Implement CSSOM Smooth Scroll API

Source/core/page/scrolling/ScrollingCoordinator.cpp

 /*
  * Copyright (C) 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 362 matching lines @@
         GraphicsLayer* horizontalScrollbarLayer = horizontalScrollbarLayerForScrollableArea(scrollableArea);
         if (horizontalScrollbarLayer)
             setupScrollbarLayer(horizontalScrollbarLayer, scrollbarLayer, webLayer, containerLayer);
     }
     if (WebScrollbarLayer* scrollbarLayer = getWebScrollbarLayer(scrollableArea, VerticalScrollbar)) {
         GraphicsLayer* verticalScrollbarLayer = verticalScrollbarLayerForScrollableArea(scrollableArea);
         if (verticalScrollbarLayer)
             setupScrollbarLayer(verticalScrollbarLayer, scrollbarLayer, webLayer, containerLayer);
     }
 
+    scrollableArea->layerForScrollingDidChange();
     return !!webLayer;
 }
 
 // In order to do a DFS cross-frame walk of the RenderLayer tree, we need to know which
 // RenderLayers have child frames inside of them. This computes a mapping for the
 // current frame which we can consult while walking the layers of that frame.
 // Whenever we descend into a new frame, a new map will be created.
 typedef HashMap<const RenderLayer*, Vector<const Frame*> > LayerFrameMap;
 static void makeLayerChildFrameMap(const Frame* currentFrame, LayerFrameMap* map)
 {
@@ skipping 237 matching lines @@
 
 void ScrollingCoordinator::recomputeWheelEventHandlerCountForFrameView(FrameView*)
 {
     setWheelEventHandlerCount(computeCurrentWheelEventHandlerCount());
 }
 
 void ScrollingCoordinator::setShouldUpdateScrollLayerPositionOnMainThread(MainThreadScrollingReasons reasons)
 {
     if (WebLayer* scrollLayer = scrollingWebLayerForScrollableArea(m_page->mainFrame()->view())) {
         m_lastMainThreadScrollingReasons = reasons;
-        scrollLayer->setShouldScrollOnMainThread(reasons);
+        bool shouldScrollOnMainThread = reasons;
+        if (shouldScrollOnMainThread != scrollLayer->shouldScrollOnMainThread()) {
+            scrollLayer->setShouldScrollOnMainThread(reasons);
+            m_page->mainFrame()->view()->requiresMainThreadScrollingDidChange();
+        }
     }
 }
 
 void ScrollingCoordinator::pageDestroyed()
 {
     ASSERT(m_page);
     m_page = 0;
 }
 
 bool ScrollingCoordinator::coordinatesScrollingForFrameView(FrameView* frameView) const
@@ skipping 317 matching lines @@
     bool frameIsScrollable = frameView && frameView->isScrollable();
     if (frameIsScrollable != m_wasFrameScrollable)
         return true;
 
     if (WebLayer* scrollLayer = frameView ? scrollingWebLayerForScrollableArea(frameView) : 0)
         return blink::WebSize(frameView->contentsSize()) != scrollLayer->bounds();
     return false;
 }
 
 } // namespace WebCore