Makes it so a node can only the root of one connection at a time

mojo/services/view_manager/root_node_manager.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_VIEW_MANAGER_ROOT_NODE_MANAGER_H_
 #define MOJO_SERVICES_VIEW_MANAGER_ROOT_NODE_MANAGER_H_
 
 #include <map>
 #include <set>
 
@@ skipping 51 matching lines @@
     // Marks the connection with the specified id as having seen a message.
     void MarkConnectionAsMessaged(ConnectionSpecificId connection_id) {
       message_ids_.insert(connection_id);
     }
 
     // Returns true if MarkConnectionAsMessaged(connection_id) was invoked.
     bool DidMessageConnection(ConnectionSpecificId connection_id) const {
       return message_ids_.count(connection_id) > 0;
     }
 
+    // Sends OnServerChangeIdAdvanced() to all connections that have not yet
+    // been messaged.
+    void SendServerChangeIdAdvanced();
+
    private:
     RootNodeManager* root_;
     const ConnectionSpecificId connection_id_;
     const ChangeType change_type_;
     const bool is_delete_node_;
 
     // See description of MarkConnectionAsMessaged/DidMessageConnection.
     std::set<ConnectionSpecificId> message_ids_;
 
     DISALLOW_COPY_AND_ASSIGN(ScopedChange);
@@ skipping 44 matching lines @@
   // to avoid sending ServerChangeIdAdvanced() unnecessarily.
   void OnConnectionMessagedClient(ConnectionSpecificId id);
 
   // Returns true if OnConnectionMessagedClient() was invoked for id.
   bool DidConnectionMessageClient(ConnectionSpecificId id) const;
 
   ViewManagerServiceImpl* GetConnectionByCreator(
       ConnectionSpecificId creator_id,
       const std::string& url) const;
 
+  // Returns the ViewManagerServiceImpl that has |id| as a root.
+  ViewManagerServiceImpl* GetConnectionWithRoot(const NodeId& id);
+
   void DispatchViewInputEventToWindowManager(const View* view,
                                              const ui::Event* event);
 
   // These functions trivially delegate to all ViewManagerServiceImpls, which in
   // term notify their clients.
   void ProcessNodeDestroyed(Node* node);
   void ProcessNodeBoundsChanged(const Node* node,
                                 const gfx::Rect& old_bounds,
                                 const gfx::Rect& new_bounds);
   void ProcessNodeHierarchyChanged(const Node* node,
@@ skipping 25 matching lines @@
   // by FinishChange() once the change is done.
   //
   // Changes should never nest, meaning each PrepareForChange() must be
   // balanced with a call to FinishChange() with no PrepareForChange()
   // in between.
   void PrepareForChange(ScopedChange* change);
 
   // Balances a call to PrepareForChange().
   void FinishChange();
 
+  // See description in ScopedChange.
+  void SendServerChangeIdAdvanced();
+
   // Returns true if the specified connection originated the current change.
   bool IsChangeSource(ConnectionSpecificId connection_id) const {
     return current_change_ && current_change_->connection_id() == connection_id;
   }
 
   // Implementation of the two embed variants.
   ViewManagerServiceImpl* EmbedImpl(ConnectionSpecificId creator_id,
                                     const String& url,
                                     const NodeId& root_id);
 
@@ skipping 37 matching lines @@
   ScopedChange* current_change_;
 
   DISALLOW_COPY_AND_ASSIGN(RootNodeManager);
 };
 
 }  // namespace service
 }  // namespace view_manager
 }  // namespace mojo
 
 #endif  // MOJO_SERVICES_VIEW_MANAGER_ROOT_NODE_MANAGER_H_