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

mojo/public/dart/src/application_connection.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;
 
 typedef Object ServiceFactory(core.MojoMessagePipeEndpoint endpoint);
 typedef void FallbackServiceFactory(
     String interfaceName, core.MojoMessagePipeEndpoint endpoint);
 
 class LocalServiceProvider implements ServiceProvider {
   final ApplicationConnection connection;
   ServiceProviderStub _stub;
 
   LocalServiceProvider(this.connection, this._stub) {
     assert(_stub.isOpen);
     _stub.impl = this;
   }
 
   set onError(Function f) {
     _stub.onError = f;
   }
 
-  void close({bool nodefer: false}) => _stub.close(nodefer: nodefer);
+  Future close({bool nodefer: false}) => _stub.close(nodefer: nodefer);
 
   void connectToService(
       String interfaceName, core.MojoMessagePipeEndpoint pipe) {
     if (connection._nameToServiceFactory.containsKey(interfaceName)) {
       connection._nameToServiceFactory[interfaceName](pipe);
       return;
     }
     if (connection.fallbackServiceFactory != null) {
       connection.fallbackServiceFactory(interfaceName, pipe);
       return;
@@ skipping 54 matching lines @@
     remoteServiceProvider.ptr.connectToService(proxy.name, pipe.endpoints[1]);
     return proxy;
   }
 
   void provideService(String interfaceName, ServiceFactory factory) {
     assert(_localServiceProvider != null);
     _nameToServiceFactory[interfaceName] = factory;
   }
 
   void _errorHandler() {
-    if (onError != null) onError();
-    close();
+    close().then((_) {
+      if (onError != null) onError();
+    });
   }
 
-  void close({bool nodefer: false}) {
+  Future close({bool nodefer: false}) {
+    var rspCloseFuture;
+    var lspCloseFuture;
     if (remoteServiceProvider != null) {
-      remoteServiceProvider.close();
+      rspCloseFuture = remoteServiceProvider.close();
       remoteServiceProvider = null;
+    } else {
+      rspCloseFuture = new Future.value(null);
     }
     if (_localServiceProvider != null) {
-      _localServiceProvider.close(nodefer: nodefer);
+      lspCloseFuture = _localServiceProvider.close(nodefer: nodefer);
       _localServiceProvider = null;
+    } else {
+      lspCloseFuture = new Future.value(null);
     }
+    return rspCloseFuture.then((_) => lspCloseFuture);
   }
 }