chrome: dbus: support asynchronous method replies

dbus/bus.h

 // Copyright (c) 2011 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.
 
 #ifndef DBUS_BUS_H_
 #define DBUS_BUS_H_
 #pragma once
 
 #include <map>
 #include <set>
@@ skipping 82 matching lines @@
 //     if (!response)
 //       return;
 //   }
 //
 //   ...
 //   object_proxy.CallMethod(&method_call, timeout_ms,
 //                           base::Bind(&OnResponse));
 //
 // 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,
 //                   const std::string& object_path,
 //                   bool success) {
 //     // success is true if the method was exported successfully.
 //   }
 //
 //   ...
 //   dbus::ExportedObject* exported_object =
@@ skipping 357 matching lines @@
   // OnAddTimeout()/OnRemoveTimeou() are balanced.
   int num_pending_watches_;
   int num_pending_timeouts_;
 
   DISALLOW_COPY_AND_ASSIGN(Bus);
 };
 
 }  // namespace dbus
 
 #endif  // DBUS_BUS_H_