Activate LayerImpl tree with sync+push instead of pointer swap

cc/tree_synchronizer.h

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_TREE_SYNCHRONIZER_H_
 #define CC_TREE_SYNCHRONIZER_H_
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "cc/cc_export.h"
 #include "cc/scoped_ptr_hash_map.h"
 
 namespace cc {
 
 class LayerImpl;
 class LayerTreeImpl;
 class Layer;
 
 class CC_EXPORT TreeSynchronizer {
 public:
     // Accepts a Layer tree and returns a reference to a LayerImpl tree that duplicates the structure
     // of the Layer tree, reusing the LayerImpls in the tree provided by oldLayerImplRoot if possible.
     static scoped_ptr<LayerImpl> synchronizeTrees(Layer* layerRoot, scoped_ptr<LayerImpl> oldLayerImplRoot, LayerTreeImpl*);
+    static scoped_ptr<LayerImpl> synchronizeTrees(LayerImpl* layerRoot, scoped_ptr<LayerImpl> oldLayerImplRoot, LayerTreeImpl*);
 
-    // Pushes properties from a Layer tree to a structurally equivalent
+    // Pushes properties from a Layer or LayerImpl tree to a structurally equivalent
     // LayerImpl tree.
     static void pushProperties(Layer* layerRoot, LayerImpl* layerImplRoot);
+    static void pushProperties(LayerImpl* layerRoot, LayerImpl* layerImplRoot);
 
 private:
     TreeSynchronizer(); // Not instantiable.
 
-    typedef ScopedPtrHashMap<int, LayerImpl> ScopedPtrLayerImplMap;
-    typedef base::hash_map<int, LayerImpl*> RawPtrLayerImplMap;
-
-    // Declared as static member functions so they can access functions on Layer as a friend class.
-    static scoped_ptr<LayerImpl> reuseOrCreateLayerImpl(RawPtrLayerImplMap& newLayers, ScopedPtrLayerImplMap& oldLayers, Layer*, LayerTreeImpl*);
-    static void collectExistingLayerImplRecursive(ScopedPtrLayerImplMap& oldLayers, scoped_ptr<LayerImpl>);
-    static scoped_ptr<LayerImpl> synchronizeTreeRecursive(RawPtrLayerImplMap& newLayers, ScopedPtrLayerImplMap& oldLayers, Layer*, LayerTreeImpl*);
-    static void updateScrollbarLayerPointersRecursive(const RawPtrLayerImplMap& newLayers, Layer*);
-
     DISALLOW_COPY_AND_ASSIGN(TreeSynchronizer);
 };
 
 } // namespace cc
 
 #endif  // CC_TREE_SYNCHRONIZER_H_