Calculate paint invalidation rect for scrollbars

third_party/WebKit/Source/core/layout/LayoutScrollbarPart.h

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 85 matching lines @@
     LayoutUnit paddingAfter() const override { return LayoutUnit(); }
     LayoutUnit paddingStart() const override { return LayoutUnit(); }
     LayoutUnit paddingEnd() const override { return LayoutUnit(); }
 
     void layoutHorizontalPart();
     void layoutVerticalPart();
 
     void computeScrollbarWidth();
     void computeScrollbarHeight();
 
+    void setNeedsPaintInvalidation();
+
     GC_PLUGIN_IGNORE("http://crbug.com/509911")
     LayoutScrollbar* m_scrollbar;
     ScrollbarPart m_part;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutScrollbarPart, isLayoutScrollbarPart());
 
 } // namespace blink
 
 #endif // LayoutScrollbarPart_h