It is time.

ui/views/controls/scrollbar/native_scroll_bar.h

-// Copyright (c) 2012 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_SCROLLBAR_NATIVE_SCROLL_BAR_H_
-#define UI_VIEWS_CONTROLS_SCROLLBAR_NATIVE_SCROLL_BAR_H_
-
-#include <string>
-
-#include "base/compiler_specific.h"
-#include "base/gtest_prod_util.h"
-#include "ui/views/controls/scrollbar/scroll_bar.h"
-#include "ui/views/view.h"
-
-namespace ui {
-class NativeTheme;
-}
-
-namespace views {
-
-class NativeScrollBarWrapper;
-
-// The NativeScrollBar class is a scrollbar that uses platform's
-// native control.
-class VIEWS_EXPORT NativeScrollBar : public ScrollBar {
- public:
-  // The scroll-bar's class name.
-  static const char kViewClassName[];
-
-  // Create new scrollbar, either horizontal or vertical.
-  explicit NativeScrollBar(bool is_horiz);
-  virtual ~NativeScrollBar();
-
-  // Return the system sizes.
-  static int GetHorizontalScrollBarHeight(const ui::NativeTheme* theme);
-  static int GetVerticalScrollBarWidth(const ui::NativeTheme* theme);
-
- private:
-  friend class NativeScrollBarTest;
-  FRIEND_TEST_ALL_PREFIXES(NativeScrollBarTest, Scrolling);
-
-  // Overridden from View.
-  virtual gfx::Size GetPreferredSize() const override;
-  virtual void Layout() override;
-  virtual void ViewHierarchyChanged(
-      const ViewHierarchyChangedDetails& details) override;
-  virtual const char* GetClassName() const override;
-
-  // Overrideen from View for keyboard UI purpose.
-  virtual bool OnKeyPressed(const ui::KeyEvent& event) override;
-  virtual bool OnMouseWheel(const ui::MouseWheelEvent& e) override;
-
-  // Overridden from ui::EventHandler.
-  virtual void OnGestureEvent(ui::GestureEvent* event) override;
-
-  // Overridden from ScrollBar.
-  virtual void Update(int viewport_size,
-                      int content_size,
-                      int current_pos) override;
-  virtual int GetPosition() const override;
-  virtual int GetLayoutSize() const override;
-
-  // init border
-  NativeScrollBarWrapper* native_wrapper_;
-
-  DISALLOW_COPY_AND_ASSIGN(NativeScrollBar);
-};
-
-}  // namespace views
-
-#endif  // UI_VIEWS_CONTROLS_SCROLLBAR_NATIVE_SCROLL_BAR_H_