Transfer LayerImpl ownership to LayerTreeImpl

cc/trees/tree_synchronizer.h

Index: cc/trees/tree_synchronizer.h
diff --git a/cc/trees/tree_synchronizer.h b/cc/trees/tree_synchronizer.h
index 3c873741ad0539b6116140861baee8dc319895c1..260bd7b455d81f7a3f719f66ab7f3446c76f8f6f 100644
--- a/cc/trees/tree_synchronizer.h
+++ b/cc/trees/tree_synchronizer.h
@@ -21,14 +21,9 @@ class CC_EXPORT TreeSynchronizer {
   // 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 old_layer_impl_root if possible.
-  static scoped_ptr<LayerImpl> SynchronizeTrees(
-      Layer* layer_root,
-      scoped_ptr<LayerImpl> old_layer_impl_root,
-      LayerTreeImpl* tree_impl);
-  static scoped_ptr<LayerImpl> SynchronizeTrees(
-      LayerImpl* layer_root,
-      scoped_ptr<LayerImpl> old_layer_impl_root,
-      LayerTreeImpl* tree_impl);
+  static void SynchronizeTrees(Layer* layer_root, LayerTreeImpl* tree_impl);
+  static void SynchronizeTrees(LayerImpl* layer_root, LayerTreeImpl* tree_impl);
+
   static void PushLayerProperties(LayerTreeImpl* pending_tree,
                                   LayerTreeImpl* active_tree);
   static void PushLayerProperties(LayerTreeHost* host_tree,