Scrollbar no longer inherits from FrameViewBase.

third_party/WebKit/Source/platform/scroll/Scrollbar.cpp

 /*
  * Copyright (C) 2004, 2006, 2008 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 45 matching lines @@
       pressed_pos_(0),
       scroll_pos_(0),
       dragging_document_(false),
       document_drag_pos_(0),
       enabled_(true),
       scroll_timer_(scrollable_area->GetTimerTaskRunner(),
                     this,
                     &Scrollbar::AutoscrollTimerFired),
       elastic_overscroll_(0),
       track_needs_repaint_(true),
-      thumb_needs_repaint_(true) {
+      thumb_needs_repaint_(true),
+      parent_(nullptr) {
   theme_.RegisterScrollbar(*this);
 
   // FIXME: This is ugly and would not be necessary if we fix cross-platform
   // code to actually query for scrollbar thickness and use it when sizing
   // scrollbars (rather than leaving one dimension of the scrollbar alone when
   // sizing).
   int thickness = theme_.ScrollbarThickness(control_size);
   theme_scrollbar_thickness_ = thickness;
   if (chrome_client_)
     thickness = chrome_client_->WindowToViewportScalar(thickness);
-  FrameViewBase::SetFrameRect(IntRect(0, 0, thickness, thickness));
+  frame_rect_ = IntRect(0, 0, thickness, thickness);
 
   current_pos_ = ScrollableAreaCurrentPos();
 }
 
 Scrollbar::~Scrollbar() {
   theme_.UnregisterScrollbar(*this);
 }
 
 DEFINE_TRACE(Scrollbar) {
   visitor->Trace(scrollable_area_);
   visitor->Trace(chrome_client_);
-  FrameViewBase::Trace(visitor);
+  visitor->Trace(parent_);
 }
 
 void Scrollbar::SetFrameRect(const IntRect& frame_rect) {
-  if (frame_rect == this->FrameRect())
+  if (frame_rect == frame_rect_)
     return;
 
-  FrameViewBase::SetFrameRect(frame_rect);
+  frame_rect_ = frame_rect;
   SetNeedsPaintInvalidation(kAllParts);
   if (scrollable_area_)
     scrollable_area_->ScrollbarFrameRectChanged();
 }
 
 ScrollbarOverlayColorTheme Scrollbar::GetScrollbarOverlayColorTheme() const {
   return scrollable_area_ ? scrollable_area_->GetScrollbarOverlayColorTheme()
                           : kScrollbarOverlayColorThemeDark;
 }
 
@@ skipping 532 matching lines @@
     invalid_parts = kAllParts;
   if (invalid_parts & ~kThumbPart)
     track_needs_repaint_ = true;
   if (invalid_parts & kThumbPart)
     thumb_needs_repaint_ = true;
   if (scrollable_area_)
     scrollable_area_->SetScrollbarNeedsPaintInvalidation(Orientation());
 }
 
 }  // namespace blink