Slimming Paint phase 2 compositing algorithm plumbing & skeleton display list API.

Source/platform/graphics/ContentLayerDelegate.h

 /*
  * Copyright (C) 2012 Google 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 18 matching lines @@
 #include "platform/geometry/IntSize.h"
 #include "public/platform/WebContentLayerClient.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/PassOwnPtr.h"
 
 class SkCanvas;
 
 namespace blink {
 
 class DisplayItemList;
+class DisplayItemTransformTree;
+class DisplayList;
 class GraphicsContext;
 class IntRect;
 
 class PLATFORM_EXPORT GraphicsContextPainter {
 public:
     virtual void paint(GraphicsContext&, const IntRect& clip) = 0;
     virtual DisplayItemList* displayItemList() = 0;
 
+    virtual const DisplayList* displayList() const { return 0; }
+    virtual const DisplayItemTransformTree* transformTree() const { return 0; }
+
 protected:
     virtual ~GraphicsContextPainter() { }
 };
 
 class PLATFORM_EXPORT ContentLayerDelegate : public WebContentLayerClient {
     WTF_MAKE_NONCOPYABLE(ContentLayerDelegate);
 
 public:
     explicit ContentLayerDelegate(GraphicsContextPainter*);
     ~ContentLayerDelegate() override;
 
     // WebContentLayerClient implementation.
     void paintContents(SkCanvas*, const WebRect& clip, WebContentLayerClient::PaintingControlSetting = PaintDefaultBehavior) override;
     void paintContents(WebDisplayItemList*, const WebRect& clip, WebContentLayerClient::PaintingControlSetting = PaintDefaultBehavior) override;
     size_t approximateUnsharedMemoryUsage() const override;
 
+    const WebDisplayList* displayList() const override;
+
+    // This is only set on a root graphics layer. Alternatively, this could be set on the layer tree host.
+    const WebDisplayItemTransformTree* transformTree() const override;
+
 private:
     GraphicsContextPainter* m_painter;
 };
 
 } // namespace blink
 
 #endif // ContentLayerDelegate_h