Add detailed use counters for document.registerElement use.

third_party/WebKit/Source/bindings/core/v8/V0CustomElementConstructorBuilder.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 30 matching lines @@
 #include "bindings/core/v8/V8PerContextData.h"
 #include "bindings/core/v8/V8SVGElement.h"
 #include "core/HTMLNames.h"
 #include "core/SVGNames.h"
 #include "core/dom/Document.h"
 #include "core/dom/ElementRegistrationOptions.h"
 #include "core/dom/custom/V0CustomElementDefinition.h"
 #include "core/dom/custom/V0CustomElementDescriptor.h"
 #include "core/dom/custom/V0CustomElementException.h"
 #include "core/dom/custom/V0CustomElementProcessingStack.h"
+#include "core/frame/UseCounter.h"
 #include "wtf/Assertions.h"
 
 namespace blink {
 
 static void constructCustomElement(const v8::FunctionCallbackInfo<v8::Value>&);
 
 V0CustomElementConstructorBuilder::V0CustomElementConstructorBuilder(
     ScriptState* scriptState,
     const ElementRegistrationOptions& options)
     : m_scriptState(scriptState), m_options(options) {
@@ skipping 286 matching lines @@
       scriptState, data, V8HiddenValue::customElementType(isolate));
   TOSTRING_VOID(V8StringResource<>, type, maybeType);
 
   ExceptionState exceptionState(
       info.GetIsolate(), ExceptionState::ConstructionContext, "CustomElement");
   V0CustomElementProcessingStack::CallbackDeliveryScope deliveryScope;
   Element* element = document->createElementNS(
       namespaceURI, tagName,
       StringOrDictionary::fromString(maybeType->IsNull() ? nullAtom : type),
       exceptionState);
+  if (element) {
+    UseCounter::count(document, UseCounter::V0CustomElementsConstruct);
+  }
   v8SetReturnValueFast(info, element, document);
 }
 
 }  // namespace blink