Mojo: Make overriding OnConnectionError optional

mojo/services/view_manager/view_manager_connection.cc

 // 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.
 
 #include "mojo/services/view_manager/view_manager_connection.h"
 
 #include "base/stl_util.h"
 #include "mojo/public/cpp/bindings/allocation_scope.h"
 #include "mojo/services/view_manager/node.h"
 #include "mojo/services/view_manager/root_node_manager.h"
@@ skipping 52 matching lines @@
   root_node_manager_->AddConnection(this);
   std::vector<const Node*> to_send;
   GetUnknownNodesFrom(root_node_manager_->root(), &to_send);
   AllocationScope allocation_scope;
   client()->OnConnectionEstablished(
       id_,
       root_node_manager_->next_server_change_id(),
       Array<INode>::From(to_send));
 }
 
-void ViewManagerConnection::OnConnectionError() {}
-
 const Node* ViewManagerConnection::GetNode(const NodeId& id) const {
   if (id_ == id.connection_id) {
     NodeMap::const_iterator i = node_map_.find(id.node_id);
     return i == node_map_.end() ? NULL : i->second;
   }
   return root_node_manager_->GetNode(id);
 }
 
 View* ViewManagerConnection::GetView(const ViewId& id) {
   if (id_ == id.connection_id) {
@@ skipping 315 matching lines @@
 
 void ViewManagerConnection::OnNodeViewReplaced(const Node* node,
                                                const View* new_view,
                                                const View* old_view) {
   root_node_manager_->ProcessNodeViewReplaced(node, new_view, old_view);
 }
 
 }  // namespace service
 }  // namespace view_manager
 }  // namespace mojo