ui: Cleanup class/struct forward declarations

ui/views/focus/focus_manager_delegate.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 UI_VIEWS_FOCUS_FOCUS_MANAGER_DELEGATE_H_
 #define UI_VIEWS_FOCUS_FOCUS_MANAGER_DELEGATE_H_
 
 #include "ui/views/views_export.h"
 
 namespace ui {
 class Accelerator;
-class AcceleratorTarget;
 }
 
 namespace views {
 
 // Delegate interface for views::FocusManager.
 class VIEWS_EXPORT FocusManagerDelegate {
  public:
   virtual ~FocusManagerDelegate() {}
 
   // Activate the target associated with the specified accelerator.
   // First, AcceleratorPressed handler of the most recently registered target
   // is called, and if that handler processes the event (i.e. returns true),
   // this method immediately returns. If not, we do the same thing on the next
   // target, and so on.
   // Returns true if an accelerator was activated.
   virtual bool ProcessAccelerator(const ui::Accelerator& accelerator) = 0;
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_FOCUS_FOCUS_MANAGER_DELEGATE_H_