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

Source/platform/graphics/paint/DisplayItemTransformTreeBuilder.h

Index: Source/platform/graphics/paint/DisplayItemTransformTreeBuilder.h
diff --git a/Source/platform/graphics/paint/DisplayItemTransformTreeBuilder.h b/Source/platform/graphics/paint/DisplayItemTransformTreeBuilder.h
index 70ca0bcbb9c37ee3279950c5030d711bdaa406df..4e5a137c4bdb7da100501ce8f3c1c4ace276a584 100644
--- a/Source/platform/graphics/paint/DisplayItemTransformTreeBuilder.h
+++ b/Source/platform/graphics/paint/DisplayItemTransformTreeBuilder.h
@@ -14,7 +14,10 @@
 namespace blink {
 
 class DisplayItem;
+class DisplayItemList;
 class DisplayItemTransformTree;
+class WebDisplayList;
+struct WebDisplayListDiff;
 
 class PLATFORM_EXPORT DisplayItemTransformTreeBuilder {
 public:
@@ -25,6 +28,8 @@ public:
     // This can be used to construct a WebDisplayItemTransformTree.
     PassOwnPtr<DisplayItemTransformTree> releaseTransformTree();
 
+    void build(const DisplayItemList& displayList, const WebDisplayListDiff&);
+
     // Process another display item from the list.
     void processDisplayItem(const DisplayItem&);