EventSender<T> singletons are better off on the Oilpan heap.

third_party/WebKit/Source/core/events/EventSender.h

 /*
  * Copyright (C) 2012 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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  */
 
 #ifndef EventSender_h
 #define EventSender_h
 
 #include "platform/Timer.h"
+#include "platform/heap/Handle.h"
 #include "wtf/Vector.h"
 #include "wtf/text/AtomicString.h"
 
 namespace blink {
 
-template<typename T> class EventSender {
-    WTF_MAKE_NONCOPYABLE(EventSender); USING_FAST_MALLOC(EventSender);
+template<typename T>
+class EventSender final : public NoBaseWillBeGarbageCollectedFinalized<EventSender<T>> {
+    WTF_MAKE_NONCOPYABLE(EventSender);
+    USING_FAST_MALLOC_WILL_BE_REMOVED(EventSender);
 public:
-    explicit EventSender(const AtomicString& eventType);
+    static PassOwnPtrWillBeRawPtr<EventSender> create(const AtomicString& eventType)
+    {
+        return adoptPtrWillBeNoop(new EventSender(eventType));
+    }
 
     const AtomicString& eventType() const { return m_eventType; }
     void dispatchEventSoon(T*);
     void cancelEvent(T*);
     void dispatchPendingEvents();
 
 #if ENABLE(ASSERT)
     bool hasPendingEvents(T* sender) const
     {
         return m_dispatchSoonList.find(sender) != kNotFound || m_dispatchingList.find(sender) != kNotFound;
     }
 #endif
 
+    DEFINE_INLINE_TRACE()
+    {
+        visitor->trace(m_dispatchSoonList);
+        visitor->trace(m_dispatchingList);
+    }
+
 private:
+    explicit EventSender(const AtomicString& eventType);
+
     void timerFired(Timer<EventSender<T>>*) { dispatchPendingEvents(); }
 
     AtomicString m_eventType;
     Timer<EventSender<T>> m_timer;
-    WillBePersistentHeapVector<RawPtrWillBeMember<T>> m_dispatchSoonList;
-    WillBePersistentHeapVector<RawPtrWillBeMember<T>> m_dispatchingList;
+    WillBeHeapVector<RawPtrWillBeMember<T>> m_dispatchSoonList;
+    WillBeHeapVector<RawPtrWillBeMember<T>> m_dispatchingList;
 };
 
 template<typename T> EventSender<T>::EventSender(const AtomicString& eventType)
     : m_eventType(eventType)
     , m_timer(this, &EventSender::timerFired)
 {
 }
 
 template<typename T> void EventSender<T>::dispatchEventSoon(T* sender)
 {
@@ skipping 35 matching lines @@
             m_dispatchingList[i] = nullptr;
             sender->dispatchPendingEvent(this);
         }
     }
     m_dispatchingList.clear();
 }
 
 } // namespace blink
 
 #endif // EventSender_h