Adding a Views scrollbar implementation.

views/controls/scrollbar/native_scroll_bar_views.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 VIEWS_CONTROLS_SCROLLBAR_NATIVE_SCROLL_BAR_VIEWS_H_
+#define VIEWS_CONTROLS_SCROLLBAR_NATIVE_SCROLL_BAR_VIEWS_H_
+#pragma once
+
+#include "ui/gfx/native_theme.h"
+#include "ui/gfx/point.h"
+#include "views/controls/button/button.h"
+#include "views/controls/scrollbar/native_scroll_bar_wrapper.h"
+#include "views/view.h"
+
+namespace gfx {
+class Canvas;
+}
+
+namespace views {
+
+class ScrollBarContainer;
+class ScrollBarThumb;
+
+// Views implementation for the scrollbar.
+class NativeScrollBarViews : public View,
+                             public ButtonListener,
+                             public NativeScrollBarWrapper {
+ public:
+  // Creates new scrollbar, either horizontal or vertical.
+  explicit NativeScrollBarViews(NativeScrollBar* native_scroll_bar);
+  virtual ~NativeScrollBarViews();
+
+ private:
+  // Overridden from View for layout purpose.
+  virtual void Layout();
+  virtual gfx::Size GetPreferredSize();
+
+  // Overridden from View for keyboard UI purpose.
+  virtual bool OnKeyPressed(const KeyEvent& event) OVERRIDE;
+  virtual bool OnMousePressed(const MouseEvent& event) OVERRIDE;
+  virtual void OnMouseEntered(const MouseEvent& event) OVERRIDE;
+  virtual void OnMouseExited(const MouseEvent& event) OVERRIDE;
+  virtual bool OnMouseWheel(const MouseWheelEvent& e) OVERRIDE;
+  virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
+
+  // BaseButton::ButtonListener overrides:
+  virtual void ButtonPressed(Button* sender,
+                             const views::Event& event) OVERRIDE;
+
+  // Overridden from NativeScrollBarWrapper.
+  virtual int GetPosition() const;
+  virtual View* GetView();
+  virtual void Update(int viewport_size, int content_size, int current_pos);
+
+  // Moves the scrollbar by the given value. Negative value is allowed.
+  // (moves upward)
+  void MoveBy(int o);

[Ben Goodger (Google), 2011/08/19 17:44:33]

What is the unit. Pixels or something else?

+
+  // Moves the scrollbar by the page (viewport) size.
+  void MovePage(bool positive);

[Ben Goodger (Google), 2011/08/19 17:44:33]

I would prefer if this expressed direction up or down.

MoveByPage.

+
+  // Moves the scrollbar by predefined step size.
+  void MoveStep(bool positive);

[Ben Goodger (Google), 2011/08/19 17:44:33]

MoveByStep.

+
+  // Moves the scrollbar to the given position. MoveTo(0) moves it to the top.
+  void MoveTo(int p);
+
+  // Moves the scrollbar to the end.
+  void MoveToBottom();

[Ben Goodger (Google), 2011/08/19 17:44:33]

Prefer start/end terminology to top/bottom left/right, since scrollbars can have
different orientations.

+
+  // Invoked when the scrollbar's position is changed.
+  void ValueChanged();
+
+  // Returns the area for the track. This is the area of the scrollbar minus
+  // the size of the arrow buttons.
+  gfx::Rect GetTrackBounds() const;
+
+  // The NativeScrollBar we are bound to.
+  NativeScrollBar* native_scroll_bar_;
+
+  // The scroll bar buttons (Up/Down, Left/Right).
+  Button* prev_button_;
+  Button* next_button_;
+
+  ScrollBarThumb* thumb_;
+
+  gfx::NativeTheme::ExtraParams params_;
+  gfx::NativeTheme::Part part_;
+  gfx::NativeTheme::State state_;
+
+  DISALLOW_COPY_AND_ASSIGN(NativeScrollBarViews);
+};
+
+}  // namespace views
+
+#endif  // #ifndef VIEWS_CONTROLS_SCROLLBAR_NATIVE_SCROLL_BAR_VIEWS_H_
+