Libcros changes for issue_12743: Add async RequestUpdateCheck call.

chromeos_update_engine.h

 // Copyright (c) 2010 The Chromium OS 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 CHROMEOS_UPDATE_ENGINE_H_
 #define CHROMEOS_UPDATE_ENGINE_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 46 matching lines @@
 // Register an UpdateMonitor callback.
 extern UpdateStatusConnection (*MonitorUpdateStatus)(UpdateMonitor monitor,
                                                      void*);
 // Unregister an UpdateMonitor callback.
 extern void (*DisconnectUpdateProgress)(UpdateStatusConnection connection);
 
 // Poll for the status once. Returns true on success.
 extern bool (*RetrieveUpdateProgress)(UpdateProgress* information);
 // Tell UpdateEngine daemon to check for an update. Returns true on success.
 extern bool (*InitiateUpdateCheck)();
+// Asynchronously tell UpdateEngine daemon to check for an update.
+// If |callback| is non NULL, call with the result when the request completes.
+enum UpdateResult {
+  UPDATE_RESULT_SUCCESS,
+  UPDATE_RESULT_FAILED,
+  UPDATE_RESULT_DBUS_FAILED
+};
+typedef void (*UpdateCallback)(void* user_data,
+                               UpdateResult result,
+                               const char* error_msg);
+extern void (*RequestUpdateCheck)(UpdateCallback callback, void* user_data);
 // Tell UpdateEngine daemon to reboot the system if an update has been
 // downloaded and installed. Returns true on success.
 extern bool (*RebootIfUpdated)();
 // Set the release track (channel). |track| should look like
 // "beta-channel" and "dev-channel". Returns true on success.
 extern bool (*SetTrack)(const std::string& track);
 // Return the release track (channel). On error, return an empty string.
 extern std::string (*GetTrack)();
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_UPDATE_ENGINE_H_