Generalize paint chunks to clips, and implement clips in LayerPainter.

Source/core/paint/LayerPainter.h

Index: Source/core/paint/LayerPainter.h
diff --git a/Source/core/paint/LayerPainter.h b/Source/core/paint/LayerPainter.h
index 3d1369f218473b81b7ab68d64b839869a3731492..593cdd35d19c16e88e05fcf003eb209f4f294675 100644
--- a/Source/core/paint/LayerPainter.h
+++ b/Source/core/paint/LayerPainter.h
@@ -11,6 +11,7 @@
 namespace blink {
 
 class ClipRect;
+class PaintClipRecorder;
 struct PaintInfo;
 class LayoutPoint;
 class RenderLayer;
@@ -53,8 +54,8 @@ private:
 
     enum BorderRadiusClippingRule { IncludeSelfForBorderRadius, DoNotIncludeSelfForBorderRadius };
 
-    void clipToRect(const LayerPaintingInfo&, GraphicsContext*, const ClipRect&, PaintLayerFlags, BorderRadiusClippingRule = IncludeSelfForBorderRadius);
-    void restoreClip(GraphicsContext*, const LayoutRect& paintDirtyRect, const ClipRect&);
+    void clipToRect(const LayerPaintingInfo&, GraphicsContext*, const ClipRect&, PaintLayerFlags, PaintClipRecorder*, BorderRadiusClippingRule = IncludeSelfForBorderRadius);
+    void restoreClip(GraphicsContext*, const LayoutRect& paintDirtyRect, const ClipRect&, PaintClipRecorder*);
 
     // Returns whether this layer should be painted during sofware painting (i.e., not via calls from CompositedLayerMapping to draw into composited
     // layers).