Set up clip and scroll parents on the blink side.

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 473 matching lines @@
     if (m_page->mainFrame()->view()->needsLayout())
         return;
 
     TRACE_EVENT0("input", "ScrollingCoordinator::touchEventTargetRectsDidChange");
 
     LayerHitTestRects touchEventTargetRects;
     computeTouchEventTargetRects(touchEventTargetRects);
     setTouchEventTargetRects(touchEventTargetRects);
 }
 
+void ScrollingCoordinator::updateScrollParentForLayer(RenderLayer* child, RenderLayer* parent)
+{
+    if (!child || !child->backing())
+        return;
+
+    WebLayer* childWebLayer = scrollingWebLayerForGraphicsLayer(child->layerForScrollChild());
+    if (!childWebLayer)
+        return;
+
+    WebLayer* scrollParentWebLayer = 0;
+    if (parent && parent->backing())
+        scrollParentWebLayer = scrollingWebLayerForGraphicsLayer(parent->backing()->parentForSublayers());
+
+    childWebLayer->setScrollParent(scrollParentWebLayer);
+}
+
+void ScrollingCoordinator::updateClipParentForLayer(RenderLayer* child, RenderLayer* parent)
+{
+    if (!child || !child->backing())
+        return;
+
+    WebLayer* childWebLayer = scrollingWebLayerForGraphicsLayer(child->backing()->graphicsLayer());
+    if (!childWebLayer)
+        return;
+
+    WebLayer* clipParentWebLayer = 0;
+    if (parent && parent->backing())
+        clipParentWebLayer = scrollingWebLayerForGraphicsLayer(parent->backing()->parentForSublayers());
+
+    childWebLayer->setClipParent(clipParentWebLayer);
+}
+
 void ScrollingCoordinator::willDestroyRenderLayer(RenderLayer* layer)
 {
     m_layersWithTouchRects.remove(layer);
 }
 
 void ScrollingCoordinator::setWheelEventHandlerCount(unsigned count)
 {
     if (WebLayer* scrollLayer = scrollingWebLayerForScrollableArea(m_page->mainFrame()->view()))
         scrollLayer->setHaveWheelEventHandlers(count > 0);
 }
@@ skipping 304 matching lines @@
         stringBuilder.resize(stringBuilder.length() - 2);
     return stringBuilder.toString();
 }
 
 String ScrollingCoordinator::mainThreadScrollingReasonsAsText() const
 {
     return mainThreadScrollingReasonsAsText(mainThreadScrollingReasons());
 }
 
 } // namespace WebCore