Move overdraw tracking code from GraphicsContext to CanvasRenderingContext2D

Source/core/html/canvas/CanvasRenderingContext2D.h

 /*
  * Copyright (C) 2006, 2007, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 257 matching lines @@
         // Text state.
         TextAlign m_textAlign;
         TextBaseline m_textBaseline;
         Direction m_direction;
 
         String m_unparsedFont;
         Font m_font;
         bool m_realizedFont;
 
         bool m_hasClip;
+        bool m_hasComplexClip;
 
         ClipList m_clipList;
     };
 
     CanvasRenderingContext2D(HTMLCanvasElement*, const CanvasContextCreationAttributes& attrs, Document&);
 
     State& modifiableState() { ASSERT(!state().m_unrealizedSaveCount); return *m_stateStack.last(); }
     const State& state() const { return *m_stateStack.last(); }
 
     void applyLineDash() const;
@@ skipping 42 matching lines @@
     void fullCanvasCompositedDraw(PassOwnPtr<Closure> draw);
 
     void drawFocusIfNeededInternal(const Path&, Element*);
     bool focusRingCallIsValid(const Path&, Element*);
     void drawFocusRing(const Path&);
 
     bool hasClip() { return state().m_hasClip; }
 
     void validateStateStack();
 
+    enum DrawType {
+        NormalFill,
+        ClipFill, // Normal fill that is already known to cover the current clip
+        UntransformedUnclippedFill
+    };
+
+    enum ImageType {
+        NoImage,
+        OpaqueImage,
+        NonOpaqueImage
+    };
+
+    void checkOverdraw(const SkRect&, const SkPaint*, ImageType, DrawType);
+
     virtual bool is2d() const override { return true; }
     virtual bool isAccelerated() const override;
     virtual bool hasAlpha() const override { return m_hasAlpha; }
     virtual void setIsHidden(bool) override;
 
     virtual bool isTransformInvertible() const override { return state().m_invertibleCTM; }
 
     virtual WebLayer* platformLayer() const override;
     TextDirection toTextDirection(Direction, RenderStyle** computedStyle = nullptr) const;
 
@@ skipping 10 matching lines @@
     Timer<CanvasRenderingContext2D> m_dispatchContextLostEventTimer;
     Timer<CanvasRenderingContext2D> m_dispatchContextRestoredEventTimer;
     Timer<CanvasRenderingContext2D> m_tryRestoreContextEventTimer;
 };
 
 DEFINE_TYPE_CASTS(CanvasRenderingContext2D, CanvasRenderingContext, context, context->is2d(), context.is2d());
 
 } // namespace blink
 
 #endif // CanvasRenderingContext2D_h