Recursively defining custom elements should not lead to redefinition

third_party/WebKit/Source/core/dom/custom/CustomElementsRegistry.h

 // Copyright 2016 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.
 
 #ifndef CustomElementsRegistry_h
 #define CustomElementsRegistry_h
 
 #include "base/gtest_prod_util.h"
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "core/CoreExport.h"
 #include "platform/heap/Handle.h"
+#include "wtf/HashSet.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/text/AtomicString.h"
 #include "wtf/text/AtomicStringHash.h"
 
 namespace blink {
 
 class CustomElementDefinition;
 class CustomElementDefinitionBuilder;
 class CustomElementDescriptor;
 class Document;
 class Element;
 class ElementRegistrationOptions;
 class ExceptionState;
 class ScriptState;
 class ScriptValue;
 class V0CustomElementRegistrationContext;
 
 class CORE_EXPORT CustomElementsRegistry final
-    : public GarbageCollected<CustomElementsRegistry>
+    : public GarbageCollectedFinalized<CustomElementsRegistry>
     , public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
     WTF_MAKE_NONCOPYABLE(CustomElementsRegistry);
 public:
     static CustomElementsRegistry* create(Document*);
 
+    virtual ~CustomElementsRegistry() = default;
+
     void define(
         ScriptState*,
         const AtomicString& name,
         const ScriptValue& constructor,
         const ElementRegistrationOptions&,
         ExceptionState&);
 
     void define(
         const AtomicString& name,
         CustomElementDefinitionBuilder&,
@@ skipping 15 matching lines @@
 
     CustomElementsRegistry(Document*);
 
     V0CustomElementRegistrationContext* v0();
     bool v0NameIsDefined(const AtomicString& name);
 
     void collectCandidates(
         const CustomElementDescriptor&,
         HeapVector<Member<Element>>*);
 
+    class NameIsBeingDefined;
+
+    HashSet<AtomicString> m_namesBeingDefined;
     using DefinitionMap =
         HeapHashMap<AtomicString, Member<CustomElementDefinition>>;
     DefinitionMap m_definitions;
 
     Member<Document> m_document;
 
     using UpgradeCandidateSet = HeapHashSet<WeakMember<Element>>;
     using UpgradeCandidateMap = HeapHashMap<
         AtomicString,
         Member<UpgradeCandidateSet>>;
     Member<UpgradeCandidateMap> m_upgradeCandidates;
 };
 
 } // namespace blink
 
 #endif // CustomElementsRegistry_h