ash: Cleanup class/struct forward declarations

ash/common/system/chromeos/network/network_icon.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_NETWORK_ICON_H_
 #define ASH_COMMON_SYSTEM_CHROMEOS_NETWORK_NETWORK_ICON_H_
 
 #include <string>
 
 #include "ash/ash_export.h"
 #include "base/strings/string16.h"
 #include "ui/gfx/image/image_skia.h"
 
 namespace chromeos {
 class NetworkState;
 }
 
 namespace ash {
 namespace network_icon {
 
-class AnimationObserver;
-
 // Type of icon which dictates color theme and VPN badging
 enum IconType {
   ICON_TYPE_TRAY,          // light icons with VPN badges
   ICON_TYPE_DEFAULT_VIEW,  // dark icons with VPN badges
   ICON_TYPE_LIST,          // dark icons without VPN badges
 };
 
 // Gets the image for the network associated with |service_path|. |network| must
 // not be NULL. |icon_type| determines the color theme and whether or not to
 // show the VPN badge. This caches badged icons per network per |icon_type|.
@@ skipping 35 matching lines @@
 
 // Called when the list of networks changes. Retreives the list of networks
 // from the global NetworkStateHandler instance and removes cached entries
 // that are no longer in the list.
 ASH_EXPORT void PurgeNetworkIconCache();
 
 }  // namespace network_icon
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_CHROMEOS_NETWORK_NETWORK_ICON_H_