Dart: Adds optional named arguments for creating bindings.

services/dart/test/pingpong_target/main.dart

Index: services/dart/test/pingpong_target/main.dart
diff --git a/services/dart/test/pingpong_target/main.dart b/services/dart/test/pingpong_target/main.dart
index 5500322d69dab55ef456eeb011f1a7f801a38c12..15a6b19667466cb0e5a46f8936605e4022be208e 100644
--- a/services/dart/test/pingpong_target/main.dart
+++ b/services/dart/test/pingpong_target/main.dart
@@ -16,9 +16,8 @@ class PingPongServiceImpl implements PingPongService {
 
   PingPongServiceImpl(Application application, MojoMessagePipeEndpoint endpoint)
       : _application = application {
-    _stub = new PingPongServiceStub.fromEndpoint(endpoint)
-            ..delegate = this
-            ..listen();
+    _stub = new PingPongServiceStub.fromEndpoint(
+        endpoint, impl: this);
   }
 
   void setClient(ProxyBase proxyBase) {
@@ -34,19 +33,19 @@ class PingPongServiceImpl implements PingPongService {
       _pingPongClient = null;
     }
     _stub.close();
-    if (_application != null) {
-      _application.close();
-    }
   }
 }
 
 class PingPongApplication extends Application {
   PingPongApplication.fromHandle(MojoHandle handle) : super.fromHandle(handle);
 
-  void acceptConnection(String requestorUrl, ApplicationConnection connection) {
+  void acceptConnection(String requestorUrl,
+                        ApplicationConnection connection,
+                        String resolvedUrl) {
     connection.provideService(PingPongServiceName,
         (endpoint) => new PingPongServiceImpl(this, endpoint));
-    connection.listen();
+    // Close the application when the first connection goes down.
+    connection.listen(onClosed: close);
   }
 }