Add 'autoplay' content settings and expose it to Blink.

third_party/WebKit/Source/core/loader/FrameLoaderClient.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2012 Google 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 178 matching lines @@
     virtual void didUpdateCurrentHistoryItem() { }
     virtual void didRemoveAllPendingStylesheet() { }
 
     virtual bool allowScript(bool enabledPerSettings) { return enabledPerSettings; }
     virtual bool allowScriptFromSource(bool enabledPerSettings, const KURL&) { return enabledPerSettings; }
     virtual bool allowPlugins(bool enabledPerSettings) { return enabledPerSettings; }
     virtual bool allowImage(bool enabledPerSettings, const KURL&) { return enabledPerSettings; }
     virtual bool allowMedia(const KURL&) { return true; }
     virtual bool allowDisplayingInsecureContent(bool enabledPerSettings, const KURL&) { return enabledPerSettings; }
     virtual bool allowRunningInsecureContent(bool enabledPerSettings, SecurityOrigin*, const KURL&) { return enabledPerSettings; }
+    virtual bool allowAutoplay(bool defaultValue) { return defaultValue; }
 
     // This callback notifies the client that the frame was about to run
     // JavaScript but did not because allowScript returned false. We
     // have a separate callback here because there are a number of places
     // that need to know if JavaScript is enabled but are not necessarily
     // preparing to execute script.
     virtual void didNotAllowScript() { }
     // This callback is similar, but for plugins.
     virtual void didNotAllowPlugins() { }
 
@@ skipping 49 matching lines @@
         UnloadHandler,
     };
     virtual void suddenTerminationDisablerChanged(bool present, SuddenTerminationDisablerType) { }
 
     virtual LinkResource* createServiceWorkerLinkResource(HTMLLinkElement*) { return nullptr; }
 };
 
 } // namespace blink
 
 #endif // FrameLoaderClient_h