First step at synchronizing client model changes with service.

mojo/services/public/cpp/view_manager/view_tree_node.h

 // Copyright 2014 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 MOJO_SERVICES_PUBLIC_CPP_VIEW_MANAGER_VIEW_TREE_NODE_H_
 #define MOJO_SERVICES_PUBLIC_CPP_VIEW_MANAGER_VIEW_TREE_NODE_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/observer_list.h"
 
 namespace mojo {
 namespace services {
 namespace view_manager {
 
+class ViewManager;
 class ViewTreeNodeObserver;
 
 class ViewTreeNode {
  public:
   typedef std::vector<ViewTreeNode*> Children;
 
-  ViewTreeNode();
+  explicit ViewTreeNode(ViewManager* manager);
+  ViewTreeNode();  // Used for tests.
   ~ViewTreeNode();
 
   // Configuration.
+  uint16_t id() const { return id_; }
   void set_owned_by_parent(bool owned_by_parent) {
     owned_by_parent_ = owned_by_parent;
   }
 
   // Observation.
   void AddObserver(ViewTreeNodeObserver* observer);
   void RemoveObserver(ViewTreeNodeObserver* observer);
 
   // Tree.
   ViewTreeNode* parent() { return parent_; }
   const ViewTreeNode* parent() const { return parent_; }
   const Children& children() const { return children_; }
 
   void AddChild(ViewTreeNode* child);
   void RemoveChild(ViewTreeNode* child);
 
   bool Contains(ViewTreeNode* child) const;
 
  private:
   friend class ViewTreeNodePrivate;
 
+  ViewManager* manager_;
+  uint16_t id_;
   bool owned_by_parent_;
   ViewTreeNode* parent_;
   Children children_;
 
   ObserverList<ViewTreeNodeObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(ViewTreeNode);
 };
 
 }  // namespace view_manager
 }  // namespace services
 }  // namespace mojo
 
 #endif  // MOJO_SERVICES_PUBLIC_CPP_VIEW_MANAGER_VIEW_TREE_NODE_H_