chrome: Cleanup class/struct forward declarations

chrome/browser/chromeos/input_method/candidate_window_controller_impl.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_CHROMEOS_INPUT_METHOD_CANDIDATE_WINDOW_CONTROLLER_IMPL_H_
 #define CHROME_BROWSER_CHROMEOS_INPUT_METHOD_CANDIDATE_WINDOW_CONTROLLER_IMPL_H_
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 12 matching lines @@
 }  // namespace ime
 }  // namespace ui
 
 namespace views {
 class Widget;
 }  // namespace views
 
 namespace chromeos {
 namespace input_method {
 
-class DelayableWidget;
 class ModeIndicatorController;
 
 // The implementation of CandidateWindowController.
 // CandidateWindowController controls the CandidateWindow.
 class CandidateWindowControllerImpl
     : public CandidateWindowController,
       public ui::ime::CandidateWindowView::Observer,
       public views::WidgetObserver,
       public IMECandidateWindowHandlerInterface {
  public:
@@ skipping 48 matching lines @@
 
   base::ObserverList<CandidateWindowController::Observer> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(CandidateWindowControllerImpl);
 };
 
 #endif  // CHROME_BROWSER_CHROMEOS_INPUT_METHOD_CANDIDATE_WINDOW_CONTROLLER_IMPL_H_
 
 }  // namespace input_method
 }  // namespace chromeos