Implement interfaces in PaintInfo and make it a class.

Source/core/rendering/RenderBox.h

Index: Source/core/rendering/RenderBox.h
diff --git a/Source/core/rendering/RenderBox.h b/Source/core/rendering/RenderBox.h
index 105f91fcf4c777edee12753ea951d6ffebca64bc..7e15491cdac625906fd19cc77f3445cae2415892 100644
--- a/Source/core/rendering/RenderBox.h
+++ b/Source/core/rendering/RenderBox.h
@@ -32,7 +32,7 @@ namespace WebCore {
 
 class RenderBoxRegionInfo;
 class RenderRegion;
-struct PaintInfo;
+class PaintInfo;
 
 enum SizeType { MainOrPreferredSize, MinSize, MaxSize };
 enum AvailableLogicalHeightType { ExcludeMarginBorderPadding, IncludeMarginBorderPadding };
@@ -593,12 +593,12 @@ protected:
     virtual bool foregroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect, unsigned maxDepthToTest) const;
     virtual bool computeBackgroundIsKnownToBeObscured() OVERRIDE;
 
-    void paintBackground(const PaintInfo&, const LayoutRect&, BackgroundBleedAvoidance = BackgroundBleedNone);
+    void paintBackground(PaintInfo&, const LayoutRect&, BackgroundBleedAvoidance = BackgroundBleedNone);
 
-    void paintFillLayer(const PaintInfo&, const Color&, const FillLayer*, const LayoutRect&, BackgroundBleedAvoidance, CompositeOperator, RenderObject* backgroundObject);
-    void paintFillLayers(const PaintInfo&, const Color&, const FillLayer*, const LayoutRect&, BackgroundBleedAvoidance = BackgroundBleedNone, CompositeOperator = CompositeSourceOver, RenderObject* backgroundObject = 0);
+    void paintFillLayer(PaintInfo&, const Color&, const FillLayer*, const LayoutRect&, BackgroundBleedAvoidance, CompositeOperator, RenderObject* backgroundObject);
+    void paintFillLayers(PaintInfo&, const Color&, const FillLayer*, const LayoutRect&, BackgroundBleedAvoidance = BackgroundBleedNone, CompositeOperator = CompositeSourceOver, RenderObject* backgroundObject = 0);
 
-    void paintMaskImages(const PaintInfo&, const LayoutRect&);
+    void paintMaskImages(PaintInfo&, const LayoutRect&);
 
     BackgroundBleedAvoidance determineBackgroundBleedAvoidance(GraphicsContext*) const;
     bool backgroundHasOpaqueTopLayer() const;
@@ -613,7 +613,7 @@ protected:
     virtual void mapLocalToContainer(const RenderLayerModelObject* repaintContainer, TransformState&, MapCoordinatesFlags = ApplyContainerFlip, bool* wasFixed = 0) const OVERRIDE;
     virtual void mapAbsoluteToLocalPoint(MapCoordinatesFlags, TransformState&) const;
 
-    void paintRootBoxFillLayers(const PaintInfo&);
+    void paintRootBoxFillLayers(PaintInfo&);
 
     RenderObject* splitAnonymousBoxesAroundChild(RenderObject* beforeChild);