Oilpan: have History on the heap by default.

Source/core/events/PopStateEvent.cpp

 /*
  * Copyright (C) 2009 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
@@ skipping 27 matching lines @@
     , m_history(nullptr)
 {
 }
 
 PopStateEvent::PopStateEvent(const AtomicString& type, const PopStateEventInit& initializer)
     : Event(type, initializer)
     , m_history(nullptr)
 {
 }
 
-PopStateEvent::PopStateEvent(PassRefPtr<SerializedScriptValue> serializedState, PassRefPtrWillBeRawPtr<History> history)
+PopStateEvent::PopStateEvent(PassRefPtr<SerializedScriptValue> serializedState, History* history)
     : Event(EventTypeNames::popstate, false, true)
     , m_serializedState(serializedState)
     , m_history(history)
 {
 }
 
 PopStateEvent::~PopStateEvent()
 {
 }
 
 PassRefPtrWillBeRawPtr<PopStateEvent> PopStateEvent::create()
 {
     return adoptRefWillBeNoop(new PopStateEvent);
 }
 
-PassRefPtrWillBeRawPtr<PopStateEvent> PopStateEvent::create(PassRefPtr<SerializedScriptValue> serializedState, PassRefPtrWillBeRawPtr<History> history)
+PassRefPtrWillBeRawPtr<PopStateEvent> PopStateEvent::create(PassRefPtr<SerializedScriptValue> serializedState, History* history)
 {
     return adoptRefWillBeNoop(new PopStateEvent(serializedState, history));
 }
 
 PassRefPtrWillBeRawPtr<PopStateEvent> PopStateEvent::create(const AtomicString& type, const PopStateEventInit& initializer)
 {
     return adoptRefWillBeNoop(new PopStateEvent(type, initializer));
 }
 
 const AtomicString& PopStateEvent::interfaceName() const
 {
     return EventNames::PopStateEvent;
 }
 
 DEFINE_TRACE(PopStateEvent)
 {
     visitor->trace(m_history);
     Event::trace(visitor);
 }
 
 } // namespace blink