Add use counters for elements used in Shadow DOM

third_party/WebKit/Source/core/html/HTMLSlotElement.cpp

 /*
  * Copyright (C) 2015 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 21 matching lines @@
 
 #include "bindings/core/v8/Microtask.h"
 #include "core/HTMLNames.h"
 #include "core/dom/NodeTraversal.h"
 #include "core/dom/StyleChangeReason.h"
 #include "core/dom/StyleEngine.h"
 #include "core/dom/shadow/ElementShadow.h"
 #include "core/dom/shadow/InsertionPoint.h"
 #include "core/dom/shadow/SlotAssignment.h"
 #include "core/events/Event.h"
+#include "core/frame/UseCounter.h"
 #include "core/html/AssignedNodesOptions.h"
 #include "core/probe/CoreProbes.h"
 
 namespace blink {
 
 using namespace HTMLNames;
 
 inline HTMLSlotElement::HTMLSlotElement(Document& document)
     : HTMLElement(slotTag, document) {
+  UseCounter::count(document, UseCounter::HTMLSlotElement);
   setHasCustomStyleCallbacks();
 }
 
 DEFINE_NODE_FACTORY(HTMLSlotElement);
 
 // static
 AtomicString HTMLSlotElement::normalizeSlotName(const AtomicString& name) {
   return (name.isNull() || name.isEmpty()) ? emptyAtom : name;
 }
 
@@ skipping 297 matching lines @@
 
 DEFINE_TRACE(HTMLSlotElement) {
   visitor->trace(m_assignedNodes);
   visitor->trace(m_distributedNodes);
   visitor->trace(m_oldDistributedNodes);
   visitor->trace(m_distributedIndices);
   HTMLElement::trace(visitor);
 }
 
 }  // namespace blink