It is time.

ui/views/controls/scrollbar/base_scroll_bar_thumb.h

-// Copyright (c) 2011 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_BASE_SCROLL_BAR_THUMB_H_
-#define UI_VIEWS_CONTROLS_SCROLLBAR_BASE_SCROLL_BAR_THUMB_H_
-
-#include "ui/gfx/size.h"
-#include "ui/views/controls/button/custom_button.h"
-#include "ui/views/controls/scrollbar/scroll_bar.h"
-#include "ui/views/view.h"
-
-namespace gfx {
-class Canvas;
-}
-
-namespace views {
-
-class BaseScrollBar;
-
-///////////////////////////////////////////////////////////////////////////////
-//
-// BaseScrollBarThumb
-//
-//  A view that acts as the thumb in the scroll bar track that the user can
-//  drag to scroll the associated contents view within the viewport.
-//
-///////////////////////////////////////////////////////////////////////////////
-class VIEWS_EXPORT BaseScrollBarThumb : public View {
- public:
-  explicit BaseScrollBarThumb(BaseScrollBar* scroll_bar);
-  virtual ~BaseScrollBarThumb();
-
-  // Sets the size (width or height) of the thumb to the specified value.
-  void SetSize(int size);
-
-  // Retrieves the size (width or height) of the thumb.
-  int GetSize() const;
-
-  // Sets the position of the thumb on the x or y axis.
-  void SetPosition(int position);
-
-  // Gets the position of the thumb on the x or y axis.
-  int GetPosition() const;
-
-  // View overrides:
-  virtual gfx::Size GetPreferredSize() const override = 0;
-
- protected:
-  // View overrides:
-  virtual void OnPaint(gfx::Canvas* canvas) override = 0;
-  virtual void OnMouseEntered(const ui::MouseEvent& event) override;
-  virtual void OnMouseExited(const ui::MouseEvent& event) override;
-  virtual bool OnMousePressed(const ui::MouseEvent& event) override;
-  virtual bool OnMouseDragged(const ui::MouseEvent& event) override;
-  virtual void OnMouseReleased(const ui::MouseEvent& event) override;
-  virtual void OnMouseCaptureLost() override;
-
-  CustomButton::ButtonState GetState() const;
-  // Update our state and schedule a repaint when the mouse moves over us.
-  void SetState(CustomButton::ButtonState state);
-
-  BaseScrollBar* scroll_bar() { return scroll_bar_; }
-
- private:
-  // The BaseScrollBar that owns us.
-  BaseScrollBar* scroll_bar_;
-
-  int drag_start_position_;
-
-  // The position of the mouse on the scroll axis relative to the top of this
-  // View when the drag started.
-  int mouse_offset_;
-
-  // The current state of the thumb button.
-  CustomButton::ButtonState state_;
-
-  DISALLOW_COPY_AND_ASSIGN(BaseScrollBarThumb);
-};
-
-}  // namespace views
-
-#endif  // UI_VIEWS_CONTROLS_SCROLLBAR_BASE_SCROLL_BAR_THUMB_H_