Remove KeyboardUmaEventFilter

ash/keyboard_uma_event_filter.h

-// Copyright 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 ASH_KEYBOARD_UMA_EVENT_FILTER_H_
-#define ASH_KEYBOARD_UMA_EVENT_FILTER_H_
-
-#include "base/compiler_specific.h"
-#include "base/macros.h"
-#include "base/time/time.h"
-#include "ui/events/event_handler.h"
-
-namespace ash {
-
-// EventFilter for tracking keyboard-related metrics, which intercepts events
-// before they are processed by the usual path and logs metrics about the
-// events.
-class KeyboardUMAEventFilter : public ui::EventHandler {
- public:
-  KeyboardUMAEventFilter();
-  ~KeyboardUMAEventFilter() override;
-
-  // ui::EventHandler overrides:
-  void OnKeyEvent(ui::KeyEvent* event) override;
-
- private:
-  // The timestamp of the last character keystroke.
-  base::TimeTicks last_keystroke_time_;
-
-  DISALLOW_COPY_AND_ASSIGN(KeyboardUMAEventFilter);
-};
-
-}  // namespace ash
-
-#endif  // ASH_KEYBOARD_UMA_EVENT_FILTER_H_