ash: Use SessionController instead of SessionStateDelegate

ash/common/shelf/shelf_locking_manager.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_COMMON_SHELF_SHELF_LOCKING_MANAGER_H_
 #define ASH_COMMON_SHELF_SHELF_LOCKING_MANAGER_H_
 
 #include "ash/ash_export.h"
 #include "ash/common/session/session_state_observer.h"
 #include "ash/common/shell_observer.h"
@@ skipping 24 matching lines @@
   // LockStateObserver:
   void OnLockStateEvent(EventType event) override;
 
  private:
   // Update the shelf state for session and screen lock changes.
   void UpdateLockedState();
 
   WmShelf* shelf_;
   bool session_locked_ = false;
   bool screen_locked_ = false;
-  ShelfAlignment stored_alignment_ = SHELF_ALIGNMENT_BOTTOM;
+  ShelfAlignment stored_alignment_;
 
   DISALLOW_COPY_AND_ASSIGN(ShelfLockingManager);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SHELF_SHELF_LOCKING_MANAGER_H_