Dart: Futures -> Callbacks.

examples/dart/wget/lib/main.dart

 #!mojo mojo:dart_content_handler
 // 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.
 
 // Run with, e.g.:
 // mojo_shell "mojo:dart_wget http://www.google.com"
 
 import 'dart:async';
 import 'dart:typed_data';
 
 import 'package:mojo/application.dart';
 import 'package:mojo/core.dart';
 import 'package:mojo/mojo/url_request.mojom.dart';
+import 'package:mojo/mojo/url_response.mojom.dart';
 import 'package:mojo_services/mojo/network_service.mojom.dart';
 import 'package:mojo_services/mojo/url_loader.mojom.dart';
 
 class WGet extends Application {
   NetworkServiceInterfaceRequest _networkService;
   UrlLoaderProxy _urlLoader;
 
   WGet.fromHandle(MojoHandle handle) : super.fromHandle(handle);
 
   void initialize(List<String> args, String url) {
@@ skipping 15 matching lines @@
     MojoHandle.reportLeakedHandles();
   }
 
   Future<ByteData> _getUrl(String url) async {
     _initInterfacesIfNeeded();
 
     var urlRequest = new UrlRequest()
       ..url = url
       ..autoFollowRedirects = true;
 
-    var urlResponse = await _urlLoader.start(urlRequest);
+    var c = new Completer();
+    _urlLoader.start(urlRequest, (UrlResponse response) {
+      c.complete(response);
+    });
+    var urlResponse = await _urlLoader.responseOrError(c.future);
     print(">>> Headers <<<");
-    print(urlResponse.response.headers.join('\n'));
+    print(urlResponse.headers.join('\n'));
 
-    return DataPipeDrainer.drainHandle(urlResponse.response.body);
+    return DataPipeDrainer.drainHandle(urlResponse.body);
   }
 
   void _initInterfacesIfNeeded() {
     if (_networkService == null) {
       _networkService = new NetworkServiceInterfaceRequest();
       connectToService("mojo:network_service", _networkService);
     }
     if (_urlLoader == null) {
       _urlLoader = new UrlLoaderInterfaceRequest();
       _networkService.createUrlLoader(_urlLoader);
     }
   }
 
   void _closeInterfaces() {
     _urlLoader.close();
     _urlLoader = null;
     _networkService.close();
     _networkService = null;
   }
 }
 
 main(List args, handleToken) {
   MojoHandle appHandle = new MojoHandle(handleToken);
   new WGet.fromHandle(appHandle);
 }