Add virtual destructors to IntersectionObserverCallback

third_party/WebKit/Source/core/dom/IntersectionObserver.cpp

 // 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.
 
 #include "core/dom/IntersectionObserver.h"
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "core/css/parser/CSSParserTokenRange.h"
 #include "core/css/parser/CSSTokenizer.h"
 #include "core/dom/ExceptionCode.h"
@@ skipping 134 matching lines @@
         m_bottomMargin = rootMargin[2];
         m_leftMargin = rootMargin[3];
         break;
     default:
         ASSERT_NOT_REACHED();
         break;
     }
     root.document().ensureIntersectionObserverController().addTrackedObserver(*this);
 }
 
+IntersectionObserver::~IntersectionObserver()
+{
+}
+
 LayoutObject* IntersectionObserver::rootLayoutObject() const
 {
     Node* rootNode = root();
     if (rootNode->isDocumentNode())
         return toDocument(rootNode)->layoutView();
     return toElement(rootNode)->layoutObject();
 }
 
 bool IntersectionObserver::isDescendantOfRoot(const Element* target) const
 {
@@ skipping 178 matching lines @@
 
 DEFINE_TRACE(IntersectionObserver)
 {
     visitor->trace(m_callback);
     visitor->trace(m_root);
     visitor->trace(m_observations);
     visitor->trace(m_entries);
 }
 
 } // namespace blink