
index 2fd69279eb312e5ad4d30b05b911dc4e63daba97..0e1e6c7ffd7d22d685c5c030ff37d8373da15072 100644
--- a/chrome/browser/media/android/remote/remote_media_player_manager.h
+++ b/chrome/browser/media/android/remote/remote_media_player_manager.h
@@ -34,6 +34,9 @@ class RemoteMediaPlayerManager : public content::BrowserMediaPlayerManager {
   // Callback to trigger when a remote device has been unselected.
   void OnRemoteDeviceUnselected(int player_id);
 
+  // Callback to trigger when the video on a remote device starts playing.
+  void OnRemotePlaybackStarted(int player_id);
+
   // Callback to trigger when the video on a remote device finishes playing.
   void OnRemotePlaybackFinished(int player_id);