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

cc/layers/layer_impl.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_LAYERS_LAYER_IMPL_H_
 #define CC_LAYERS_LAYER_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 91 matching lines @@
   // Tree structure.
   LayerImpl* parent() { return parent_; }
   const LayerImpl* parent() const { return parent_; }
   const LayerImplList& children() const { return children_; }
   LayerImplList& children() { return children_; }
   LayerImpl* child_at(size_t index) const { return children_[index]; }
   void AddChild(scoped_ptr<LayerImpl> child);
   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_; }
   const LayerImpl* scroll_parent() const { return scroll_parent_; }
 
   void SetScrollChildren(std::set<LayerImpl*>* children);
 
   std::set<LayerImpl*>* scroll_children() { return scroll_children_.get(); }
   const std::set<LayerImpl*>* scroll_children() const {
     return scroll_children_.get();
@@ skipping 653 matching lines @@
   // If true, the layer or one of its descendants has a touch handler.
   bool layer_or_descendant_has_touch_handler_;
   bool sorted_for_recursion_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_LAYER_IMPL_H_