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

mojo/dart/test/bindings_generation_test.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.
 
 import 'dart:async';
 import 'dart:isolate';
 import 'dart:typed_data';
 import 'dart:mojo.bindings' as bindings;
 import 'dart:mojo.core' as core;
 
@@ skipping 95 matching lines @@
   Expect.listEquals(arrayValues.f3, arrayValues2.f3);
   Expect.listEquals(arrayValues.f4, arrayValues2.f4);
   Expect.listEquals(arrayValues.f5, arrayValues2.f5);
 }
 
 testSerializeStructs() {
   testSerializeNamedRegion();
   testSerializeArrayValueTypes();
 }
 
+void closingProviderIsolate(core.MojoMessagePipeEndpoint endpoint) {
+  var provider = new ProviderImpl(endpoint);
+  provider._stub.close();
+}
+
+Future<bool> runOnClosedTest() {
+  var testCompleter = new Completer();
+  var pipe = new core.MojoMessagePipe();
+  var proxy = new sample.ProviderProxy.fromEndpoint(pipe.endpoints[0]);
+  proxy.impl.onError = () => testCompleter.complete(true);
+  Isolate.spawn(closingProviderIsolate, pipe.endpoints[1]);
+  return testCompleter.future.then((b) {
+    Expect.isTrue(b);
+  });
+}
+
 main() async {
   testSerializeStructs();
   await testCallResponse();
   await testAwaitCallResponse();
+  await runOnClosedTest();
 }