Change Widget subclasses to use a CullRect instead of an IntRect for painting.

third_party/WebKit/Source/core/frame/FrameView.h

 /*
    Copyright (C) 1997 Martin Jones (mjones@kde.org)
              (C) 1998 Waldo Bastian (bastian@kde.org)
              (C) 1998, 1999 Torben Weis (weis@kde.org)
              (C) 1999 Lars Knoll (knoll@kde.org)
              (C) 1999 Antti Koivisto (koivisto@kde.org)
    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
 
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
@@ skipping 496 matching lines @@
     IntPoint convertSelfToChild(const Widget* child, const IntPoint& point) const override
     {
         IntPoint newPoint = point;
         if (!isFrameViewScrollbar(child))
             newPoint = frameToContents(point);
         newPoint.moveBy(-child->location());
         return newPoint;
     }
 
     // Widget override. Handles painting of the contents of the view as well as the scrollbars.
-    void paint(GraphicsContext*, const IntRect&) const override;
-    void paint(GraphicsContext*, const GlobalPaintFlags, const IntRect&) const;
+    void paint(GraphicsContext*, const CullRect&) const override;
+    void paint(GraphicsContext*, const GlobalPaintFlags, const CullRect&) const;
     void paintContents(GraphicsContext*, const GlobalPaintFlags, const IntRect& damageRect) const;
 
     // Widget overrides to ensure that our children's visibility status is kept up to date when we get shown and hidden.
     void show() override;
     void hide() override;
     void setParentVisible(bool) override;
 
     bool isPointInScrollbarCorner(const IntPoint&);
     bool scrollbarCornerPresent() const;
     IntRect scrollCornerRect() const override;
@@ skipping 376 matching lines @@
     static const unsigned visualPixelThreshold = 32 * 32;
     if (m_visuallyNonEmptyPixelCount > visualPixelThreshold)
         setIsVisuallyNonEmpty();
 }
 
 DEFINE_TYPE_CASTS(FrameView, Widget, widget, widget->isFrameView(), widget.isFrameView());
 
 } // namespace blink
 
 #endif // FrameView_h