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 305 matching lines @@
 void RenderLayerCompositor::updateCompositingLayersTimerFired(Timer<RenderLayerCompositor>*)
 {
     updateCompositingLayers(CompositingUpdateAfterLayout);
 }
 
 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);
+
+    if (layer->isStackingContext() && layer->m_descendantsAreContiguousInStackingOrderDirty)
+        layer->updateDescendantsAreContiguousInStackingOrder();
+}
+
+void RenderLayerCompositor::updateNeedsCompositedScrolling(RenderLayer* layer)
+{
+    layer->updateNeedsCompositedScrolling();
+    for (RenderLayer* child = layer->firstChild(); child; child = child->nextSibling())
+        updateNeedsCompositedScrolling(child);
+}
+
 void RenderLayerCompositor::updateCompositingLayers(CompositingUpdateType updateType, RenderLayer* updateRoot)
 {
     m_updateCompositingLayersTimer.stop();
     
     // 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);
@@ skipping 40 matching lines @@
 
 #if !LOG_DISABLED
     double startTime = 0;
     if (compositingLogEnabled()) {
         ++m_rootLayerUpdateCount;
         startTime = currentTime();
     }
 #endif
 
     if (checkForHierarchyUpdate) {
+        // FIXME(vollick): can we skip this altogether in some cases?
+        updateRoot->updateDescendantDependentFlags();
+        updateDescendantsAreContiguousInStackingOrderRecursive(updateRoot);
+        updateNeedsCompositedScrolling(updateRoot);
+
         // Go through the layers in presentation order, so that we can compute which RenderLayers need compositing layers.
         // FIXME: we could maybe do this and the hierarchy udpate in one pass, but the parenting logic would be more complex.
         CompositingState compState(updateRoot, m_compositingConsultsOverlap);
         bool layersChanged = false;
         bool saw3DTransform = false;
         {
             TRACE_EVENT0("blink_rendering", "RenderLayerCompositor::computeCompositingRequirements");
             if (m_compositingConsultsOverlap) {
                 OverlapMap overlapTestRequestMap;
                 computeCompositingRequirements(0, updateRoot, &overlapTestRequestMap, compState, layersChanged, saw3DTransform);
@@ skipping 2415 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