chrome: dbus: support asynchronous method replies

dbus/bus.h

Index: dbus/bus.h
diff --git a/dbus/bus.h b/dbus/bus.h
index 89fba919fb35b279d7ef63551d26866db80b17eb..4af07ce1089fc2585a3c0eb6ff5dd040458e8600 100644
--- a/dbus/bus.h
+++ b/dbus/bus.h
@@ -100,11 +100,15 @@ class ObjectProxy;
 //
 // Exporting a method:
 //
-//   Response* Echo(dbus::MethodCall* method_call) {
+//   void Echo(dbus::MethodCall* method_call,
+//             dbus::ExportedObject::ResponseSender response_sender) {
 //     // Do something with method_call.
 //     Response* response = Response::FromMethodCall(method_call);
 //     // Build response here.
-//     return response;
+//     // Can send an immediate response here to implement a synchronous service
+//     // or store the response_sender and send a response later to implement an
+//     // asynchronous service.
+//     response_sender.Run(response);
 //   }
 //
 //   void OnExported(const std::string& interface_name,