Refactors keyboard related code so mash can use a keyboard

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 "ash/ash_export.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.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 scoped_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_