Disable anchoring if ancestor changes padding or margin

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 06ccf0bd6c38fe1c9c4bb7ce0a14c61aa18f2ae0..a6621ac29ecd76fa49942121ffb8f57f1892f512 100644
--- a/third_party/WebKit/Source/core/layout/ScrollAnchor.h
+++ b/third_party/WebKit/Source/core/layout/ScrollAnchor.h
@@ -66,6 +66,8 @@ public:
 private:
     void findAnchor();
 
+    bool paddingOrBorderChanged() const;
+
     enum WalkStatus {
         Skip = 0,
         Constrain,
@@ -132,6 +134,10 @@ private:
 
     // Number of adjustments made since the last clear().
     int m_adjustmentCount;
+
+    // Whether any of the ancestors had their border/padding modified in the
+    // layout pass that triggered scroll anchoring.
+    bool m_anyAncestorChangedPaddingOrMargin;
 };
 
 } // namespace blink