Dart: Reorganize files

services/dart/test/interfaces/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.
-
-[DartPackage="_mojo_for_test_only"]
-module test;
-
-[ServiceName="test::PingPongService"]
-interface PingPongService {
-  // Register the client interface with the service.
-  SetClient(PingPongClient client);
-
-  // 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.
-  PingTargetURL(string url, uint16 count) => (bool ok);
-
-  // Ping the PingPongService |count| times and return true
-  // after the final Pong() is received.
-  PingTargetService(PingPongService service, uint16 count) => (bool ok);
-
-  // Return a PingPongService
-  GetPingPongService(PingPongService& service);
-
-  // Make it stop.
-  Quit();
-};
-
-interface PingPongClient {
-  Pong(uint16 pong_value);
-};