Put code in //services/js in namespace js

services/js/test/pingpong_service.mojom

 // 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.
 
-module mojo;
+module js;
 
 [Client=PingPongClient]
 interface PingPongService {
   // Typically calls PingPongClient::Pong(ping_value + 1)
   Ping(uint16 ping_value);
 
   // Ping the PingPongService at |url| |count| times and return true
   // after the final Pong() is received.
   PingTarget(string url, uint16 count) => (bool ok);
 
   // Make it stop.
   Quit();
 };
 
 interface PingPongClient {
   Pong(uint16 pong_value);
 };