Implement autoplay gesture override experiment.

Source/core/layout/LayoutVideo.cpp

 /*
  * Copyright (C) 2007, 2008, 2009, 2010 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
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  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "core/layout/LayoutVideo.h"
 
 #include "core/HTMLNames.h"
 #include "core/dom/Document.h"
 #include "core/html/HTMLVideoElement.h"
 #include "core/layout/LayoutFullScreen.h"
+#include "core/layout/LayoutView.h"
 #include "core/paint/VideoPainter.h"
 #include "public/platform/WebLayer.h"
 
 namespace blink {
 
 using namespace HTMLNames;
 
 LayoutVideo::LayoutVideo(HTMLVideoElement* video)
     : LayoutMedia(video)
 {
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     if (element->isFullscreen() && element->usesOverlayFullscreenVideo())
         return CompositingReasonVideo;
 
     if (shouldDisplayVideo() && supportsAcceleratedRendering())
         return CompositingReasonVideo;
 
     return CompositingReasonNone;
 }
 
 } // namespace blink