Refactor ScrollView::updateScrollbars()

Source/platform/scroll/ScrollView.h

 /*
  * Copyright (C) 2004, 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Holger Hans Peter Freyther
  *
  * 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
@@ skipping 102 matching lines @@
     // Overridden by FrameView to create custom CSS scrollbars if applicable.
     virtual PassRefPtr<Scrollbar> createScrollbar(ScrollbarOrientation);
 
     virtual bool shouldAttemptToScrollUsingFastPath() const;
 
     // The visible content rect has a location that is the scrolled offset of the document. The width and height are the viewport width
     // and height. By default the scrollbars themselves are excluded from this rectangle, but an optional boolean argument allows them to be
     // included.
     virtual IntRect visibleContentRect(IncludeScrollbarsInRect = ExcludeScrollbars) const OVERRIDE;
     IntSize visibleSize() const { return visibleContentRect().size(); }
-    virtual int visibleWidth() const OVERRIDE { return visibleContentRect().width(); }
-    virtual int visibleHeight() const OVERRIDE { return visibleContentRect().height(); }
+    virtual int visibleWidth() const OVERRIDE FINAL { return visibleContentRect().width(); }
+    virtual int visibleHeight() const OVERRIDE FINAL { return visibleContentRect().height(); }
 
     // visibleContentRect().size() is computed from unscaledVisibleContentSize() divided by the value of visibleContentScaleFactor.
     // For the main frame, visibleContentScaleFactor is equal to the page's pageScaleFactor; it's 1 otherwise.
     IntSize unscaledVisibleContentSize(IncludeScrollbarsInRect = ExcludeScrollbars) const;
     virtual float visibleContentScaleFactor() const { return 1; }
 
     // Offset used to convert incoming input events while emulating device metics.
     virtual IntSize inputEventsOffsetForEmulation() const { return IntSize(); }
 
     // Scale used to convert incoming input events. Usually the same as visibleContentScaleFactor(), unless specifically changed.
@@ skipping 139 matching lines @@
     virtual bool scrollContentsFastPath(const IntSize& scrollDelta, const IntRect& rectToScroll, const IntRect& clipRect);
     // Scroll the content by invalidating everything.
     virtual void scrollContentsSlowPath(const IntRect& updateRect);
 
     void setScrollOrigin(const IntPoint&, bool updatePositionAtAll, bool updatePositionSynchronously);
 
     // Subclassed by FrameView to check the writing-mode of the document.
     virtual bool isVerticalDocument() const { return true; }
     virtual bool isFlippedDocument() const { return false; }
 
+    enum ComputeScrollbarExistenceOption {
+        FirstPass,
+        Incremental
+    };
+    void computeScrollbarExistence(bool& newHasHorizontalScrollbar, bool& newHasVerticalScrollbar, ComputeScrollbarExistenceOption = FirstPass) const;
+    void updateScrollbarGeometry();
+
     // Called to update the scrollbars to accurately reflect the state of the view.
     void updateScrollbars(const IntSize& desiredOffset);
 
     IntSize excludeScrollbars(const IntSize&) const;
 
 private:
+    bool adjustScrollbarExistence(ComputeScrollbarExistenceOption = FirstPass);
+
     RefPtr<Scrollbar> m_horizontalScrollbar;
     RefPtr<Scrollbar> m_verticalScrollbar;
     ScrollbarMode m_horizontalScrollbarMode;
     ScrollbarMode m_verticalScrollbarMode;
 
     bool m_horizontalScrollbarLock;
     bool m_verticalScrollbarLock;
 
     HashSet<RefPtr<Widget> > m_children;
 
     IntSize m_pendingScrollDelta;
     IntSize m_scrollOffset; // FIXME: Would rather store this as a position, but we will wait to make this change until more code is shared.
     IntPoint m_cachedScrollPosition;
     IntSize m_contentsSize;
 
     int m_scrollbarsAvoidingResizer;
     bool m_scrollbarsSuppressed;
 
     bool m_inUpdateScrollbars;
-    unsigned m_updateScrollbarsPass;
 
     IntPoint m_panScrollIconPoint;
     bool m_drawPanScrollIcon;
 
     bool m_paintsEntireContents;
     bool m_clipsRepaints;
 
     void init();
     void destroy();
 
     IntRect rectToCopyOnScroll() const;
 
     void calculateOverhangAreasForPainting(IntRect& horizontalOverhangRect, IntRect& verticalOverhangRect);
     void updateOverhangAreas();
 }; // class ScrollView
 
 DEFINE_TYPE_CASTS(ScrollView, Widget, widget, widget->isScrollView(), widget.isScrollView());
 
 } // namespace WebCore
 
 #endif // ScrollView_h