Merge 102611 - [chromium] Remove assumption that empty surface is always at end of list

Source/WebCore/platform/graphics/chromium/cc/CCLayerTreeHostCommon.cpp

 /*
  * Copyright (C) 2011 Google 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 416 matching lines @@
         // Compute the transformation matrix used to draw the replica of the render
         // surface.
         if (layer->replicaLayer()) {
             TransformationMatrix replicaDrawTransform = renderSurface->originTransform();
             replicaDrawTransform.translate3d(layer->replicaLayer()->position().x(), layer->replicaLayer()->position().y(), 0);
             replicaDrawTransform.multiply(layer->replicaLayer()->transform());
             replicaDrawTransform.translate3d(surfaceCenter.x() - anchorPoint.x() * bounds.width(), surfaceCenter.y() - anchorPoint.y() * bounds.height(), 0);
             renderSurface->setReplicaDrawTransform(replicaDrawTransform);
         }
 
-        // If a render surface has no layer list, then it and none of its
-        // children needed to get drawn. Therefore, it should be the last layer
-        // in the render surface list and we can trivially remove it.
+        // If a render surface has no layer list, then it and none of its children needed to get drawn.
         if (!layer->renderSurface()->layerList().size()) {
+            // FIXME: Originally we asserted that this layer was already at the end of the
+            //        list, and only needed to remove that layer. For now, we remove the
+            //        entire subtree of surfaces to fix a crash bug. The root cause is
+            //        https://bugs.webkit.org/show_bug.cgi?id=74147 and we should be able
+            //        to put the original assert after fixing that.
+            while (renderSurfaceLayerList.last() != layer) {
+                renderSurfaceLayerList.last()->clearRenderSurface();
+                renderSurfaceLayerList.removeLast();
+            }
             ASSERT(renderSurfaceLayerList.last() == layer);
             renderSurfaceLayerList.removeLast();
             layer->clearRenderSurface();
             return false;
         }
     }
 
     // If neither this layer nor any of its children were added, early out.
     if (sortingStartIndex == descendants.size())
         return false;
@@ skipping 32 matching lines @@
     walkLayersAndCalculateVisibleLayerRects<LayerChromium, RenderSurfaceChromium>(renderSurfaceLayerList);
 }
 
 void CCLayerTreeHostCommon::calculateDrawTransformsAndVisibility(CCLayerImpl* layer, CCLayerImpl* rootLayer, const TransformationMatrix& parentMatrix, const TransformationMatrix& fullHierarchyMatrix, Vector<RefPtr<CCLayerImpl> >& renderSurfaceLayerList, Vector<RefPtr<CCLayerImpl> >& layerList, CCLayerSorter* layerSorter, int maxTextureSize)
 {
     calculateDrawTransformsAndVisibilityInternal<CCLayerImpl, CCRenderSurface, CCLayerSorter>(layer, rootLayer, parentMatrix, fullHierarchyMatrix, renderSurfaceLayerList, layerList, layerSorter, maxTextureSize);
     walkLayersAndCalculateVisibleLayerRects<CCLayerImpl, CCRenderSurface>(renderSurfaceLayerList);
 }
 
 } // namespace WebCore