ash: Cleanup class/struct forward declarations

ash/common/system/tray/system_tray.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 ASH_COMMON_SYSTEM_TRAY_SYSTEM_TRAY_H_
 #define ASH_COMMON_SYSTEM_TRAY_SYSTEM_TRAY_H_
 
 #include <map>
 #include <memory>
 #include <vector>
@@ skipping 14 matching lines @@
 class SystemBubbleWrapper;
 class SystemTrayDelegate;
 class SystemTrayItem;
 class TrayAccessibility;
 class TrayAudio;
 class TrayCast;
 class TrayDate;
 class TraySystemInfo;
 class TrayTiles;
 class TrayUpdate;
-class TrayUser;
 class WebNotificationTray;
 
 // There are different methods for creating bubble views.
 enum BubbleCreationType {
   BUBBLE_CREATE_NEW,    // Closes any existing bubble and creates a new one.
   BUBBLE_USE_EXISTING,  // Uses any existing bubble, or creates a new one.
 };
 
 class ASH_EXPORT SystemTray : public TrayBackgroundView,
                               public views::TrayBubbleView::Delegate {
@@ skipping 236 matching lines @@
   std::unique_ptr<KeyEventWatcher> key_event_watcher_;
 
   std::unique_ptr<ActivationObserver> activation_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(SystemTray);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_TRAY_SYSTEM_TRAY_H_