chrome: Cleanup class/struct forward declarations

chrome/browser/ui/ash/chrome_keyboard_ui.h

 // Copyright (c) 2013 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_ASH_CHROME_KEYBOARD_UI_H_
 #define CHROME_BROWSER_UI_ASH_CHROME_KEYBOARD_UI_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "ui/keyboard/content/keyboard_ui_content.h"
 
 namespace content {
 class BrowserContext;
 class WebContents;
 }
-namespace extensions {
-class ExtensionFunctionDispatcher;
-class WindowController;
-}
-namespace gfx {
-class Rect;
-}
 namespace keyboard {
 class KeyboardController;
 class KeyboardControllerObserver;
 }
 namespace ui {
 class InputMethod;
 }
 
 // Subclass of KeyboardUIContent. It is used by KeyboardController to get
 // access to the virtual keyboard window and setup Chrome extension functions.
@@ skipping 28 matching lines @@
 
   // content::WebContentsObserver overrides
   void RenderViewCreated(content::RenderViewHost* render_view_host) override;
 
   std::unique_ptr<keyboard::KeyboardControllerObserver> observer_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeKeyboardUI);
 };
 
 #endif  // CHROME_BROWSER_UI_ASH_CHROME_KEYBOARD_UI_H_