Put rare PaintLayer fields into PaintLayerRareData

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

Index: third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h
diff --git a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h
index e133f32587eb0859934b54f0e8ee9cf0a5206ab0..f15530d5c55d3eafbc9bc5e35f5ec4100e5c85e9 100644
--- a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h
+++ b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h
@@ -253,8 +253,8 @@ private:
     bool requiresVerticalScrollbarLayer() const { return m_owningLayer.scrollableArea() && m_owningLayer.scrollableArea()->verticalScrollbar(); }
     bool requiresScrollCornerLayer() const { return m_owningLayer.scrollableArea() && !m_owningLayer.scrollableArea()->scrollCornerAndResizerRect().isEmpty(); }
     bool updateScrollingLayers(bool scrollingLayers);
-    void updateScrollParent(PaintLayer*);
-    void updateClipParent(PaintLayer* scrollParent);
+    void updateScrollParent(const PaintLayer*);
+    void updateClipParent(const PaintLayer* scrollParent);
     bool updateSquashingLayers(bool needsSquashingLayers);
     void updateDrawsContent();
     void updateChildrenTransform();
@@ -306,9 +306,9 @@ private:
 
     // Return true if |m_owningLayer|'s compositing ancestor is not a descendant (inclusive) of the
     // clipping container for |m_owningLayer|.
-    bool owningLayerClippedByLayerNotAboveCompositedAncestor(PaintLayer* scrollParent);
+    bool owningLayerClippedByLayerNotAboveCompositedAncestor(const PaintLayer* scrollParent);
 
-    PaintLayer* scrollParent();
+    const PaintLayer* scrollParent();
 
     // Clear the groupedMapping entry on the layer at the given index, only if that layer does
     // not appear earlier in the set of layers for this object.