CompositedLayerMapping should use dirty bits for bounds update

Source/core/rendering/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 332 matching lines @@
     // so don't clip these, either.
     if (!compositor()->clippedByAncestor(&m_owningLayer))
         return true;
 
     if (m_owningLayer.renderer()->containingBlock()->enclosingLayer() != m_owningLayer.ancestorScrollingLayer())
         return true;
 
     return false;
 }
 
-void CompositedLayerMapping::updateCompositedBounds()
+void CompositedLayerMapping::updateCompositedBounds(GraphicsLayerUpdater::UpdateType updateType)
 {
+    if (!m_needToUpdateGeometry && updateType != GraphicsLayerUpdater::ForceUpdate)
+        return;
+
     // We need to know if we draw content in order to update our bounds (this has an effect
     // on whether or not descendands will paint into our backing). Update this value now.
     updateDrawsContent();
 
     LayoutRect layerBounds = compositor()->calculateCompositedBounds(&m_owningLayer, &m_owningLayer);
 
     // Clip to the size of the document or enclosing overflow-scroll layer.
     // If this or an ancestor is transformed, we can't currently compute the correct rect to intersect with.
     // We'd need RenderObject::convertContainerToLocalQuad(), which doesn't yet exist.
     if (shouldClipCompositedBounds()) {
@@ skipping 53 matching lines @@
 {
     RenderLayerCompositor* layerCompositor = compositor();
     if (!layerCompositor->compositingLayersNeedRebuild()) {
         // Calling updateGraphicsLayerGeometry() here gives incorrect results, because the
         // position of this layer's GraphicsLayer depends on the position of our compositing
         // ancestor's GraphicsLayer. That cannot be determined until all the descendant
         // RenderLayers of that ancestor have been processed via updateLayerPositions().
         //
         // The solution is to update compositing children of this layer here,
         // via updateCompositingChildrenGeometry().
-        updateCompositedBounds();
+        updateCompositedBounds(GraphicsLayerUpdater::ForceUpdate);
         layerCompositor->updateCompositingDescendantGeometry(m_owningLayer.stackingNode(), &m_owningLayer, flags & CompositingChildrenOnly);
 
         if (flags & IsUpdateRoot) {
             updateGraphicsLayerGeometry(GraphicsLayerUpdater::ForceUpdate);
             layerCompositor->updateRootLayerPosition();
             RenderLayerStackingNode* stackingContainer = m_owningLayer.stackingNode()->enclosingStackingContainerNode();
             if (!layerCompositor->compositingLayersNeedRebuild() && stackingContainer && (stackingContainer != m_owningLayer.stackingNode()))
                 layerCompositor->updateCompositingDescendantGeometry(stackingContainer, stackingContainer->layer(), flags & CompositingChildrenOnly);
         }
     }
@@ skipping 1707 matching lines @@
     } else if (graphicsLayer == m_scrollingContentsLayer.get()) {
         name = "Scrolling Contents Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace WebCore