ui: Cleanup class/struct forward declarations

ui/keyboard/content/keyboard_ui_content.h

 // Copyright 2015 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_KEYBOARD_CONTENT_KEYBOARD_UI_CONTENT_H_
 #define UI_KEYBOARD_CONTENT_KEYBOARD_UI_CONTENT_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "content/public/common/media_stream_request.h"
 #include "ui/aura/window_observer.h"
 #include "ui/base/ime/text_input_type.h"
 #include "ui/keyboard/keyboard_export.h"
 #include "ui/keyboard/keyboard_ui.h"
 
 namespace aura {
 class Window;
 }
 namespace content {
 class BrowserContext;
-class SiteInstance;
 class WebContents;
 }
 namespace gfx {
 class Rect;
 }
-namespace ui {
-class InputMethod;
-}
 namespace wm {
 class Shadow;
 }
 
 namespace keyboard {
 
-class KeyboardController;
 class WindowBoundsChangeObserver;
 
 // An implementation of KeyboardUI that uses a content::WebContents to implement
 //the keyboard.
 class KEYBOARD_EXPORT KeyboardUIContent : public KeyboardUI,
                                           public aura::WindowObserver {
  public:
   class TestApi {
    public:
     explicit TestApi(KeyboardUIContent* ui) : ui_(ui) {}
@@ skipping 75 matching lines @@
   std::unique_ptr<wm::Shadow> shadow_;
 
   std::unique_ptr<WindowBoundsChangeObserver> window_bounds_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(KeyboardUIContent);
 };
 
 }  // namespace keyboard
 
 #endif  // UI_KEYBOARD_CONTENT_KEYBOARD_UI_CONTENT_H_