Slimming Paint phase 2 compositing algorithm plumbing

Source/core/layout/LayoutView.h

Index: Source/core/layout/LayoutView.h
diff --git a/Source/core/layout/LayoutView.h b/Source/core/layout/LayoutView.h
index 672bcac0ee4045bcbe002fee5c71e78b71e0fea3..8b8e49ba85d42944f36979ff2ae61912f8e65de1 100644
--- a/Source/core/layout/LayoutView.h
+++ b/Source/core/layout/LayoutView.h
@@ -33,6 +33,7 @@
 #include "core/layout/PendingSelection.h"
 #include "platform/PODFreeListArena.h"
 #include "platform/RuntimeEnabledFeatures.h"
+#include "platform/graphics/paint/DisplayItemTransformTree.h"
 #include "platform/heap/Handle.h"
 #include "platform/scroll/ScrollableArea.h"
 #include "wtf/OwnPtr.h"
@@ -188,6 +189,9 @@ public:
     // It is very likely you do not want to call this method.
     void setShouldDoFullPaintInvalidationForViewAndAllDescendants();
 
+    void setTransformTree(PassOwnPtr<const DisplayItemTransformTree> transformTree) { m_transformTree = transformTree; }

[chrishtr, 2015/08/14 00:17:19]

Lets move this to WebViewImpl.

+    const DisplayItemTransformTree* transformTree() const { return m_transformTree.get(); }
+
 private:
     void mapLocalToContainer(const LayoutBoxModelObject* paintInvalidationContainer, TransformState&, MapCoordinatesFlags = ApplyContainerFlip, bool* wasFixed = nullptr, const PaintInvalidationState* = nullptr) const override;
 
@@ -233,6 +237,10 @@ private:
     OwnPtrWillBePersistent<HitTestCache> m_hitTestCache;
 
     OwnPtrWillBePersistent<PendingSelection> m_pendingSelection;
+
+    // TODO(pdr): This is only temporarily here and will be moving
+    // to RenderSurfaceLayerList in a followup patch.
+    OwnPtrWillBePersistent<const DisplayItemTransformTree> m_transformTree;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutView, isLayoutView());