Tie scroll anchoring adjustments to frame lifecycle instead of layout.

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

 /*
    Copyright (C) 1997 Martin Jones (mjones@kde.org)
              (C) 1998 Waldo Bastian (bastian@kde.org)
              (C) 1998, 1999 Torben Weis (weis@kde.org)
              (C) 1999 Lars Knoll (knoll@kde.org)
              (C) 1999 Antti Koivisto (koivisto@kde.org)
    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights
    reserved.
 
    This library is free software; you can redistribute it and/or
@@ skipping 710 matching lines @@
 
   // TODO(ojan): Merge this with IntersectionObserver once it lands.
   IntRect computeVisibleArea();
 
   // Viewport size that should be used for viewport units (i.e. 'vh'/'vw').
   FloatSize viewportSizeForViewportUnits() const;
 
   ScrollAnchor* scrollAnchor() override { return &m_scrollAnchor; }
   void clearScrollAnchor();
   bool shouldPerformScrollAnchoring() const override;
+  void enqueueScrollAnchoringAdjustment(ScrollableArea*);
+  void performScrollAnchoringAdjustments();
 
   // For PaintInvalidator temporarily. TODO(wangxianzhu): Move into
   // PaintInvalidator.
   void invalidatePaintIfNeeded(const PaintInvalidationState&);
 
   // Only for SPv2.
   std::unique_ptr<JSONObject> compositedLayersAsJSON(LayerTreeFlags);
 
  protected:
   // Scroll the content via the compositor.
@@ skipping 328 matching lines @@
   RefPtr<ClipPaintPropertyNode> m_contentClip;
   // The property tree state that should be used for painting contents. These
   // properties are either created by this FrameView or are inherited from
   // an ancestor.
   std::unique_ptr<PropertyTreeState> m_totalPropertyTreeStateForContents;
 
   // This is set on the local root frame view only.
   DocumentLifecycle::LifecycleState m_currentUpdateLifecyclePhasesTargetState;
 
   ScrollAnchor m_scrollAnchor;
+  using AnchoringAdjustmentQueue =
+      HeapLinkedHashSet<WeakMember<ScrollableArea>>;
+  AnchoringAdjustmentQueue m_anchoringAdjustmentQueue;
 
   // ScrollbarManager holds the Scrollbar instances.
   ScrollbarManager m_scrollbarManager;
 
   bool m_needsScrollbarsUpdate;
   bool m_suppressAdjustViewSize;
   bool m_allowsLayoutInvalidationAfterLayoutClean;
 
   // For testing.
   struct ObjectPaintInvalidation {
@@ skipping 39 matching lines @@
                   widget.isFrameView());
 DEFINE_TYPE_CASTS(FrameView,
                   ScrollableArea,
                   scrollableArea,
                   scrollableArea->isFrameView(),
                   scrollableArea.isFrameView());
 
 }  // namespace blink
 
 #endif  // FrameView_h