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

third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 175 matching lines @@
     GraphicsLayer* layerForHorizontalScrollbar() const override;
     GraphicsLayer* layerForVerticalScrollbar() const override;
     GraphicsLayer* layerForScrollCorner() const override;
 
     bool usesCompositedScrolling() const override;
     void scrollControlWasSetNeedsPaintInvalidation() override;
     bool shouldUseIntegerScrollOffset() const override;
     bool isActive() const override;
     bool isScrollCornerVisible() const override;
     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;
     int scrollSize(ScrollbarOrientation) const override;
     IntPoint scrollPosition() const override;
     DoublePoint scrollPositionDouble() const override;
     IntPoint minimumScrollPosition() const override;
     IntPoint maximumScrollPosition() const override;
     IntRect visibleContentRect(IncludeScrollbarsInRect = ExcludeScrollbars) const override;
     int visibleHeight() const override;
     int visibleWidth() const override;
     IntSize contentsSize() const override;
     IntPoint lastKnownMousePosition() const override;
@@ skipping 131 matching lines @@
 
     bool needsScrollbarReconstruction() const;
 
     void computeScrollDimensions();
 
     void setScrollOffset(const IntPoint&, ScrollType) override;
     void setScrollOffset(const DoublePoint&, ScrollType) override;
 
     LayoutUnit verticalScrollbarStart(int minX, int maxX) const;
     LayoutUnit horizontalScrollbarStart(int minX) const;
-    IntSize scrollbarOffset(const Scrollbar*) const;
+    IntSize scrollbarOffset(const Scrollbar&) const;
 
     void setHasHorizontalScrollbar(bool hasScrollbar);
     void setHasVerticalScrollbar(bool hasScrollbar);
 
     void updateScrollCornerStyle();
 
     // See comments on isPointInResizeControl.
     void updateResizerAreaSet();
     void updateResizerStyle();
 
@@ skipping 41 matching lines @@
     LayoutScrollbarPart* m_resizer;
 
 #if ENABLE(ASSERT)
     bool m_hasBeenDisposed;
 #endif
 };
 
 } // namespace blink
 
 #endif // LayerScrollableArea_h