Refactor scroll updates after layout.

third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 313 matching lines @@
     Parent()->SetNeedsLayout(LayoutInvalidationReason::kChildChanged,
                              kMarkContainerChain);
 
   PaintLayerType type = LayerTypeRequired();
   if (type != kNoPaintLayer) {
     if (!Layer() && LayerCreationAllowedForSubtree()) {
       if (was_floating_before_style_changed && IsFloating())
         SetChildNeedsLayout();
       CreateLayerAfterStyleChange();
       if (Parent() && !NeedsLayout()) {
-        // FIXME: We should call a specialized version of this function.
+        // FIXME: We should call specialized versions of these functions.
+        Layer()->UpdateScrollingAfterLayout();
         Layer()->UpdateLayerPositionsAfterLayout();
       }
     }
   } else if (Layer() && Layer()->Parent()) {
     PaintLayer* parent_layer = Layer()->Parent();
     // Either a transform wasn't specified or the object doesn't support
     // transforms, so just null out the bit.
     SetHasTransformRelatedProperty(false);
     SetHasReflection(false);
     Layer()->UpdateFilters(old_style, StyleRef());
@@ skipping 1136 matching lines @@
   if (root_element_style->HasBackground())
     return false;
 
   if (GetNode() != GetDocument().FirstBodyElement())
     return false;
 
   return true;
 }
 
 }  // namespace blink