Implement CSSOM Smooth Scroll API

Source/core/rendering/RenderLayerCompositor.cpp

 /*
  * Copyright (C) 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
@@ skipping 2289 matching lines @@
         if (ScrollingCoordinator* scrollingCoordinator = this->scrollingCoordinator())
             scrollingCoordinator->setLayerIsContainerForFixedPositionLayers(m_scrollLayer.get(), true);
 
         // Hook them up
         m_overflowControlsHostLayer->addChild(m_containerLayer.get());
         m_containerLayer->addChild(m_scrollLayer.get());
         m_scrollLayer->addChild(m_rootContentLayer.get());
 
         frameViewDidChangeSize();
         frameViewDidScroll();
+        m_renderView->frameView()->layerForScrollingDidChange();
     }
 
     // Check to see if we have to change the attachment
     if (m_rootLayerAttachment != RootLayerUnattached)
         detachRootLayer();
 
     attachRootLayer(expectedAttachment);
 }
 
 void RenderLayerCompositor::destroyRootLayer()
@@ skipping 30 matching lines @@
 
     if (m_layerForScrollCorner) {
         m_layerForScrollCorner = nullptr;
         m_renderView->frameView()->invalidateScrollCorner(m_renderView->frameView()->scrollCornerRect());
     }
 
     if (m_overflowControlsHostLayer) {
         m_overflowControlsHostLayer = nullptr;
         m_containerLayer = nullptr;
         m_scrollLayer = nullptr;
+        m_renderView->frameView()->layerForScrollingDidChange();
     }
     ASSERT(!m_scrollLayer);
     m_rootContentLayer = nullptr;
 }
 
 void RenderLayerCompositor::attachRootLayer(RootLayerAttachment attachment)
 {
     if (!m_rootContentLayer)
         return;
 
@@ skipping 234 matching lines @@
     } else if (graphicsLayer == m_scrollLayer.get()) {
         name = "Frame Scrolling Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace WebCore