Update scrollbars from FrameView::show.

third_party/WebKit/Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 3994 matching lines @@
 
     if (!isSelfVisible())
         return;
 
     for (const auto& child : m_children)
         child->setParentVisible(visible);
 }
 
 void FrameView::show()
 {
+    setNeedsLayout();
     if (!isSelfVisible()) {
         setSelfVisible(true);
         setNeedsCompositingUpdate(layoutViewItem(), CompositingUpdateRebuildTree);
         updateScrollableAreaSet();
         if (isParentVisible()) {
             for (const auto& child : m_children)
                 child->setParentVisible(true);
         }
     }
 
@@ skipping 221 matching lines @@
     return m_subtreeThrottled || (m_hiddenForThrottling && m_crossOriginForThrottling);
 }
 
 LayoutBox& FrameView::boxForScrollControlPaintInvalidation() const
 {
     ASSERT(!layoutViewItem().isNull());
     return *layoutView();
 }
 
 } // namespace blink