ash: Cleanup class/struct forward declarations

ash/test/lock_state_controller_test_api.h

 // 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.
 
 #ifndef ASH_TEST_LOCK_STATE_CONTROLLER_TEST_API_H_
 #define ASH_TEST_LOCK_STATE_CONTROLLER_TEST_API_H_
 
 #include <memory>
 
 #include "ash/wm/lock_state_controller.h"
 #include "base/timer/elapsed_timer.h"
 #include "base/timer/timer.h"
 
 namespace ash {
 
-namespace mojom {
-class ShutdownClient;
-}
-
 namespace test {
 
 // Helper class used by tests to access internal state.
 class LockStateControllerTestApi {
  public:
   explicit LockStateControllerTestApi(LockStateController* controller);
   ~LockStateControllerTestApi();
 
   void set_shutdown_controller(ShutdownController* shutdown_controller) {
     controller_->shutdown_controller_ = shutdown_controller;
@@ skipping 36 matching lines @@
  private:
   LockStateController* controller_;  // not owned
 
   DISALLOW_COPY_AND_ASSIGN(LockStateControllerTestApi);
 };
 
 }  // namespace test
 }  // namespace ash
 
 #endif  // ASH_TEST_LOCK_STATE_CONTROLLER_TEST_API_H_