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

ash/keyboard/keyboard_ui_observer.h

Index: ash/keyboard/keyboard_ui_observer.h
diff --git a/ash/keyboard/keyboard_ui_observer.h b/ash/keyboard/keyboard_ui_observer.h
deleted file mode 100644
index c1b130b04c3a5eac04fb29a6eaa5d47f5efe26e6..0000000000000000000000000000000000000000
--- a/ash/keyboard/keyboard_ui_observer.h
+++ /dev/null
@@ -1,23 +0,0 @@
-// 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_OBSERVER_H_
-#define ASH_KEYBOARD_KEYBOARD_UI_OBSERVER_H_
-
-#include "ash/ash_export.h"
-#include "base/macros.h"
-
-namespace ash {
-
-class ASH_EXPORT KeyboardUIObserver {
- public:
-  virtual void OnKeyboardEnabledStateChanged(bool new_value) = 0;
-
- protected:
-  virtual ~KeyboardUIObserver() {}
-};
-
-}  // namespace ash
-
-#endif  // ASH_KEYBOARD_KEYBOARD_UI_OBSERVER_H_