Get rid of one-off code in ScrollingCoordinator to handle graphics layer offsets.

Source/core/rendering/RenderLayer.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
@@ skipping 323 matching lines @@
     RenderLayer* scrollParent() const
     {
         return const_cast<RenderLayer*>(compositingInputs().scrollParent);
     }
 
     // Computes the position of the given render object in the space of |paintInvalidationContainer|.
     // FIXME: invert the logic to have paint invalidation containers take care of painting objects into them, rather than the reverse.
     // This will allow us to clean up this static method messiness.
     static LayoutPoint positionFromPaintInvalidationContainer(const RenderObject*, const RenderLayerModelObject* paintInvalidationContainer);
 
+    static void mapRectToPaintBackingCoordinates(const RenderLayerModelObject* paintInvalidationContainer, LayoutRect&);
+
     // Adjusts the given rect (in the coordinate space of the RenderObject) to the coordinate space of |paintInvalidationContainer|'s GraphicsLayer backing.
     static void mapRectToPaintInvalidationBacking(const RenderObject*, const RenderLayerModelObject* paintInvalidationContainer, LayoutRect&);
 
     // Computes the bounding paint invalidation rect for |renderObject|, in the coordinate space of |paintInvalidationContainer|'s GraphicsLayer backing.
     static LayoutRect computePaintInvalidationRect(const RenderObject*, const RenderLayer* paintInvalidationContainer);
 
     bool paintsWithTransparency(PaintBehavior paintBehavior) const
     {
         return isTransparent() && ((paintBehavior & PaintBehaviorFlattenCompositingLayers) || compositingState() != PaintsIntoOwnBacking);
     }
@@ skipping 71 matching lines @@
         // instead.
         RenderLayerModelObject* layerRenderer = renderer();
         return isRootLayer() || layerRenderer->isPositioned() || hasTransform();
     }
 
     // paintLayer() assumes that the caller will clip to the bounds of the painting dirty if necessary.
     void paintLayer(GraphicsContext*, const LayerPaintingInfo&, PaintLayerFlags);
 
     RenderLayerBlendInfo& blendInfo() { return m_blendInfo; }
 
-    void setOffsetFromSquashingLayerOrigin(IntSize offset) { m_offsetFromSquashingLayerOrigin = offset; }
-    IntSize offsetFromSquashingLayerOrigin() const { ASSERT(isAllowedToQueryCompositingState()); return m_offsetFromSquashingLayerOrigin; }
-
     bool scrollsOverflow() const;
 
     CompositingReasons potentialCompositingReasonsFromStyle() const { return m_potentialCompositingReasonsFromStyle; }
     void setPotentialCompositingReasonsFromStyle(CompositingReasons reasons) { ASSERT(reasons == (reasons & CompositingReasonComboAllStyleDeterminedReasons)); m_potentialCompositingReasonsFromStyle = reasons; }
 
     bool hasStyleDeterminedDirectCompositingReasons() const { return m_potentialCompositingReasonsFromStyle & CompositingReasonComboAllDirectStyleDeterminedReasons; }
 
     class CompositingInputs {
     public:
         CompositingInputs()
@@ skipping 253 matching lines @@
     // Pointer to the enclosing RenderLayer that caused us to be paginated. It is 0 if we are not paginated.
     RenderLayer* m_enclosingPaginationLayer;
 
     // These compositing reasons are updated whenever style changes, not while updating compositing layers.
     // They should not be used to infer the compositing state of this layer.
     CompositingReasons m_potentialCompositingReasonsFromStyle;
 
     // Once computed, indicates all that a layer needs to become composited using the CompositingReasons enum bitfield.
     CompositingReasons m_compositingReasons;
 
-    // Used for invalidating this layer's contents on the squashing GraphicsLayer.
-    IntSize m_offsetFromSquashingLayerOrigin;
-
     CompositingInputs m_compositingInputs;
 
     IntRect m_blockSelectionGapsBounds;
 
     OwnPtr<CompositedLayerMapping> m_compositedLayerMapping;
     OwnPtr<RenderLayerScrollableArea> m_scrollableArea;
 
     CompositedLayerMapping* m_groupedMapping;
 
     RenderLayerRepainter m_repainter;
     RenderLayerClipper m_clipper; // FIXME: Lazily allocate?
     OwnPtr<RenderLayerStackingNode> m_stackingNode;
     OwnPtr<RenderLayerReflectionInfo> m_reflectionInfo;
     RenderLayerBlendInfo m_blendInfo;
 
     LayoutSize m_subpixelAccumulation; // The accumulated subpixel offset of a composited layer's composited bounds compared to absolute coordinates.
 };
 
 } // namespace WebCore
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showLayerTree(const WebCore::RenderLayer*);
 void showLayerTree(const WebCore::RenderObject*);
 #endif
 
 #endif // RenderLayer_h