Oilpan: Prepare to move RenderObject and RenderObjectChildList to Oilpan heap.

Source/core/rendering/RenderObjectChildList.h

 /*
  * 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
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``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 COMPUTER, INC. OR
  * 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
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  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef RenderObjectChildList_h
 #define RenderObjectChildList_h
 
+#include "platform/heap/Handle.h"
 #include "wtf/Forward.h"
 
 namespace blink {
 
 class RenderObject;
 
 class RenderObjectChildList {
+    DISALLOW_ALLOCATION();
 public:
     RenderObjectChildList()
-        : m_firstChild(0)
-        , m_lastChild(0)
+        : m_firstChild(nullptr)
+        , m_lastChild(nullptr)
     {
     }
+    void trace(Visitor*);
 
-    RenderObject* firstChild() const { return m_firstChild; }
-    RenderObject* lastChild() const { return m_lastChild; }
+    RenderObject* firstChild() const { return m_firstChild.get(); }
+    RenderObject* lastChild() const { return m_lastChild.get(); }
 
     // FIXME: Temporary while RenderBox still exists. Eventually this will just happen during insert/append/remove methods on the child list, and nobody
     // will need to manipulate firstChild or lastChild directly.
     void setFirstChild(RenderObject* child) { m_firstChild = child; }
     void setLastChild(RenderObject* child) { m_lastChild = child; }
 
     void destroyLeftoverChildren();
 
     RenderObject* removeChildNode(RenderObject* owner, RenderObject*, bool notifyRenderer = true);
     void insertChildNode(RenderObject* owner, RenderObject* newChild, RenderObject* beforeChild, bool notifyRenderer = true);
     void appendChildNode(RenderObject* owner, RenderObject* newChild, bool notifyRenderer = true)
     {
         insertChildNode(owner, newChild, 0, notifyRenderer);
     }
 
 private:
-    RenderObject* m_firstChild;
-    RenderObject* m_lastChild;
+    RawPtrWillBeMember<RenderObject> m_firstChild;
+    RawPtrWillBeMember<RenderObject> m_lastChild;
 };
 
 } // namespace blink
 
 #endif // RenderObjectChildList_h