Use refs for non-null GraphicsContext, Scrollbar, etc. in scrollbar related code

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 306 matching lines @@
     typedef HashSet<LayoutBox*> ResizerAreaSet;
     void addResizerArea(LayoutBox&);
     void removeResizerArea(LayoutBox&);
     const ResizerAreaSet* resizerAreas() const { return m_resizerAreas.get(); }
 
     bool shouldUseIntegerScrollOffset() const override;
 
     bool isActive() const override;
 
     // Override scrollbar notifications to update the AXObject cache.
-    void didAddScrollbar(Scrollbar*, ScrollbarOrientation) override;
+    void didAddScrollbar(Scrollbar&, ScrollbarOrientation) override;
 
     // FIXME: This should probably be renamed as the 'inSubtreeLayout' parameter
     // passed around the FrameView layout methods can be true while this returns
     // false.
     bool isSubtreeLayout() const { return !m_layoutSubtreeRootList.isEmpty(); }
 
     // Sets the tickmarks for the FrameView, overriding the default behavior
     // which is to display the tickmarks corresponding to find results.
     // If |m_tickmarks| is empty, the default behavior is restored.
     void setTickmarks(const Vector<IntRect>& tickmarks)
@@ skipping 167 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 CullRect&) const override;
-    void paint(GraphicsContext*, const GlobalPaintFlags, const CullRect&) const;
-    void paintContents(GraphicsContext*, const GlobalPaintFlags, const IntRect& damageRect) 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;
 
-    IntRect convertFromScrollbarToContainingWidget(const Scrollbar*, const IntRect&) const override;
-    IntRect convertFromContainingWidgetToScrollbar(const Scrollbar*, const IntRect&) const override;
-    IntPoint convertFromScrollbarToContainingWidget(const Scrollbar*, const IntPoint&) const override;
-    IntPoint convertFromContainingWidgetToScrollbar(const Scrollbar*, const IntPoint&) const override;
+    IntRect convertFromScrollbarToContainingWidget(const Scrollbar&, const IntRect&) const override;
+    IntRect convertFromContainingWidgetToScrollbar(const Scrollbar&, const IntRect&) const override;
+    IntPoint convertFromScrollbarToContainingWidget(const Scrollbar&, const IntPoint&) const override;
+    IntPoint convertFromContainingWidgetToScrollbar(const Scrollbar&, const IntPoint&) const override;
 
     bool isFrameView() const override { return true; }
 
     DECLARE_VIRTUAL_TRACE();
     void notifyPageThatContentAreaWillPaint() const;
     FrameView* parentFrameView() const;
 
     // Returns the scrollable area for the frame. For the root frame, this will
     // be the RootFrameViewport, which adds pinch-zoom semantics to scrolling.
     // For non-root frames, this will be the the ScrollableArea used by the
@@ skipping 56 matching lines @@
     void scrollContentsIfNeeded();
 
     void setScrollOrigin(const IntPoint&, bool updatePositionAtAll, bool updatePositionSynchronously);
 
     enum ComputeScrollbarExistenceOption {
         FirstPass,
         Incremental
     };
     void computeScrollbarExistence(bool& newHasHorizontalScrollbar, bool& newHasVerticalScrollbar, const IntSize& docSize, ComputeScrollbarExistenceOption = FirstPass) const;
     void updateScrollbarGeometry();
-    IntRect adjustScrollbarRectForResizer(const IntRect&, Scrollbar*);
+    IntRect adjustScrollbarRectForResizer(const IntRect&, Scrollbar&);
 
     // Called to update the scrollbars to accurately reflect the state of the view.
     void updateScrollbars(const DoubleSize& desiredOffset);
 
     class InUpdateScrollbarsScope {
         STACK_ALLOCATED();
     public:
         explicit InUpdateScrollbarsScope(FrameView* view)
             : m_scope(view->m_inUpdateScrollbars, true)
         { }
@@ skipping 296 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