Fix placement of overlay scrollbars on high DPI with box shadow.

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 227 matching lines @@
     // Paints the scrollbar part associated with the given graphics layer into the given context.
     void paintScrollableArea(const GraphicsLayer*, GraphicsContext&, const IntRect& interestRect) const;
     // Returns whether the given layer is part of the scrollable area, if any, associated with this mapping.
     bool isScrollableAreaLayer(const GraphicsLayer*) const;
 
     // Helper methods to updateGraphicsLayerGeometry:
     void computeGraphicsLayerParentLocation(const PaintLayer* compositingContainer, const IntRect& ancestorCompositingBounds, IntPoint& graphicsLayerParentLocation);
     void updateSquashingLayerGeometry(const IntPoint& graphicsLayerParentLocation, const PaintLayer* compositingContainer, Vector<GraphicsLayerPaintInfo>& layers, GraphicsLayer*, LayoutPoint* offsetFromTransformedAncestor, Vector<PaintLayer*>& layersNeedingPaintInvalidation);
     void updateMainGraphicsLayerGeometry(const IntRect& relativeCompositingBounds, const IntRect& localCompositingBounds, const IntPoint& graphicsLayerParentLocation);
     void updateAncestorClippingLayerGeometry(const PaintLayer* compositingContainer, const IntPoint& snappedOffsetFromCompositedAncestor, IntPoint& graphicsLayerParentLocation);
-    void updateOverflowControlsHostLayerGeometry(const PaintLayer* compositingStackingContext, const PaintLayer* compositingContainer);
+    void updateOverflowControlsHostLayerGeometry(const PaintLayer* compositingStackingContext, const PaintLayer* compositingContainer, IntPoint graphicsLayerParentLocation);
     void updateChildContainmentLayerGeometry(const IntRect& clippingBox, const IntRect& localCompositingBounds);
     void updateChildTransformLayerGeometry();
     void updateMaskLayerGeometry();
     void updateTransformGeometry(const IntPoint& snappedOffsetFromCompositedAncestor, const IntRect& relativeCompositingBounds);
     void updateForegroundLayerGeometry(const FloatSize& relativeCompositingBoundsSize, const IntRect& clippingBox);
     void updateBackgroundLayerGeometry(const FloatSize& relativeCompositingBoundsSize);
     void updateReflectionLayerGeometry(Vector<PaintLayer*>& layersNeedingPaintInvalidation);
     void updateScrollingLayerGeometry(const IntRect& localCompositingBounds);
     void updateChildClippingMaskLayerGeometry();
 
@@ skipping 209 matching lines @@
 
     // Keep track of whether the background is painted onto the scrolling contents layer for invalidations.
     unsigned m_backgroundPaintsOntoScrollingContentsLayer : 1;
 
     friend class CompositedLayerMappingTest;
 };
 
 } // namespace blink
 
 #endif // CompositedLayerMapping_h