Remove mainthread overhang painting code

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 440 matching lines @@
     IntSize scrollOffset() const { return toIntSize(visibleContentRect().location()); } // Gets the scrolled position as an IntSize. Convenient for adding to other sizes.
     DoubleSize scrollOffsetDouble() const { return DoubleSize(m_scrollPosition.x(), m_scrollPosition.y()); }
     DoubleSize pendingScrollDelta() const { return m_pendingScrollDelta; }
     virtual IntPoint minimumScrollPosition() const override; // The minimum position we can be scrolled to.
     // Adjust the passed in scroll position to keep it between the minimum and maximum positions.
     IntPoint adjustScrollPositionWithinRange(const IntPoint&) const;
     DoublePoint adjustScrollPositionWithinRange(const DoublePoint&) const;
     int scrollX() const { return scrollPosition().x(); }
     int scrollY() const { return scrollPosition().y(); }
 
-    virtual IntSize overhangAmount() const override;
-
     void cacheCurrentScrollPosition() { m_cachedScrollPosition = scrollPositionDouble(); }
     DoublePoint cachedScrollPosition() const { return m_cachedScrollPosition; }
 
     // Functions for scrolling the view.
     void scrollBy(const DoubleSize& s, ScrollBehavior behavior = ScrollBehaviorInstant)
     {
         return setScrollPosition(scrollPositionDouble() + s, behavior);
     }
 
     bool scroll(ScrollDirection, ScrollGranularity);
@@ skipping 93 matching lines @@
     virtual IntRect convertFromContainingViewToScrollbar(const Scrollbar*, const IntRect&) const override;
     virtual IntPoint convertFromScrollbarToContainingView(const Scrollbar*, const IntPoint&) const override;
     virtual IntPoint convertFromContainingViewToScrollbar(const Scrollbar*, const IntPoint&) const override;
 
     virtual bool isFrameView() const override { return true; }
 
     DECLARE_VIRTUAL_TRACE();
     void notifyPageThatContentAreaWillPaint() const;
     FrameView* parentFrameView() const;
 
-    void calculateOverhangAreasForPainting(IntRect& horizontalOverhangRect, IntRect& verticalOverhangRect);
-
     // Returns the scrollable area for the frame.
     ScrollableArea* scrollableArea();
 
     int viewportWidth() const;
 
     LayoutAnalyzer& layoutAnalyzer() { return m_analyzer; }
 
     // LayoutObject for the viewport-defining element (see Document::viewportDefiningElement).
     LayoutObject* viewportLayoutObject() { return m_viewportLayoutObject; }
     void clearViewportLayoutObject() { m_viewportLayoutObject = nullptr; }
@@ skipping 126 matching lines @@
 
     bool adjustScrollbarExistence(ComputeScrollbarExistenceOption = FirstPass);
     void adjustScrollbarOpacity();
     // FIXME(bokan): setScrollOffset, setScrollPosition, scrollTo, scrollToOffsetWithoutAnimation,
     // notifyScrollPositionChanged...there's too many ways to scroll this class. This needs
     // some cleanup.
     void setScrollOffsetFromUpdateScrollbars(const DoubleSize&);
 
     IntRect rectToCopyOnScroll() const;
 
-    void updateOverhangAreas();
-
     bool isFrameViewScrollbar(const Widget* child) const { return horizontalScrollbar() == child || verticalScrollbar() == child; }
 
     ScrollingCoordinator* scrollingCoordinator();
 
     PassRefPtr<TracedValue> analyzerCounters();
 
     LayoutSize m_size;
 
     typedef HashSet<RefPtr<LayoutEmbeddedObject>> EmbeddedObjectSet;
     EmbeddedObjectSet m_partUpdateSet;
@@ skipping 146 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