NOT FOR LANDING Introduce and use WebMediaSession

Source/web/FrameLoaderClientImpl.h

 /*
  * Copyright (C) 2009, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 108 matching lines @@
     WTF::String userAgent(const KURL&) override;
     WTF::String doNotTrackValue() override;
     void transitionToCommittedForNewPage() override;
     PassRefPtrWillBeRawPtr<LocalFrame> createFrame(const FrameLoadRequest&, const WTF::AtomicString& name, HTMLFrameOwnerElement*) override;
     virtual bool canCreatePluginWithoutRenderer(const String& mimeType) const;
     PassRefPtrWillBeRawPtr<Widget> createPlugin(
         HTMLPlugInElement*, const KURL&,
         const Vector<WTF::String>&, const Vector<WTF::String>&,
         const WTF::String&, bool loadManually, DetachedPluginPolicy) override;
     PassOwnPtr<WebMediaPlayer> createWebMediaPlayer(HTMLMediaElement&, const WebURL&, WebMediaPlayerClient*) override;
+    PassOwnPtr<WebMediaSession> createWebMediaSession() override;
     ObjectContentType objectContentType(
         const KURL&, const WTF::String& mimeType, bool shouldPreferPlugInsForImages) override;
     void didChangeScrollOffset() override;
     void didUpdateCurrentHistoryItem() override;
     void didRemoveAllPendingStylesheet() override;
     bool allowScript(bool enabledPerSettings) override;
     bool allowScriptFromSource(bool enabledPerSettings, const KURL& scriptURL) override;
     bool allowPlugins(bool enabledPerSettings) override;
     bool allowImage(bool enabledPerSettings, const KURL& imageURL) override;
     bool allowMedia(const KURL& mediaURL) override;
@@ skipping 45 matching lines @@
     // The WebFrame that owns this object and manages its lifetime. Therefore,
     // the web frame object is guaranteed to exist.
     RawPtrWillBeMember<WebLocalFrameImpl> m_webFrame;
 };
 
 DEFINE_TYPE_CASTS(FrameLoaderClientImpl, FrameLoaderClient, client, client->isFrameLoaderClientImpl(), client.isFrameLoaderClientImpl());
 
 } // namespace blink
 
 #endif