Introduces a new scrollbar for message_center.

ui/views/controls/scroll_view.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_SCROLL_VIEW_H_
 #define UI_VIEWS_CONTROLS_SCROLL_VIEW_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
@@ skipping 52 matching lines @@
 
   // Customize the scrollbar design. ScrollView takes the ownership of the
   // specified ScrollBar. |horiz_sb| and |vert_sb| cannot be NULL.
   void SetHorizontalScrollBar(ScrollBar* horiz_sb);
   void SetVerticalScrollBar(ScrollBar* vert_sb);
 
   // View overrides:
   virtual void Layout() OVERRIDE;
   virtual bool OnKeyPressed(const ui::KeyEvent& event) OVERRIDE;
   virtual bool OnMouseWheel(const ui::MouseWheelEvent& e) OVERRIDE;
+  virtual void OnMouseEntered(const ui::MouseEvent& event) OVERRIDE;
+  virtual void OnMouseExited(const ui::MouseEvent& event) OVERRIDE;
   virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
   virtual const char* GetClassName() const OVERRIDE;
 
   // ScrollBarController overrides:
   virtual void ScrollToPosition(ScrollBar* source, int position) OVERRIDE;
   virtual int GetScrollIncrement(ScrollBar* source,
                                  bool is_page,
                                  bool is_positive) OVERRIDE;
 
  private:
@@ skipping 115 matching lines @@
  private:
   int top_margin_;
   int row_height_;
 
   DISALLOW_COPY_AND_ASSIGN(FixedRowHeightScrollHelper);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_SCROLL_VIEW_H_