Merge 112436 - [chromium] layer->clipRect() is not initialized for layers that create a renderSurfa…

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 352 matching lines @@
         layer->setScreenSpaceTransformIsAnimating(layerIsInAnimatingSubtreeForScreen);
 
         // Update the aggregate hierarchy matrix to include the transform of the newly created RenderSurface.
         nextHierarchyMatrix.multiply(surfaceOriginTransform);
 
         // The render surface clipRect contributes to the scissor rect that needs to
         // be applied before drawing the render surface onto its containing
         // surface and is therefore expressed in the parent's coordinate system.
         renderSurface->setClipRect(layer->parent() ? layer->parent()->clipRect() : layer->clipRect());
 
+        // The layer's clipRect can be reset here. The renderSurface will correctly clip the subtree.
+        layer->setUsesLayerClipping(false);
+        layer->setClipRect(IntRect());
+
         if (layer->maskLayer()) {
             renderSurface->setMaskLayer(layer->maskLayer());
             layer->maskLayer()->setTargetRenderSurface(renderSurface);
         } else
             renderSurface->setMaskLayer(0);
 
         if (layer->replicaLayer() && layer->replicaLayer()->maskLayer())
             layer->replicaLayer()->maskLayer()->setTargetRenderSurface(renderSurface);
 
         renderSurface->setFilters(layer->filters());
@@ skipping 16 matching lines @@
             layer->clearRenderSurface();
 
             // Layers inherit the clip rect from their parent.
             layer->setClipRect(layer->parent()->clipRect());
             if (layer->parent()->usesLayerClipping())
                 layer->setUsesLayerClipping(true);
 
             // Layers without their own renderSurface will render into the nearest ancestor surface.
             layer->setTargetRenderSurface(layer->parent()->targetRenderSurface());
         }
+    }
 
-        if (layer->masksToBounds()) {
-            IntRect clipRect = transformedLayerRect;
+    if (layer->masksToBounds()) {
+        IntRect clipRect = transformedLayerRect;
+
+        // If the layer already inherited a clipRect, we need to intersect with it before
+        // overriding the layer's clipRect and usesLayerClipping.
+        if (layer->usesLayerClipping())
             clipRect.intersect(layer->clipRect());
-            layer->setClipRect(clipRect);
-            layer->setUsesLayerClipping(true);
-        }
+
+        layer->setClipRect(clipRect);
+        layer->setUsesLayerClipping(true);
     }
 
     // Note that at this point, layer->drawTransform() is not necessarily the same as local variable drawTransform.
     // layerScreenSpaceTransform represents the transform between root layer's "screen space" and local layer space.
     TransformationMatrix layerScreenSpaceTransform = nextHierarchyMatrix;
     layerScreenSpaceTransform.multiply(layer->drawTransform());
     layerScreenSpaceTransform.translate3d(-0.5 * bounds.width(), -0.5 * bounds.height(), 0);
     layer->setScreenSpaceTransform(layerScreenSpaceTransform);
 
     // drawableContentRect() is always stored in the coordinate system of the
@@ skipping 176 matching lines @@
     walkLayersAndCalculateVisibleLayerRects<LayerChromium, Vector<RefPtr<LayerChromium> >, RenderSurfaceChromium>(renderSurfaceLayerList);
 }
 
 void CCLayerTreeHostCommon::calculateDrawTransformsAndVisibility(CCLayerImpl* layer, CCLayerImpl* rootLayer, const TransformationMatrix& parentMatrix, const TransformationMatrix& fullHierarchyMatrix, Vector<CCLayerImpl*>& renderSurfaceLayerList, Vector<CCLayerImpl*>& layerList, CCLayerSorter* layerSorter, int maxTextureSize)
 {
     calculateDrawTransformsAndVisibilityInternal<CCLayerImpl, Vector<CCLayerImpl*>, CCRenderSurface, CCLayerSorter>(layer, rootLayer, parentMatrix, fullHierarchyMatrix, 0, renderSurfaceLayerList, layerList, layerSorter, maxTextureSize);
     walkLayersAndCalculateVisibleLayerRects<CCLayerImpl, Vector<CCLayerImpl*>, CCRenderSurface>(renderSurfaceLayerList);
 }
 
 } // namespace WebCore