Make MediaSession per frame as an attribute of Navigator

third_party/WebKit/Source/modules/mediasession/NavigatorMediaSession.h

+// Copyright 2016 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 NavigatorMediaSession_h
+#define NavigatorMediaSession_h
+
+#include "core/frame/DOMWindowProperty.h"

[mlamouri (slow - plz ping), 2016/10/10 20:30:35]

Do you need this include?

[Zhiqiang Zhang (Slow), 2016/10/11 10:56:04]

Removed.

+#include "core/frame/Navigator.h"
+#include "modules/mediasession/MediaSession.h"
+#include "platform/Supplementable.h"
+
+namespace blink {
+
+class Navigator;
+
+class NavigatorMediaSession final

[whywhat, 2016/10/10 20:45:10]

nit: don't forget to write comments to new classes (although might be rather
rudimentary in this case).

[Zhiqiang Zhang (Slow), 2016/10/11 10:56:04]

Done.

+    : public GarbageCollected<NavigatorMediaSession>,
+      public Supplement<Navigator> {
+  USING_GARBAGE_COLLECTED_MIXIN(NavigatorMediaSession);
+
+ public:
+  static NavigatorMediaSession& from(Navigator&);
+  static MediaSession* mediaSession(Navigator&);
+
+  DECLARE_TRACE();
+
+ private:
+  NavigatorMediaSession(Navigator&);
+  static const char* supplementName();
+
+  Member<MediaSession> m_session;
+};
+
+}  // namespace blink
+
+#endif  // NavigatorMediaSession_h