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

third_party/WebKit/Source/platform/scroll/ScrollableArea.h

 /*
  * Copyright (C) 2008, 2011 Apple Inc. All Rights Reserved.
  *
  * 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 88 matching lines @@
     static bool scrollBehaviorFromString(const String&, ScrollBehavior&);
 
     bool inLiveResize() const { return m_inLiveResize; }
     void willStartLiveResize();
     void willEndLiveResize();
 
     void contentAreaWillPaint() const;
     void mouseEnteredContentArea() const;
     void mouseExitedContentArea() const;
     void mouseMovedInContentArea() const;
-    void mouseEnteredScrollbar(Scrollbar*) const;
-    void mouseExitedScrollbar(Scrollbar*) const;
+    void mouseEnteredScrollbar(Scrollbar&) const;
+    void mouseExitedScrollbar(Scrollbar&) const;
     void contentAreaDidShow() const;
     void contentAreaDidHide() const;
 
     void finishCurrentScrollAnimations() const;
 
-    virtual void didAddScrollbar(Scrollbar*, ScrollbarOrientation);
-    virtual void willRemoveScrollbar(Scrollbar*, ScrollbarOrientation);
+    virtual void didAddScrollbar(Scrollbar&, ScrollbarOrientation);
+    virtual void willRemoveScrollbar(Scrollbar&, ScrollbarOrientation);
 
     virtual void contentsResized();
 
     bool hasOverlayScrollbars() const;
     void setScrollbarOverlayStyle(ScrollbarOverlayStyle);
     ScrollbarOverlayStyle scrollbarOverlayStyle() const { return static_cast<ScrollbarOverlayStyle>(m_scrollbarOverlayStyle); }
 
     // This getter will create a ScrollAnimatorBase if it doesn't already exist.
-    ScrollAnimatorBase* scrollAnimator() const;
+    ScrollAnimatorBase& scrollAnimator() const;
 
     // This getter will return null if the ScrollAnimatorBase hasn't been created yet.
     ScrollAnimatorBase* existingScrollAnimator() const { return m_scrollAnimator.get(); }
 
-    ProgrammaticScrollAnimator* programmaticScrollAnimator() const;
+    ProgrammaticScrollAnimator& programmaticScrollAnimator() const;
     ProgrammaticScrollAnimator* existingProgrammaticScrollAnimator() const { return m_programmaticScrollAnimator.get(); }
 
     const IntPoint& scrollOrigin() const { return m_scrollOrigin; }
     bool scrollOriginChanged() const { return m_scrollOriginChanged; }
 
 
     // This is used to determine whether the incoming fractional scroll offset should
     // be truncated to integer. Current rule is that if preferCompositingToLCDTextEnabled()
     // is disabled (which is true on low-dpi device by default) we should do the truncation.
     // The justification is that non-composited elements using fractional scroll offsets
     // is causing too much nasty bugs but does not add too benefit on low-dpi devices.
     virtual bool shouldUseIntegerScrollOffset() const { return !RuntimeEnabledFeatures::fractionalScrollOffsetsEnabled(); }
 
     virtual bool isActive() const = 0;
     virtual int scrollSize(ScrollbarOrientation) const = 0;
-    void setScrollbarNeedsPaintInvalidation(Scrollbar*);
+    void setScrollbarNeedsPaintInvalidation(ScrollbarOrientation);
     virtual bool isScrollCornerVisible() const = 0;
     virtual IntRect scrollCornerRect() const = 0;
     void setScrollCornerNeedsPaintInvalidation();
     virtual void getTickmarks(Vector<IntRect>&) const { }
 
     // Convert points and rects between the scrollbar and its containing Widget.
     // The client needs to implement these in order to be aware of layout effects
     // like CSS transforms.
-    virtual IntRect convertFromScrollbarToContainingWidget(const Scrollbar* scrollbar, const IntRect& scrollbarRect) const
+    virtual IntRect convertFromScrollbarToContainingWidget(const Scrollbar& scrollbar, const IntRect& scrollbarRect) const
     {
-        return scrollbar->Widget::convertToContainingWidget(scrollbarRect);
+        return scrollbar.Widget::convertToContainingWidget(scrollbarRect);
     }
-    virtual IntRect convertFromContainingWidgetToScrollbar(const Scrollbar* scrollbar, const IntRect& parentRect) const
+    virtual IntRect convertFromContainingWidgetToScrollbar(const Scrollbar& scrollbar, const IntRect& parentRect) const
     {
-        return scrollbar->Widget::convertFromContainingWidget(parentRect);
+        return scrollbar.Widget::convertFromContainingWidget(parentRect);
     }
-    virtual IntPoint convertFromScrollbarToContainingWidget(const Scrollbar* scrollbar, const IntPoint& scrollbarPoint) const
+    virtual IntPoint convertFromScrollbarToContainingWidget(const Scrollbar& scrollbar, const IntPoint& scrollbarPoint) const
     {
-        return scrollbar->Widget::convertToContainingWidget(scrollbarPoint);
+        return scrollbar.Widget::convertToContainingWidget(scrollbarPoint);
     }
-    virtual IntPoint convertFromContainingWidgetToScrollbar(const Scrollbar* scrollbar, const IntPoint& parentPoint) const
+    virtual IntPoint convertFromContainingWidgetToScrollbar(const Scrollbar& scrollbar, const IntPoint& parentPoint) const
     {
-        return scrollbar->Widget::convertFromContainingWidget(parentPoint);
+        return scrollbar.Widget::convertFromContainingWidget(parentPoint);
     }
 
-    virtual Scrollbar* horizontalScrollbar() const { return 0; }
-    virtual Scrollbar* verticalScrollbar() const { return 0; }
+    virtual Scrollbar* horizontalScrollbar() const { return nullptr; }
+    virtual Scrollbar* verticalScrollbar() const { return nullptr; }
 
     // scrollPosition is relative to the scrollOrigin. i.e. If the page is RTL
     // then scrollPosition will be negative. By default, scrollPositionDouble()
     // just call into scrollPosition(). Subclass can override scrollPositionDouble()
     // to return floating point precision scrolloffset.
     // FIXME: Remove scrollPosition(). crbug.com/414283.
     virtual IntPoint scrollPosition() const = 0;
     virtual DoublePoint scrollPositionDouble() const { return DoublePoint(scrollPosition()); }
     virtual IntPoint minimumScrollPosition() const = 0;
     virtual DoublePoint minimumScrollPositionDouble() const { return DoublePoint(minimumScrollPosition()); }
@@ skipping 160 matching lines @@
     // vertical-lr / ltr            NO                      NO
     // vertical-lr / rtl            NO                      YES
     // vertical-rl / ltr            YES                     NO
     // vertical-rl / rtl            YES                     YES
     IntPoint m_scrollOrigin;
 };
 
 } // namespace blink
 
 #endif // ScrollableArea_h