chromeos: Move device shutdown handling out of chrome into ash

ash/test/lock_state_controller_test_api.cc

 // Copyright 2016 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 "ash/test/lock_state_controller_test_api.h"
 
 #include <memory>
 #include <utility>
 
 #include "ash/public/interfaces/shutdown.mojom.h"
 
 namespace ash {
 namespace test {
 
 LockStateControllerTestApi::LockStateControllerTestApi(
     LockStateController* controller)
     : controller_(controller) {
   DCHECK(controller);
 }
 
 LockStateControllerTestApi::~LockStateControllerTestApi() {}
 
-void LockStateControllerTestApi::SetShutdownClient(
-    std::unique_ptr<mojom::ShutdownClient> client) {
-  controller_->shutdown_client_ = std::move(client);
-}
-
 }  // namespace test
 }  // namespace ash