Rename Sky's custom2 to custom

sky/engine/core/dom/custom/custom_element.h

 // Copyright 2015 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 SKY_ENGINE_CORE_DOM_CUSTOM_NEW_CUSTOM_ELEMENT_H_
 #define SKY_ENGINE_CORE_DOM_CUSTOM_NEW_CUSTOM_ELEMENT_H_
 
 #include "sky/engine/wtf/text/AtomicString.h"
 
 namespace blink {
 class Document;
 class Element;
 
-class NewCustomElement {
+class CustomElement {
  public:
   static void AttributeDidChange(Element*, const AtomicString& name, const AtomicString& oldValue, const AtomicString& newValue);
   static void DidAttach(Element*, Document&);
   static void DidDetach(Element*, Document&);
 
  private:
-  NewCustomElement();
+  CustomElement();
 };
 
 }  // namespace blink
 
 #endif  // SKY_ENGINE_CORE_DOM_CUSTOM_NEW_CUSTOM_ELEMENT_H_