Let the WebMediaPlayer decide whether to use overlay video.

Source/core/layout/compositing/GraphicsLayerTreeBuilder.cpp

 /*
  * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2014 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.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 29 matching lines @@
 GraphicsLayerTreeBuilder::GraphicsLayerTreeBuilder()
 {
 }
 
 GraphicsLayerTreeBuilder::~GraphicsLayerTreeBuilder()
 {
 }
 
 static bool shouldAppendLayer(const DeprecatedPaintLayer& layer)
 {
-    if (!RuntimeEnabledFeatures::overlayFullscreenVideoEnabled())
-        return true;
     Node* node = layer.layoutObject()->node();
     if (node && isHTMLVideoElement(*node)) {
         HTMLVideoElement* element = toHTMLVideoElement(node);
-        // For WebRTC, video frame contains all the data and no hardware surface is used.
-        // We should always append the layer in this case.
-        if (element->isFullscreen() && !HTMLMediaElement::isMediaStreamURL(element->sourceURL().string()))
+        if (element->isFullscreen() && element->usesOverlayFullscreenVideo())
             return false;
     }
     return true;
 }
 
 void GraphicsLayerTreeBuilder::rebuild(DeprecatedPaintLayer& layer, AncestorInfo info)
 {
     // Make the layer compositing if necessary, and set up clipping and content layers.
     // Note that we can only do work here that is independent of whether the descendant layers
     // have been processed. computeCompositingRequirements() will already have done the paint invalidation if necessary.
@@ skipping 63 matching lines @@
     }
 
     if (layer.scrollParent()
         && layer.scrollParent()->hasCompositedDeprecatedPaintLayerMapping()
         && layer.scrollParent()->compositedDeprecatedPaintLayerMapping()->needsToReparentOverflowControls()
         && layer.scrollParent()->scrollableArea()->topmostScrollChild() == &layer)
         info.childLayersOfEnclosingCompositedLayer->append(layer.scrollParent()->compositedDeprecatedPaintLayerMapping()->detachLayerForOverflowControls(*info.enclosingCompositedLayer));
 }
 
 }