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

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

 /*
  * Copyright (C) 2013 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 22 matching lines @@
 
 #include "platform/scroll/ScrollbarThemeMacCommon.h"
 
 typedef id ScrollbarPainter;
 
 namespace blink {
 
 class PLATFORM_EXPORT ScrollbarThemeMacOverlayAPI : public ScrollbarThemeMacCommon {
 public:
     bool shouldRepaintAllPartsOnInvalidation() const override { return false; }
-    void updateEnabledState(const ScrollbarThemeClient*) override;
+    void updateEnabledState(const ScrollbarThemeClient&) override;
     int scrollbarThickness(ScrollbarControlSize = RegularScrollbar) override;
     bool usesOverlayScrollbars() const override;
-    void updateScrollbarOverlayStyle(const ScrollbarThemeClient*) override;
+    void updateScrollbarOverlayStyle(const ScrollbarThemeClient&) override;
     ScrollbarButtonsPlacement buttonsPlacement() const override;
 
-    void registerScrollbar(ScrollbarThemeClient*) override;
-    void unregisterScrollbar(ScrollbarThemeClient*) override;
+    void registerScrollbar(ScrollbarThemeClient&) override;
+    void unregisterScrollbar(ScrollbarThemeClient&) override;
 
-    void setNewPainterForScrollbar(ScrollbarThemeClient*, ScrollbarPainter);
-    ScrollbarPainter painterForScrollbar(const ScrollbarThemeClient*) const;
+    void setNewPainterForScrollbar(ScrollbarThemeClient&, ScrollbarPainter);
+    ScrollbarPainter painterForScrollbar(const ScrollbarThemeClient&) const;
 
-    void paintTrackBackground(GraphicsContext*, const ScrollbarThemeClient*, const IntRect&) override;
-    void paintThumb(GraphicsContext*, const ScrollbarThemeClient*, const IntRect&) override;
+    void paintTrackBackground(GraphicsContext&, const ScrollbarThemeClient&, const IntRect&) override;
+    void paintThumb(GraphicsContext&, const ScrollbarThemeClient&, const IntRect&) override;
 
-    float thumbOpacity(const ScrollbarThemeClient*) const override;
+    float thumbOpacity(const ScrollbarThemeClient&) const override;
 
 protected:
-    IntRect trackRect(const ScrollbarThemeClient*, bool painting = false) override;
-    IntRect backButtonRect(const ScrollbarThemeClient*, ScrollbarPart, bool painting = false) override;
-    IntRect forwardButtonRect(const ScrollbarThemeClient*, ScrollbarPart, bool painting = false) override;
+    IntRect trackRect(const ScrollbarThemeClient&, bool painting = false) override;
+    IntRect backButtonRect(const ScrollbarThemeClient&, ScrollbarPart, bool painting = false) override;
+    IntRect forwardButtonRect(const ScrollbarThemeClient&, ScrollbarPart, bool painting = false) override;
 
-    bool hasButtons(const ScrollbarThemeClient*) override { return false; }
-    bool hasThumb(const ScrollbarThemeClient*) override;
+    bool hasButtons(const ScrollbarThemeClient&) override { return false; }
+    bool hasThumb(const ScrollbarThemeClient&) override;
 
-    int minimumThumbLength(const ScrollbarThemeClient*) override;
+    int minimumThumbLength(const ScrollbarThemeClient&) override;
 };
 
 }
 
 #endif