mash: Move tray accessibility and keyboard to //ash/common

ash/keyboard/keyboard_ui.h

-// Copyright 2016 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 ASH_KEYBOARD_KEYBOARD_UI_H_
-#define ASH_KEYBOARD_KEYBOARD_UI_H_
-
-#include <memory>
-
-#include "ash/ash_export.h"
-#include "base/macros.h"
-#include "base/observer_list.h"
-
-namespace ash {
-
-class KeyboardUIObserver;
-
-// KeyboardUI wraps the appropriate keyboard ui depending upon whether ash is
-// running in mus or non-mus.
-class ASH_EXPORT KeyboardUI {
- public:
-  virtual ~KeyboardUI();
-
-  static std::unique_ptr<KeyboardUI> Create();
-
-  virtual void Show() = 0;
-  virtual void Hide() = 0;
-
-  // Returns true if the keyboard is enabled.
-  virtual bool IsEnabled() = 0;
-
-  void AddObserver(KeyboardUIObserver* observer);
-  void RemoveObserver(KeyboardUIObserver* observer);
-
-  // Applist also queries this for bounds. If app list remains in ash then
-  // we need to plumb bounds through here too.
-
- protected:
-  KeyboardUI();
-
-  base::ObserverList<KeyboardUIObserver>* observers() { return &observers_; }
-
- private:
-  base::ObserverList<KeyboardUIObserver> observers_;
-};
-
-}  // namespace ash
-
-#endif  // ASH_KEYBOARD_KEYBOARD_UI_H_