Mojo: Make overriding OnConnectionError optional

mojo/services/view_manager/view_manager_connection.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_VIEW_MANAGER_CONNECTION_H_
 #define MOJO_SERVICES_VIEW_MANAGER_VIEW_MANAGER_CONNECTION_H_
 
 #include <set>
 #include <vector>
 
@@ skipping 22 matching lines @@
 
 // Manages a connection from the client.
 class MOJO_VIEW_MANAGER_EXPORT ViewManagerConnection
     : public InterfaceImpl<IViewManager>,
       public NodeDelegate {
  public:
   ViewManagerConnection(RootNodeManager* root_node_manager);
   virtual ~ViewManagerConnection();
 
   virtual void OnConnectionEstablished() MOJO_OVERRIDE;
-  virtual void OnConnectionError() MOJO_OVERRIDE;
 
   TransportConnectionId id() const { return id_; }
 
   // Returns the Node with the specified id.
   Node* GetNode(const NodeId& id) {
     return const_cast<Node*>(
         const_cast<const ViewManagerConnection*>(this)->GetNode(id));
   }
   const Node* GetNode(const NodeId& id) const;
 
@@ skipping 104 matching lines @@
 
 #if defined(OS_WIN)
 #pragma warning(pop)
 #endif
 
 }  // namespace service
 }  // namespace view_manager
 }  // namespace mojo
 
 #endif  // MOJO_SERVICES_VIEW_MANAGER_VIEW_MANAGER_CONNECTION_H_