Simplify VirtualKeyboardTray

ui/keyboard/keyboard_controller.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 UI_KEYBOARD_KEYBOARD_CONTROLLER_H_
 #define UI_KEYBOARD_KEYBOARD_CONTROLLER_H_
 
 #include <memory>
 
 #include "base/event_types.h"
@@ skipping 64 matching lines @@
   // Hides virtual keyboard and notifies observer bounds change.
   // This function should be called with a delay to avoid layout flicker
   // when the focus of input field quickly change. |automatic| is true when the
   // call is made by the system rather than initiated by the user.
   void HideKeyboard(HideReason reason);
 
   // Notifies the keyboard observer for keyboard bounds changed.
   void NotifyKeyboardBoundsChanging(const gfx::Rect& new_bounds);
 
   // Management of the observer list.
-  virtual void AddObserver(KeyboardControllerObserver* observer);
-  virtual void RemoveObserver(KeyboardControllerObserver* observer);
+  void AddObserver(KeyboardControllerObserver* observer);
+  void RemoveObserver(KeyboardControllerObserver* observer);
+  bool HasObserver(KeyboardControllerObserver* observer) const;
 
   KeyboardUI* ui() { return ui_.get(); }
 
   void set_lock_keyboard(bool lock) { lock_keyboard_ = lock; }
 
   KeyboardMode keyboard_mode() const { return keyboard_mode_; }
 
   void SetKeyboardMode(KeyboardMode mode);
 
   // Force the keyboard to show up if not showing and lock the keyboard if
@@ skipping 73 matching lines @@
   static KeyboardController* instance_;
 
   base::WeakPtrFactory<KeyboardController> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(KeyboardController);
 };
 
 }  // namespace keyboard
 
 #endif  // UI_KEYBOARD_KEYBOARD_CONTROLLER_H_