Rework composited scrolling updates.

Source/WebCore/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 291 matching lines @@
         if (Page* page = this->page())
             page->chrome()->client()->scheduleCompositingLayerFlush();
     }
 }
 
 bool RenderLayerCompositor::hasAnyAdditionalCompositedLayers(const RenderLayer* rootLayer) const
 {
     return m_compositedLayerCount > (rootLayer->isComposited() ? 1 : 0);
 }
 
+void RenderLayerCompositor::updateDescendantsAreContiguousInStackingOrderRecursive(RenderLayer* layer)
+{
+    for (RenderLayer* child = layer->firstChild(); child; child = child->nextSibling())
+        updateDescendantsAreContiguousInStackingOrderRecursive(child);
+    layer->updateDescendantDependentFlags();
+    layer->updateDescendantsAreContiguousInStackingOrder();
+}
+
+void RenderLayerCompositor::updateNeedsCompositedScrolling(RenderLayer* layer)
+{
+    layer->updateNeedsCompositedScrolling();
+
+    // These values depend on our composited scrolling status.
+    layer->updateIsNormalFlowOnly();
+    layer->updateSelfPaintingLayer();
+
+    for (RenderLayer* child = layer->firstChild(); child; child = child->nextSibling())
+        updateNeedsCompositedScrolling(child);
+}
+
+void RenderLayerCompositor::updateLayoutDependentState()
+{
+    RenderLayer* updateRoot = rootRenderLayer();
+    updateRoot->updateDescendantDependentFlags();
+    updateDescendantsAreContiguousInStackingOrderRecursive(updateRoot);
+    updateNeedsCompositedScrolling(updateRoot);
+}
+
 void RenderLayerCompositor::updateCompositingLayers(CompositingUpdateType updateType, RenderLayer* updateRoot)
 {
     // Avoid updating the layers with old values. Compositing layers will be updated after the layout is finished.
     if (m_renderView->needsLayout())
         return;
 
     if (m_forceCompositingMode && !m_compositing)
         enableCompositingMode(true);
 
     if (!m_reevaluateCompositingAfterLayout && !m_compositing)
@@ skipping 2461 matching lines @@
     info.addMember(m_layerForOverhangAreas, "layerForOverhangAreas");
     info.addMember(m_contentShadowLayer, "contentShadowLayer");
     info.addMember(m_layerForTopOverhangArea, "layerForTopOverhangArea");
     info.addMember(m_layerForBottomOverhangArea, "layerForBottomOverhangArea");
     info.addMember(m_layerForHeader, "layerForHeader");
     info.addMember(m_layerForFooter, "layerForFooter");
 #endif
 }
 
 } // namespace WebCore