Fix crash on extension IME reloading on Linux Desktop with chromeos=1.

chromeos/dbus/ibus/mock_ibus_engine_service.cc

 // 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.
 
 #include "chromeos/dbus/ibus/mock_ibus_engine_service.h"
 
 namespace chromeos {
 
 MockIBusEngineService::MockIBusEngineService() {
 }
 
 MockIBusEngineService::~MockIBusEngineService() {
 }
 
 void MockIBusEngineService::SetEngine(IBusEngineHandlerInterface* handler) {
 }
 
-void MockIBusEngineService::UnsetEngine() {
+void MockIBusEngineService::UnsetEngine(IBusEngineHandlerInterface* handler) {
 }
 
 void MockIBusEngineService::RegisterProperties(
       const IBusPropertyList& property_list) {
 }
 
 void MockIBusEngineService::UpdatePreedit(const IBusText& ibus_text,
                                           uint32 cursor_pos,
                                           bool is_visible,
                                           IBusEnginePreeditFocusOutMode mode) {
@@ skipping 16 matching lines @@
                                             uint32 state) {
 }
 
 void MockIBusEngineService::RequireSurroundingText() {
 }
 
 void MockIBusEngineService::CommitText(const std::string& text) {
 }
 
 }  // namespace chromeos