Scrollbar no longer inherits from FrameViewBase.

third_party/WebKit/Source/platform/exported/WebScrollbarThemeClientImpl.h

 /*
  * Copyright (C) 2012 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:
  *
  * 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 35 matching lines @@
   WebScrollbarThemeClientImpl(WebScrollbar&);
   ~WebScrollbarThemeClientImpl() override;
 
   // Implement ScrollbarThemeClient interface
   int X() const override;
   int Y() const override;
   int Width() const override;
   int Height() const override;
   IntSize Size() const override;
   IntPoint Location() const override;
-  FrameViewBase* Parent() const override;
-  FrameViewBase* Root() const override;
   void SetFrameRect(const IntRect&) override;
   IntRect FrameRect() const override;
   void Invalidate() override;
   void InvalidateRect(const IntRect&) override;
   ScrollbarOverlayColorTheme GetScrollbarOverlayColorTheme() const override;
   void GetTickmarks(Vector<IntRect>&) const override;
   bool IsScrollableAreaActive() const override;
   IntPoint ConvertFromRootFrame(const IntPoint&) const override;
   bool IsCustomScrollbar() const override;
   ScrollbarOrientation Orientation() const override;
@@ skipping 14 matching lines @@
   float ElasticOverscroll() const override;
   void SetElasticOverscroll(float) override;
 
  private:
   WebScrollbar& scrollbar_;
 };
 
 }  // namespace blink
 
 #endif  // WebScrollbarThemeClientImpl_h