Mojo: Make overriding OnConnectionError optional

mojo/services/native_viewport/native_viewport_service.cc

 // Copyright 2013 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/native_viewport/native_viewport_service.h"
 
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "base/time/time.h"
 #include "mojo/public/cpp/bindings/allocation_scope.h"
@@ skipping 23 matching lines @@
   NativeViewportImpl(shell::Context* context)
       : context_(context),
         widget_(gfx::kNullAcceleratedWidget),
         waiting_for_event_ack_(false) {}
   virtual ~NativeViewportImpl() {
     // Destroy the NativeViewport early on as it may call us back during
     // destruction and we want to be in a known state.
     native_viewport_.reset();
   }
 
-  virtual void OnConnectionError() OVERRIDE {}
-
   virtual void Create(const Rect& bounds) OVERRIDE {
     native_viewport_ =
         services::NativeViewport::Create(context_, this);
     native_viewport_->Init(bounds);
     client()->OnCreated();
     OnBoundsChanged(bounds);
   }
 
   virtual void Show() OVERRIDE {
     native_viewport_->Show();
@@ skipping 132 matching lines @@
 
 
 MOJO_NATIVE_VIEWPORT_EXPORT mojo::Application*
     CreateNativeViewportService(mojo::shell::Context* context,
                                 mojo::ScopedMessagePipeHandle shell_handle) {
   mojo::Application* app = new mojo::Application(shell_handle.Pass());
   app->AddService<mojo::services::NativeViewportImpl>(context);
   return app;
 }