Client side display item cache flag

third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.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 1185 matching lines @@
 void CompositedLayerMapping::updateDrawsContent()
 {
     bool hasPaintedContent = containsPaintedContent();
     m_graphicsLayer->setDrawsContent(hasPaintedContent);
 
     if (m_scrollingLayer) {
         // m_scrollingLayer never has backing store.
         // m_scrollingContentsLayer only needs backing store if the scrolled contents need to paint.
         m_scrollingContentsAreEmpty = !m_owningLayer.hasVisibleContent() || !(layoutObject()->hasBackground() || layoutObject()->hasBackdropFilter() || paintsChildren());
         m_scrollingContentsLayer->setDrawsContent(!m_scrollingContentsAreEmpty);
+        m_graphicsLayer->setCanUseClientCacheStatus(false);
+        m_scrollingContentsLayer->setCanUseClientCacheStatus(true);
+    } else {
+        m_graphicsLayer->setCanUseClientCacheStatus(true);
     }
 
     if (hasPaintedContent && isAcceleratedCanvas(layoutObject())) {
         CanvasRenderingContext* context = toHTMLCanvasElement(layoutObject()->node())->renderingContext();
         // Content layer may be null if context is lost.
         if (WebLayer* contentLayer = context->platformLayer()) {
             Color bgColor(Color::transparent);
             if (contentLayerSupportsDirectBackgroundComposition(layoutObject())) {
                 bgColor = layoutObjectBackgroundColor();
                 hasPaintedContent = false;
@@ skipping 1360 matching lines @@
     } else if (graphicsLayer == m_scrollingContentsLayer.get()) {
         name = "Scrolling Contents Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace blink