chrome: Cleanup class/struct forward declarations

chrome/browser/ui/cocoa/task_manager_mac.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 CHROME_BROWSER_UI_COCOA_TASK_MANAGER_MAC_H_
 #define CHROME_BROWSER_UI_COCOA_TASK_MANAGER_MAC_H_
 
 #import <Cocoa/Cocoa.h>
 
 #include <vector>
 
 #include "base/mac/scoped_nsobject.h"
 #include "base/macros.h"
 #include "chrome/browser/ui/task_manager/task_manager_table_model.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "ui/base/models/table_model_observer.h"
 
 @class WindowSizeAutosaver;
 
-namespace gfx {
-class ImageSkia;
-}
-
 namespace task_manager {
 class TaskManagerMac;
 }
 
 // This class is responsible for loading the task manager window and for
 // managing it.
 @interface TaskManagerWindowController
     : NSWindowController<NSTableViewDataSource,
                          NSTableViewDelegate,
                          NSMenuDelegate> {
@@ skipping 108 matching lines @@
   // An open task manager window. There can only be one open at a time. This
   // is reset to be null when the window is closed.
   static TaskManagerMac* instance_;
 
   DISALLOW_COPY_AND_ASSIGN(TaskManagerMac);
 };
 
 }  // namespace task_manager
 
 #endif  // CHROME_BROWSER_UI_COCOA_TASK_MANAGER_MAC_H_