Dart: Better handle leak checks. close() is async.

mojo/public/dart/src/application.dart

 // 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.
 
 part of application;
 
 class _ApplicationImpl implements application_mojom.Application {
   application_mojom.ApplicationStub _stub;
   shell_mojom.ShellProxy shell;
   Application _application;
@@ skipping 23 matching lines @@
   }
 
   @override
   void acceptConnection(String requestorUrl, ServiceProviderStub services,
       bindings.ProxyBase exposedServices, String resolvedUrl) => _application
       ._acceptConnection(requestorUrl, services, exposedServices, resolvedUrl);
 
   @override
   void requestQuit() => _application._requestQuitAndClose();
 
-  void close({bool nodefer: false}) {
+  Future close({bool nodefer: false}) {
     if (shell != null) shell.close();
-    _stub.close();
+    return _stub.close();
   }
 }
 
 // TODO(zra): Better documentation and examples.
 // To implement, do the following:
 // - Optionally override initialize() to process command-line args.
 // - Optionally override acceptConnection() if services are to be provided.
 // - Optionally override close() to clean up application resources.
 abstract class Application {
   _ApplicationImpl _applicationImpl;
   List<ApplicationConnection> _applicationConnections;
+  Function onError;
 
   Application(core.MojoMessagePipeEndpoint endpoint) {
     _applicationConnections = [];
     _applicationImpl = new _ApplicationImpl(this, endpoint);
-    _applicationImpl.onError = close;
+    _applicationImpl.onError = _errorHandler;
   }
 
   Application.fromHandle(core.MojoHandle appHandle) {
     _applicationConnections = [];
     _applicationImpl = new _ApplicationImpl.fromHandle(this, appHandle);
-    _applicationImpl.onError = close;
+    _applicationImpl.onError = _errorHandler;
   }
 
   void initialize(List<String> args, String url) {}
 
   // TODO(skydart): This is a temporary fix to allow sky application to consume
   // mojo services. Do not use for any other purpose.
   void initializeFromShellProxy(
           shell_mojom.ShellProxy shellProxy, List<String> args, String url) =>
       _applicationImpl.initialize(shellProxy, args, url);
 
@@ skipping 11 matching lines @@
     connectToApplication(url).requestService(proxy);
   }
 
   void requestQuit() {}
 
   void _requestQuitAndClose() {
     requestQuit();
     close();
   }
 
-  void close() {
+  void _errorHandler() {
+    close().then((_) {
+      if (onError != null) onError();
+    });
+  }
+
+  Future close() {
     assert(_applicationImpl != null);
     _applicationConnections.forEach((c) => c.close());
     _applicationConnections.clear();
-    _applicationImpl.close();
+    return _applicationImpl.close();
   }
 
   // This method closes all the application connections. Used during apptesting.
   void resetConnections() {
     assert(_applicationImpl != null);
     _applicationConnections.forEach((c) => c.close());
     _applicationConnections.clear();
   }
 
   void _acceptConnection(String requestorUrl, ServiceProviderStub services,
       ServiceProviderProxy exposedServices, String resolvedUrl) {
     var connection = new ApplicationConnection(services, exposedServices);
     _applicationConnections.add(connection);
     acceptConnection(requestorUrl, resolvedUrl, connection);
   }
 
   // Override this method to provide services on |connection|.
   void acceptConnection(String requestorUrl, String resolvedUrl,
       ApplicationConnection connection) {}
 }