ash: Cleanup class/struct forward declarations

ash/common/system/chromeos/network/tray_vpn.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_CHROMEOS_NETWORK_TRAY_VPN_H_
 #define ASH_COMMON_SYSTEM_CHROMEOS_NETWORK_TRAY_VPN_H_
 
 #include <memory>
 
 #include "ash/common/system/chromeos/network/tray_network_state_observer.h"
 #include "ash/common/system/tray/system_tray_item.h"
 #include "base/macros.h"
 
 namespace ash {
 class TrayNetworkStateObserver;
 
 namespace tray {
 class NetworkDetailedView;
 class VpnDefaultView;
-class VpnDetailedView;
 }
 
 class TrayVPN : public SystemTrayItem,
                 public TrayNetworkStateObserver::Delegate {
  public:
   explicit TrayVPN(SystemTray* system_tray);
   ~TrayVPN() override;
 
   // SystemTrayItem
   views::View* CreateTrayView(LoginStatus status) override;
@@ skipping 12 matching lines @@
   tray::VpnDefaultView* default_;
   tray::NetworkDetailedView* detailed_;
   std::unique_ptr<TrayNetworkStateObserver> network_state_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(TrayVPN);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_CHROMEOS_NETWORK_TRAY_VPN_H_