Revert 114283 - Avoid using backing store for compositing layers that just need to clip

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 566 matching lines @@
     setCompositingLayersNeedRebuild();
 }
 
 void RenderLayerCompositor::layerWillBeRemoved(RenderLayer* parent, RenderLayer* child)
 {
     if (!child->isComposited() || parent->renderer()->documentBeingDestroyed())
         return;
 
     setCompositingParent(child, 0);
     
-    RenderLayer* compLayer = parent->enclosingCompositingLayerForRepaint();
+    RenderLayer* compLayer = parent->enclosingCompositingLayer();
     if (compLayer) {
         ASSERT(compLayer->backing());
         LayoutRect compBounds = child->backing()->compositedBounds();
 
         LayoutPoint offset;
         child->convertToLayerCoords(compLayer, offset);
         compBounds.moveBy(offset);
 
         compLayer->setBackingNeedsRepaintInRect(compBounds);
 
@@ skipping 598 matching lines @@
 
 
 void RenderLayerCompositor::repaintCompositedLayersAbsoluteRect(const IntRect& absRect)
 {
     recursiveRepaintLayerRect(rootRenderLayer(), absRect);
 }
 
 void RenderLayerCompositor::recursiveRepaintLayerRect(RenderLayer* layer, const IntRect& rect)
 {
     // FIXME: This method does not work correctly with transforms.
-    if (layer->isComposited() && !layer->backing()->paintsIntoCompositedAncestor())
+    if (layer->isComposited())
         layer->setBackingNeedsRepaintInRect(rect);
 
 #if !ASSERT_DISABLED
     LayerListMutationDetector mutationChecker(layer);
 #endif
 
     if (layer->hasCompositingDescendant()) {
         if (Vector<RenderLayer*>* negZOrderList = layer->negZOrderList()) {
             size_t listSize = negZOrderList->size();
             for (size_t i = 0; i < listSize; ++i) {
@@ skipping 174 matching lines @@
 bool RenderLayerCompositor::requiresCompositingLayer(const RenderLayer* layer) const
 {
     RenderObject* renderer = layer->renderer();
     // The compositing state of a reflection should match that of its reflected layer.
     if (layer->isReflection()) {
         renderer = renderer->parent(); // The RenderReplica's parent is the object being reflected.
         layer = toRenderBoxModelObject(renderer)->layer();
     }
     // The root layer always has a compositing layer, but it may not have backing.
     return requiresCompositingForTransform(renderer)
-        || requiresCompositingForVideo(renderer)
-        || requiresCompositingForCanvas(renderer)
-        || requiresCompositingForPlugin(renderer)
-        || requiresCompositingForFrame(renderer)
-        || (canRender3DTransforms() && renderer->style()->backfaceVisibility() == BackfaceVisibilityHidden)
-        || clipsCompositingDescendants(layer)
-        || requiresCompositingForAnimation(renderer)
-        || requiresCompositingForFilters(renderer)
-        || requiresCompositingForPosition(renderer, layer);
+             || requiresCompositingForVideo(renderer)
+             || requiresCompositingForCanvas(renderer)
+             || requiresCompositingForPlugin(renderer)
+             || requiresCompositingForFrame(renderer)
+             || (canRender3DTransforms() && renderer->style()->backfaceVisibility() == BackfaceVisibilityHidden)
+             || clipsCompositingDescendants(layer)
+             || requiresCompositingForAnimation(renderer)
+             || requiresCompositingForFilters(renderer)
+             || requiresCompositingForPosition(renderer, layer);
 }
 
 bool RenderLayerCompositor::canBeComposited(const RenderLayer* layer) const
 {
     return m_hasAcceleratedCompositing && layer->isSelfPaintingLayer();
 }
 
-bool RenderLayerCompositor::requiresOwnBackingStore(const RenderLayer* layer, const RenderLayer* compositingAncestorLayer) const
-{
-    RenderObject* renderer = layer->renderer();
-    if (compositingAncestorLayer
-        && !(compositingAncestorLayer->backing()->graphicsLayer()->drawsContent()
-            || compositingAncestorLayer->backing()->paintsIntoWindow()
-            || compositingAncestorLayer->backing()->paintsIntoCompositedAncestor()))
-        return true;
-
-    return layer->isRootLayer()
-        || layer->transform() // note: excludes perspective and transformStyle3D.
-        || requiresCompositingForVideo(renderer)
-        || requiresCompositingForCanvas(renderer)
-        || requiresCompositingForPlugin(renderer)
-        || requiresCompositingForFrame(renderer)
-        || (canRender3DTransforms() && renderer->style()->backfaceVisibility() == BackfaceVisibilityHidden)
-        || requiresCompositingForAnimation(renderer)
-        || requiresCompositingForFilters(renderer)
-        || requiresCompositingForPosition(renderer, layer)
-        || renderer->isTransparent()
-        || renderer->hasMask()
-        || renderer->hasReflection()
-        || renderer->hasFilter()
-        || layer->mustOverlapCompositedLayers();
-}
-
 #if !LOG_DISABLED
 const char* RenderLayerCompositor::reasonForCompositing(const RenderLayer* layer)
 {
     RenderObject* renderer = layer->renderer();
     if (layer->isReflection()) {
         renderer = renderer->parent();
         layer = toRenderBoxModelObject(renderer)->layer();
     }
 
     if (renderer->hasTransform() && renderer->style()->hasPerspective())
@@ skipping 833 matching lines @@
         if (Page* page = frame->page())
             return page->scrollingCoordinator();
     }
 
     return 0;
 }
 
 } // namespace WebCore
 
 #endif // USE(ACCELERATED_COMPOSITING)