cc : Determine if a layer is root by using the value in LayerTreeImpl

cc/layers/layer_impl.h

Index: cc/layers/layer_impl.h
diff --git a/cc/layers/layer_impl.h b/cc/layers/layer_impl.h
index f0044f56f2620c14214acd2437cff17aa01ba7be..6b6d6301c0a80b27b9f8e0d8d90a9105b6d6724a 100644
--- a/cc/layers/layer_impl.h
+++ b/cc/layers/layer_impl.h
@@ -109,8 +109,6 @@ class CC_EXPORT LayerImpl {
   scoped_ptr<LayerImpl> RemoveChild(LayerImpl* child);
   void SetParent(LayerImpl* parent);
 
-  bool HasAncestor(const LayerImpl* ancestor) const;
-
   void SetScrollParent(LayerImpl* parent);
 
   LayerImpl* scroll_parent() { return scroll_parent_; }