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

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

Index: third_party/WebKit/Source/core/layout/ScrollAnchor.h
diff --git a/third_party/WebKit/Source/core/layout/ScrollAnchor.h b/third_party/WebKit/Source/core/layout/ScrollAnchor.h
index 865cabe05762f36a21d409c172928e19d73bc023..1490c6f7ef7f06e3afa93356ba1684003f07b758 100644
--- a/third_party/WebKit/Source/core/layout/ScrollAnchor.h
+++ b/third_party/WebKit/Source/core/layout/ScrollAnchor.h
@@ -34,8 +34,8 @@ class CORE_EXPORT ScrollAnchor final {
   // save() and cached until the next call to clear().
   LayoutObject* anchorObject() const { return m_anchorObject; }
 
-  // Indicates that the next save() should compute a new anchor. (In certain
-  // cases the previous anchor will be reused; see comments in restore.)
+  // Indicates that the next save() should compute a new anchor for the
+  // containing scroller and all ancestor scrollers.
   void clear();
 
   // Records the anchor's location in relation to the scroller. Should be
@@ -64,6 +64,10 @@ class CORE_EXPORT ScrollAnchor final {
   DEFINE_INLINE_TRACE() { visitor->trace(m_scroller); }
 
  private:
+  // Indicates that the next save() should compute a new anchor for the
+  // containing scroller.
+  void clearSelf(bool unconditionally = false);
+
   void findAnchor();
   bool computeScrollAnchorDisablingStyleChanged();