| Index: third_party/WebKit/Source/core/dom/custom/CustomElementUpgradeSorter.h | 
| diff --git a/third_party/WebKit/Source/core/dom/custom/CustomElementUpgradeSorter.h b/third_party/WebKit/Source/core/dom/custom/CustomElementUpgradeSorter.h | 
| index 5892539ba02421d0b3354d8f9fbe827b38b8bd2d..89d4e0d8b42fe1dadea02c705085fa7b3244863d 100644 | 
| --- a/third_party/WebKit/Source/core/dom/custom/CustomElementUpgradeSorter.h | 
| +++ b/third_party/WebKit/Source/core/dom/custom/CustomElementUpgradeSorter.h | 
| @@ -34,6 +34,12 @@ private: | 
| using ChildSet = HeapHashSet<Member<Node>>; | 
| using ParentChildMap = HeapHashMap<Member<Node>, ChildSet>; | 
|  | 
| +    enum AddResult { | 
| +        kParentAlreadyExistsInMap, | 
| +        kParentAddedToMap | 
| +    }; | 
| + | 
| +    AddResult addToParentChildMap(Node* parent, Node* child); | 
| void visit( | 
| HeapVector<Member<Element>>* result, | 
| ChildSet&, | 
|  |