Oilpan: Prepare moving AXObject to heap

Source/modules/accessibility/AXTable.h

 /*
  * Copyright (C) 2008 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
@@ skipping 26 matching lines @@
 
 class AXObjectCacheImpl;
 class AXTableCell;
 
 class MODULES_EXPORT AXTable : public AXLayoutObject {
 
 protected:
     AXTable(LayoutObject*, AXObjectCacheImpl&);
 
 public:
-    static PassRefPtr<AXTable> create(LayoutObject*, AXObjectCacheImpl&);
+    static PassRefPtrWillBeRawPtr<AXTable> create(LayoutObject*, AXObjectCacheImpl&);
     virtual ~AXTable();
+    DECLARE_VIRTUAL_TRACE();
 
     virtual void init() override final;
 
     virtual bool isAXTable() const override final;
     virtual bool isDataTable() const override final;
 
     virtual AccessibilityRole roleValue() const override final;
 
     virtual void addChildren() override;
     virtual void clearChildren() override final;
@@ skipping 17 matching lines @@
     void columnHeaders(AccessibilityChildrenVector&);
     void rowHeaders(AccessibilityChildrenVector&);
 
     // an object that contains, as children, all the objects that act as headers
     AXObject* headerContainer();
 
 protected:
     AccessibilityChildrenVector m_rows;
     AccessibilityChildrenVector m_columns;
 
-    RefPtr<AXObject> m_headerContainer;
+    RefPtrWillBeMember<AXObject> m_headerContainer;
     bool m_isAXTable;
 
     bool hasARIARole() const;
     virtual bool isTableExposableThroughAccessibility() const;
     virtual bool computeAccessibilityIsIgnored(IgnoredReasons* = nullptr) const override final;
 };
 
 DEFINE_AX_OBJECT_TYPE_CASTS(AXTable, isAXTable());
 
 } // namespace blink
 
 #endif // AXTable_h