Implement select listbox using shadow DOM

Source/core/rendering/RenderThemeChromiumMac.h

 /*
  * This file is part of the theme implementation for form controls in WebCore.
  *
  * Copyright (C) 2005 Apple Computer, Inc.
  * Copyright (C) 2008, 2009 Google, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 37 matching lines @@
 
     virtual Color platformActiveSelectionBackgroundColor() const OVERRIDE;
     virtual Color platformInactiveSelectionBackgroundColor() const OVERRIDE;
     virtual Color platformActiveSelectionForegroundColor() const OVERRIDE;
     virtual Color platformActiveListBoxSelectionBackgroundColor() const OVERRIDE;
     virtual Color platformActiveListBoxSelectionForegroundColor() const OVERRIDE;
     virtual Color platformInactiveListBoxSelectionBackgroundColor() const OVERRIDE;
     virtual Color platformInactiveListBoxSelectionForegroundColor() const OVERRIDE;
     virtual Color platformFocusRingColor() const OVERRIDE;
 
-    virtual ScrollbarControlSize scrollbarControlSizeForPart(ControlPart) OVERRIDE { return SmallScrollbar; }
+    virtual ScrollbarControlSize scrollbarControlSizeForPart(ControlPart part) OVERRIDE { return part == ListboxPart ? SmallScrollbar : RegularScrollbar; }
 
     virtual void platformColorsDidChange() OVERRIDE;
 
     // System fonts.
     virtual void systemFont(CSSValueID, FontDescription&) const OVERRIDE;
 
     virtual int minimumMenuListSize(RenderStyle*) const OVERRIDE;
 
     virtual void adjustSliderThumbSize(RenderStyle*, Element*) const OVERRIDE;
 
@@ skipping 138 matching lines @@
     mutable RetainPtr<NSTextFieldCell> m_textField;
 
     mutable HashMap<int, RGBA32> m_systemColorCache;
 
     RetainPtr<WebCoreRenderThemeNotificationObserver> m_notificationObserver;
 };
 
 } // namespace WebCore
 
 #endif // RenderThemeChromiumMac_h