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

public/platform/WebLayer.h

Index: public/platform/WebLayer.h
diff --git a/public/platform/WebLayer.h b/public/platform/WebLayer.h
index 60bd11970b22a112cea48c9db6b028b0745a1db0..c533863806add0277428080c4d2232aeb9798009 100644
--- a/public/platform/WebLayer.h
+++ b/public/platform/WebLayer.h
@@ -30,6 +30,8 @@
 #include "WebColor.h"
 #include "WebCommon.h"
 #include "WebCompositorAnimation.h"
+#include "WebDisplayItemTransformTree.h"
+#include "WebDisplayList.h"
 #include "WebDoublePoint.h"
 #include "WebFloatPoint3D.h"
 #include "WebPoint.h"
@@ -231,6 +233,11 @@ public:
     virtual bool isOrphan() const = 0;
 
     virtual void setWebLayerClient(WebLayerClient*) = 0;
+
+    virtual const WebDisplayList* displayList() { return 0; };
+
+    // This is only set on a root graphics layer.
+    virtual const WebDisplayItemTransformTree* transformTree() { return 0; };
 };
 
 } // namespace blink