Tie scroll anchoring adjustments to frame lifecycle instead of layout.

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

 /*
  * Copyright (c) 2010, Google Inc. All rights reserved.
  * Copyright (C) 2008, 2011 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 166 matching lines @@
                                      ScrollBehavior behavior) {
   ScrollOffset clampedOffset = clampScrollOffset(offset);
   if (clampedOffset == scrollOffset())
     return;
 
   if (behavior == ScrollBehaviorAuto)
     behavior = scrollBehaviorStyle();
 
   switch (scrollType) {
     case CompositorScroll:
+    case ClampingScroll:
       scrollOffsetChanged(clampedOffset, scrollType);
       break;
     case AnchoringScroll:
       scrollAnimator().adjustAnimationAndSetScrollOffset(clampedOffset,
                                                          scrollType);
       break;
     case ProgrammaticScroll:
       programmaticScrollHelper(clampedOffset, behavior);
       break;
     case UserScroll:
@@ skipping 393 matching lines @@
   return IntSize(std::max(0, size.width() - verticalScrollbarWidth()),
                  std::max(0, size.height() - horizontalScrollbarHeight()));
 }
 
 DEFINE_TRACE(ScrollableArea) {
   visitor->trace(m_scrollAnimator);
   visitor->trace(m_programmaticScrollAnimator);
 }
 
 }  // namespace blink