[TEST] Do not add Scrollbar as child of FrameView.

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

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 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@gmail.com>
@@ skipping 1982 matching lines @@
   } else {
     ScrollbarControlSize scrollbar_size = kRegularScrollbar;
     if (style_source.StyleRef().HasAppearance()) {
       scrollbar_size = LayoutTheme::GetTheme().ScrollbarControlSizeForPart(
           style_source.StyleRef().Appearance());
     }
     scrollbar = Scrollbar::Create(
         ScrollableArea(), orientation, scrollbar_size,
         &ScrollableArea()->Box().GetFrame()->GetPage()->GetChromeClient());
   }
-  ScrollableArea()->Box().GetDocument().View()->AddChild(scrollbar);
   return scrollbar;
 }
 
 void PaintLayerScrollableArea::ScrollbarManager::DestroyScrollbar(
     ScrollbarOrientation orientation) {
   Member<Scrollbar>& scrollbar =
       orientation == kHorizontalScrollbar ? h_bar_ : v_bar_;
   DCHECK(orientation == kHorizontalScrollbar ? !h_bar_is_attached_
                                              : !v_bar_is_attached_);
   if (!scrollbar)
@@ skipping 119 matching lines @@
 
 void PaintLayerScrollableArea::DelayScrollOffsetClampScope::
     ClampScrollableAreas() {
   for (auto& scrollable_area : *needs_clamp_)
     scrollable_area->ClampScrollOffsetAfterOverflowChange();
   delete needs_clamp_;
   needs_clamp_ = nullptr;
 }
 
 }  // namespace blink