Clear scroll anchor on all parent scrollers from ScrollAnchor::clear

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/layout/ScrollAnchor.h"
 
 #include "core/frame/FrameView.h"
 #include "core/frame/UseCounter.h"
 #include "core/layout/LayoutBlockFlow.h"
 #include "core/layout/api/LayoutBoxItem.h"
@@ skipping 16 matching lines @@
 }
 
 ScrollAnchor::~ScrollAnchor() {}
 
 void ScrollAnchor::setScroller(ScrollableArea* scroller) {
   DCHECK(m_scroller != scroller);
   DCHECK(scroller);
   DCHECK(scroller->isRootFrameViewport() || scroller->isFrameView() ||
          scroller->isPaintLayerScrollableArea());
   m_scroller = scroller;
-  clear();
+  clearForContainingScroller();
 }
 
 // TODO(pilgrim) replace all instances of scrollerLayoutBox with scrollerLayoutBoxItem
 // https://crbug.com/499321
 static LayoutBox* scrollerLayoutBox(const ScrollableArea* scroller) {
   LayoutBox* box = scroller->layoutBox();
   DCHECK(box);
   return box;
 }
 
@@ skipping 167 matching lines @@
   if (m_saved)
     return;
   m_saved = true;
   DCHECK(m_scroller);
 
   ScrollbarOrientation blockLayoutAxis =
       scrollerLayoutBox(m_scroller)->isHorizontalWritingMode()
           ? VerticalScrollbar
           : HorizontalScrollbar;
   if (m_scroller->scrollPosition(blockLayoutAxis) == 0) {
-    clear();
+    clearForContainingScroller();
     return;
   }
 
   if (!m_anchorObject) {
     findAnchor();
     if (!m_anchorObject)
       return;
 
-    m_anchorObject->setIsScrollAnchorObject();
+    m_anchorObject->setIsScrollAnchorObject(true);
     m_savedRelativeOffset =
         computeRelativeOffset(m_anchorObject, m_scroller, m_corner);
   }
 
   // Note that we must compute this during save() since the scroller's
   // descendants have finished layout (and had the bit cleared) by the
   // time restore() is called.
   m_scrollAnchorDisablingStyleChanged =
       computeScrollAnchorDisablingStyleChanged();
 }
@@ skipping 26 matching lines @@
   if (!m_anchorObject)
     return;
   IntSize adjustment = computeAdjustment();
   if (adjustment.isZero())
     return;
 
   if (m_scrollAnchorDisablingStyleChanged) {
     // Note that we only clear if the adjustment would have been non-zero.
     // This minimizes redundant calls to findAnchor.
     // TODO(skobes): add UMA metric for this.
-    clear();
+    clearForContainingScroller();
 
     DEFINE_STATIC_LOCAL(EnumerationHistogram, suppressedBySanaclapHistogram,
                         ("Layout.ScrollAnchor.SuppressedBySanaclap", 2));
     suppressedBySanaclapHistogram.count(1);
 
     return;
   }
 
   m_scroller->setScrollPosition(m_scroller->scrollPositionDouble() + adjustment,
                                 AnchoringScroll);
 
   // Update UMA metric.
   DEFINE_STATIC_LOCAL(EnumerationHistogram, adjustedOffsetHistogram,
                       ("Layout.ScrollAnchor.AdjustedScrollOffset", 2));
   adjustedOffsetHistogram.count(1);
   UseCounter::count(scrollerLayoutBox(m_scroller)->document(),
                     UseCounter::ScrollAnchored);
 }
 
-void ScrollAnchor::clear() {
+void ScrollAnchor::releaseAnchor() {
+  m_anchorObject = nullptr;
+}
+
+void ScrollAnchor::clearForContainingScroller() {
   LayoutObject* anchorObject = m_anchorObject;
-  m_anchorObject = nullptr;
+  releaseAnchor();
 
   if (anchorObject)
     anchorObject->maybeClearIsScrollAnchorObject();
 }
 
+void ScrollAnchor::clear() {
+  if (m_anchorObject)
+    m_anchorObject->clearScrollAnchors();
+  else
+    scrollerLayoutBox(m_scroller)->clearScrollAnchors();
+}
+
 bool ScrollAnchor::refersTo(const LayoutObject* layoutObject) const {
   return m_anchorObject == layoutObject;
 }
 
-void ScrollAnchor::notifyRemoved(LayoutObject* layoutObject) {
-  if (m_anchorObject == layoutObject)
-    clear();
-}
-
 }  // namespace blink