Dart: Adds optional named arguments for creating bindings.

services/dart/test/pingpong_target/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 'mojo:application';
 import 'mojo:bindings';
 import 'mojo:core';
 
 import 'package:services/dart/test/pingpong_service.mojom.dart';
 
 class PingPongServiceImpl implements PingPongService {
   PingPongServiceStub _stub;
   Application _application;
   PingPongClientProxy _pingPongClient;
 
   PingPongServiceImpl(Application application, MojoMessagePipeEndpoint endpoint)
       : _application = application {
-    _stub = new PingPongServiceStub.fromEndpoint(endpoint)
-            ..delegate = this
-            ..listen();
+    _stub = new PingPongServiceStub.fromEndpoint(endpoint, impl: this);
   }
 
   void setClient(ProxyBase proxyBase) {
     assert(_pingPongClient == null);
     _pingPongClient = proxyBase;
   }
 
   void ping(int pingValue) => _pingPongClient.ptr.pong(pingValue + 1);
 
   void quit() {
     if (_pingPongClient != null) {
       _pingPongClient.close();
       _pingPongClient = null;
     }
     _stub.close();
-    if (_application != null) {
-      _application.close();
-    }
   }
 }
 
 class PingPongApplication extends Application {
   PingPongApplication.fromHandle(MojoHandle handle) : super.fromHandle(handle);
 
   @override
   void acceptConnection(String requestorUrl, String resolvedUrl,
-                        ApplicationConnection connection) {
-    connection.provideService(PingPongServiceName,
+      ApplicationConnection connection) {
+    connection.provideService(
+        PingPongServiceName,
         (endpoint) => new PingPongServiceImpl(this, endpoint));
-    connection.listen();
+    // Close the application when the first connection goes down.
+    connection.listen(onClosed: close);
   }
 }
 
 main(List args) {
   MojoHandle appHandle = new MojoHandle(args[0]);
   String url = args[1];
   new PingPongApplication.fromHandle(appHandle);
 }