ui: Cleanup class/struct forward declarations

chrome/browser/media/android/remote/remote_media_player_bridge.cc

Index: chrome/browser/media/android/remote/remote_media_player_bridge.cc
diff --git a/chrome/browser/media/android/remote/remote_media_player_bridge.cc b/chrome/browser/media/android/remote/remote_media_player_bridge.cc
index 9806719a53dded5c38ccf656a45d149fde48e719..8a11cf5c344b3126c20fe7068ee155421dc4e4b1 100644
--- a/chrome/browser/media/android/remote/remote_media_player_bridge.cc
+++ b/chrome/browser/media/android/remote/remote_media_player_bridge.cc
@@ -180,6 +180,14 @@ void RemoteMediaPlayerBridge::OnCastStarting(
   }
 }
 
+void RemoteMediaPlayerBridge::OnCastStarted(
+    JNIEnv* env,
+    const JavaParamRef<jobject>& obj) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  static_cast<RemoteMediaPlayerManager*>(manager())->OnRemotePlaybackStarted(
+      player_id());
+}
+
 void RemoteMediaPlayerBridge::OnCastStopping(JNIEnv* env,
                                              const JavaParamRef<jobject>& obj) {
   static_cast<RemoteMediaPlayerManager*>(manager())