Remove last MD reference from TrayPopupUtils.

ui/views/controls/non_md_slider.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 UI_VIEWS_CONTROLS_NON_MD_SLIDER_H_
-#define UI_VIEWS_CONTROLS_NON_MD_SLIDER_H_
-
-#include "base/macros.h"
-#include "ui/views/controls/slider.h"
-#include "ui/views/view.h"
-#include "ui/views/views_export.h"
-
-namespace views {
-class Slider;
-
-class VIEWS_EXPORT NonMdSlider : public Slider {
- public:
-  explicit NonMdSlider(SliderListener* listener);
-  ~NonMdSlider() override;
-
-  // ui::Slider:
-  void UpdateState(bool control_on) override;
-
-  // views::View:
-  void OnPaint(gfx::Canvas* canvas) override;
-  const char* GetClassName() const override;
-
- protected:
-  // ui::Slider:
-  int GetThumbWidth() override;
-
- private:
-  void UpdateSliderAppearance(bool control_on);
-
-  // Array used to hold active slider states and disabled slider states images.
-  const int* bar_active_images_;
-  const int* bar_disabled_images_;
-  const gfx::ImageSkia* thumb_;
-
-  // Array used to hold current state of slider images.
-  const gfx::ImageSkia* images_[4];
-  int bar_height_;
-
-  DISALLOW_COPY_AND_ASSIGN(NonMdSlider);
-};
-
-}  // namespace views
-
-#endif  // UI_VIEWS_CONTROLS_NON_MD_SLIDER_H_