Dart: Renames dart:mojo_blah -> mojo:blah

services/dart/test/pingpong/main.dart

 // Copyright 2015 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.
 
 import 'dart:async';
-import 'dart:mojo_application';
-import 'dart:mojo_bindings';
-import 'dart:mojo_core';
+import 'mojo:application';
+import 'mojo:bindings';
+import 'mojo:core';
 
 import 'package:services/dart/test/pingpong_service.mojom.dart';
 
 class PingPongClientImpl extends PingPongClient {
   Completer _completer;
   int _count;
 
   PingPongClientImpl.unbound(this._count, this._completer) : super.unbound() {
     super.delegate = this;
   }
@@ skipping 94 matching lines @@
     connection.listen();
   }
 }
 
 main(List args) {
   MojoHandle appHandle = new MojoHandle(args[0]);
   String url = args[1];
   var pingPongApplication = new PingPongApplication.fromHandle(appHandle);
   pingPongApplication.listen();
 }