Let the WebMediaPlayer decide whether to use overlay video.

Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp

 /*
  * Copyright (C) 2009, 2010, 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:
  * 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
@@ skipping 741 matching lines @@
 
     FloatSize oldSize = m_graphicsLayer->size();
     const IntSize& contentsSize = relativeCompositingBounds.size();
     if (oldSize != contentsSize)
         m_graphicsLayer->setSize(contentsSize);
 
     // m_graphicsLayer is the corresponding GraphicsLayer for this DeprecatedPaintLayer and its non-compositing
     // descendants. So, the visibility flag for m_graphicsLayer should be true if there are any
     // non-compositing visible layers.
     bool contentsVisible = m_owningLayer.hasVisibleContent() || hasVisibleNonCompositingDescendant(&m_owningLayer);
-    if (RuntimeEnabledFeatures::overlayFullscreenVideoEnabled() && layoutObject()->isVideo()) {
+    if (layoutObject()->isVideo()) {
         HTMLVideoElement* videoElement = toHTMLVideoElement(layoutObject()->node());
-        if (videoElement->isFullscreen() && !HTMLMediaElement::isMediaStreamURL(videoElement->sourceURL().string()))
+        if (videoElement->isFullscreen() && videoElement->usesOverlayFullscreenVideo())
             contentsVisible = false;
     }
     m_graphicsLayer->setContentsVisible(contentsVisible);
 
     m_graphicsLayer->setBackfaceVisibility(layoutObject()->style()->backfaceVisibility() == BackfaceVisibilityVisible);
 }
 
 void CompositedDeprecatedPaintLayerMapping::computeGraphicsLayerParentLocation(const DeprecatedPaintLayer* compositingContainer, const IntRect& ancestorCompositingBounds, IntPoint& graphicsLayerParentLocation)
 {
     if (compositingContainer && compositingContainer->compositedDeprecatedPaintLayerMapping()->hasClippingLayer()) {
@@ skipping 1609 matching lines @@
     } else if (graphicsLayer == m_scrollingBlockSelectionLayer.get()) {
         name = "Scrolling Block Selection Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace blink