Refactor root element background painting

Source/core/layout/LayoutView.h

Index: Source/core/layout/LayoutView.h
diff --git a/Source/core/layout/LayoutView.h b/Source/core/layout/LayoutView.h
index 82fb7698f4085283687d89f2fd2e68f7ca1d4236..fa130a82c378c00a4d59c602c45dac674ea09630 100644
--- a/Source/core/layout/LayoutView.h
+++ b/Source/core/layout/LayoutView.h
@@ -173,6 +173,8 @@ public:
     void popLayoutState() { ASSERT(m_layoutState); m_layoutState = m_layoutState->next(); }
     virtual void invalidateTreeIfNeeded(PaintInvalidationState&) override final;
 
+    virtual LayoutRect visualOverflowRect() const override;
+
 private:
     virtual void mapLocalToContainer(const LayoutBoxModelObject* paintInvalidationContainer, TransformState&, MapCoordinatesFlags = ApplyContainerFlip, bool* wasFixed = 0, const PaintInvalidationState* = 0) const override;
     virtual const LayoutObject* pushMappingToContainer(const LayoutBoxModelObject* ancestorToStopAt, LayoutGeometryMap&) const override;
@@ -188,8 +190,6 @@ private:
 
     bool shouldUsePrintingLayout() const;
 
-    LayoutObject* backgroundLayoutObject() const;
-
     int viewLogicalWidthForBoxSizing() const;
     int viewLogicalHeightForBoxSizing() const;