Make ExportedObject and ObjectProxy own Bus as scoped_refptr.

dbus/exported_object.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_EXPORTED_OBJECT_H_
 #define DBUS_EXPORTED_OBJECT_H_
 #pragma once
 
 #include <string>
 #include <map>
@@ skipping 126 matching lines @@
 
   // Redirects the function call to HandleMessage().
   static DBusHandlerResult HandleMessageThunk(DBusConnection* connection,
                                               DBusMessage* raw_message,
                                               void* user_data);
 
   // Redirects the function call to OnUnregistered().
   static void OnUnregisteredThunk(DBusConnection* connection,
                                   void* user_data);
 
-  Bus* bus_;
+  scoped_refptr<Bus> bus_;
   std::string service_name_;
   std::string object_path_;
   bool object_is_registered_;
 
   // The method table where keys are absolute method names (i.e. interface
   // name + method name), and values are the corresponding callbacks.
   typedef std::map<std::string, MethodCallCallback> MethodTable;
   MethodTable method_table_;
 };
 
 }  // namespace dbus
 
 #endif  // DBUS_EXPORTED_OBJECT_H_