Change PaintLayer::m_layoutObject to a reference.

third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h

 /*
  * Copyright (C) 2009, 2010, 2011 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 358 matching lines @@
   void createPrimaryGraphicsLayer();
   void destroyGraphicsLayers();
 
   std::unique_ptr<GraphicsLayer> createGraphicsLayer(
       CompositingReasons,
       SquashingDisallowedReasons = SquashingDisallowedReasonsNone);
   bool toggleScrollbarLayerIfNeeded(std::unique_ptr<GraphicsLayer>&,
                                     bool needsLayer,
                                     CompositingReasons);
 
-  LayoutBoxModelObject* layoutObject() const {
+  LayoutBoxModelObject& layoutObject() const {
     return m_owningLayer.layoutObject();
   }
   PaintLayerCompositor* compositor() const {
     return m_owningLayer.compositor();
   }
 
   void updateInternalHierarchy();
   void updatePaintingPhases();
   bool updateClippingLayers(bool needsAncestorClip, bool needsDescendantClip);
   bool updateClippingLayers(bool needsAncestorClip,
@@ skipping 92 matching lines @@
       const PaintLayer& referenceLayer,
       const GraphicsLayerPaintInfo&,
       const Vector<GraphicsLayerPaintInfo>& layers);
 
   // Conservatively check that a border-radius clip does not clip a child.
   // This is a fast approximate test. Depending on the shape of the child and
   // the size of the border radius, this method may return false when in fact
   // the child is not clipped. We accept the approximation because most border
   // radii are small and the outcome is used to reduce the number of layers,
   // not influence correctness.
-  bool ancestorRoundedCornersWontClip(const LayoutObject* child,
-                                      const LayoutObject* clippingAncestor);
+  bool ancestorRoundedCornersWontClip(
+      const LayoutBoxModelObject& child,
+      const LayoutBoxModelObject& clippingAncestor);
 
   // Return true in |owningLayerIsClipped| iff |m_owningLayer|'s compositing
   // ancestor is not a descendant (inclusive) of the clipping container for
   // |m_owningLayer|. Return true in |owningLayerIsMasked| iff
   // |owningLayerIsClipped| is true and |m_owningLayer|'s compositing ancestor
   // is not a descendant (inclusive) of a container that applies a mask for
   // |m_owningLayer|.
   void owningLayerClippedOrMaskedByLayerNotAboveCompositedAncestor(
       const PaintLayer* scrollParent,
       bool& owningLayerIsClipped,
@@ skipping 197 matching lines @@
   unsigned m_backgroundPaintsOntoGraphicsLayer : 1;
 
   bool m_drawsBackgroundOntoContentLayer;
 
   friend class CompositedLayerMappingTest;
 };
 
 }  // namespace blink
 
 #endif  // CompositedLayerMapping_h