Implement "create an element" when async for Custom Element V1

third_party/WebKit/Source/core/dom/custom/CustomElement.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 CustomElement_h
 #define CustomElement_h
 
 #include "core/CoreExport.h"
 #include "core/HTMLNames.h"
 #include "core/dom/Element.h"
 #include "wtf/Allocator.h"
 #include "wtf/text/AtomicString.h"
 
 namespace blink {
 
 class Document;
 class Element;
 class HTMLElement;
 class QualifiedName;
 class CustomElementDefinition;
 class CustomElementRegistry;
 
 class CORE_EXPORT CustomElement {
     STATIC_ONLY(CustomElement);
 public:
     // Retrieves the CustomElementsRegistry for Element, if any. This
     // may be a different object for a given element over its lifetime
     // as it moves between documents.
     static CustomElementsRegistry* registry(const Element&);
+    static CustomElementsRegistry* registry(const Document&);
 
     // Returns true if element could possibly match a custom element
     // descriptor *now*. See CustomElementDescriptor::matches for the
     // meaning of "match". Custom element processing which depends on
     // matching a descriptor, such as upgrade, can be skipped for
     // elements that fail this test.
     //
     // Although this result is currently constant for a given element,
     // when customized built-in elements are implemented the result
     // will depend on the value of the 'is' attribute. In addition,
@@ skipping 10 matching lines @@
 
     static bool isValidName(const AtomicString& name);
 
     static bool shouldCreateCustomElement(Document&, const AtomicString& localName);
     static bool shouldCreateCustomElement(Document&, const QualifiedName&);
 
     static HTMLElement* createCustomElement(Document&, const AtomicString& localName, CreateElementFlags);
     static HTMLElement* createCustomElement(Document&, const QualifiedName&, CreateElementFlags);
 
     static void enqueueUpgradeReaction(Element*, CustomElementDefinition*);
+
+private:
+    static HTMLElement* createCustomElementAsync(Document&, CustomElementDefinition&, const QualifiedName&);
 };
 
 } // namespace blink
 
 #endif // CustomElement_h