Remove name for not exported service.

mojo/services/native_viewport/interfaces/native_viewport_event_dispatcher.mojom

 // Copyright 2016 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.
 
 [DartPackage="mojo_services"]
 module mojo;
 
 import "input_events/interfaces/input_events.mojom";
 
-[ServiceName="mojo::NativeViewportEventDispatcher"]
 interface NativeViewportEventDispatcher {
   OnEvent(Event event) => ();
 };