Dart: Futures -> Callbacks.

mojo/dart/apptests/test_apps/pingpong/lib/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 'package:mojo/application.dart';
 import 'package:mojo/bindings.dart';
 import 'package:mojo/core.dart';
 
@@ skipping 29 matching lines @@
     assert(_pingPongClient == null);
     _pingPongClient = client;
   }
 
   void ping(int pingValue) {
     if (_pingPongClient != null) {
       _pingPongClient.pong(pingValue + 1);
     }
   }
 
-  Future pingTargetUrl(String url, int count,
-      [Function responseFactory]) async {
+  void pingTargetUrl(String url, int count, void callback(bool ok)) {
     if (_application == null) {
-      return responseFactory(false);
+      callback(false);
+      return;
     }
     var completer = new Completer();
     var pingPongService = new PingPongServiceInterfaceRequest();
     _application.connectToService(url, pingPongService);
 
     var pingPongClient = new PingPongClientImpl(count, completer);
     pingPongService.setClient(pingPongClient.client);
 
     for (var i = 0; i < count; i++) {
       pingPongService.ping(i);
     }
-    await completer.future;
-    await pingPongService.close();
-
-    return responseFactory(true);
+    completer.future.then((_) {
+      callback(true);
+      pingPongService.close();
+    });
   }
 
-  Future pingTargetService(PingPongServiceInterface service, int count,
-      [Function responseFactory]) async {
+  void pingTargetService(
+      PingPongServiceInterface service, int count, void callback(bool ok)) {
     var pingPongService = service;
     var completer = new Completer();
     var client = new PingPongClientImpl(count, completer);
     pingPongService.setClient(client.client);
 
     for (var i = 0; i < count; i++) {
       pingPongService.ping(i);
     }
-    await completer.future;
-    await pingPongService.close();
-
-    return responseFactory(true);
+    completer.future.then((_) {
+      callback(true);
+      pingPongService.close();
+    });
   }
 
   getPingPongService(PingPongServiceInterfaceRequest service) {
     var targetService = new PingPongServiceInterfaceRequest();
     _application.connectToService("mojo:dart_pingpong_target", targetService);
 
     // Pass along the interface request to another implementation of the
     // service.
     targetService.getPingPongService(service);
     targetService.close();
@@ skipping 31 matching lines @@
   }
 }
 
 main(List args, Object handleToken) {
   MojoHandle appHandle = new MojoHandle(handleToken);
   new PingPongApplication.fromHandle(appHandle)
     ..onError = ((_) {
       MojoHandle.reportLeakedHandles();
     });
 }