Implement MediaSession (metadata) per frame [NOT READY, HAS DEPENDENCY]

content/browser/android/web_contents_observer_proxy.h

 // Copyright 2015 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.
 
 #ifndef CONTENT_BROWSER_ANDROID_WEB_CONTENTS_OBSERVER_PROXY_H_
 #define CONTENT_BROWSER_ANDROID_WEB_CONTENTS_OBSERVER_PROXY_H_
 
 #include <jni.h>
 
 #include "base/android/jni_weak_ref.h"
 #include "base/macros.h"
+#include "base/optional.h"

[whywhat, 2016/09/13 16:23:26]

nit: looks like an accidental change; should be in the file below?

[Zhiqiang Zhang (Slow), 2016/09/13 18:51:52]

Done.

 #include "base/process/kill.h"
 #include "content/browser/web_contents/web_contents_impl.h"
 #include "content/public/browser/reload_type.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/common/frame_navigate_params.h"
 #include "url/gurl.h"
 
 namespace content {
 
 class RenderViewHost;
@@ skipping 67 matching lines @@
   base::android::ScopedJavaGlobalRef<jobject> java_observer_;
   GURL base_url_of_last_started_data_url_;
 
   DISALLOW_COPY_AND_ASSIGN(WebContentsObserverProxy);
 };
 
 bool RegisterWebContentsObserverProxy(JNIEnv* env);
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_ANDROID_WEB_CONTENTS_OBSERVER_PROXY_H_