chromeos: Convert D-Bus client classes' callback arguments to const reference

chromeos/dbus/mock_power_manager_client.h

 // Copyright (c) 2012 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 CHROMEOS_DBUS_MOCK_POWER_MANAGER_CLIENT_H_
 #define CHROMEOS_DBUS_MOCK_POWER_MANAGER_CLIENT_H_
 
 #include <string>
 
 #include "chromeos/dbus/power_manager_client.h"
@@ skipping 13 matching lines @@
   MOCK_METHOD0(IncreaseScreenBrightness, void(void));
   MOCK_METHOD2(SetScreenBrightnessPercent, void(double, bool));
   MOCK_METHOD1(GetScreenBrightnessPercent,
                void(const GetScreenBrightnessPercentCallback&));
   MOCK_METHOD1(RequestStatusUpdate, void(UpdateRequestType));
   MOCK_METHOD0(RequestRestart, void(void));
   MOCK_METHOD0(RequestShutdown, void(void));
   MOCK_METHOD1(CalculateIdleTime, void(const CalculateIdleTimeCallback&));
   MOCK_METHOD1(RequestIdleNotification, void(int64));
   MOCK_METHOD0(RequestActiveNotification, void(void));
-  MOCK_METHOD4(RequestPowerStateOverrides, void(uint32,
-                                                uint32,
-                                                int,
-                                                PowerStateRequestIdCallback));
+  MOCK_METHOD4(RequestPowerStateOverrides,
+               void(uint32,
+                    uint32,
+                    int,
+                    const PowerStateRequestIdCallback&));
   MOCK_METHOD0(NotifyScreenLockRequested, void(void));
   MOCK_METHOD0(NotifyScreenLockCompleted, void(void));
   MOCK_METHOD0(NotifyScreenUnlockRequested, void(void));
   MOCK_METHOD0(NotifyScreenUnlockCompleted, void(void));
 };
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_DBUS_MOCK_POWER_MANAGER_CLIENT_H_