Oilpan: Prepare moving AXObject to heap

Source/modules/accessibility/AXScrollView.h

Index: Source/modules/accessibility/AXScrollView.h
diff --git a/Source/modules/accessibility/AXScrollView.h b/Source/modules/accessibility/AXScrollView.h
index b94cd28c6744bd6ea03757c5d45218064f70aebd..5776f602832e74934cdc78c33e2f1e504f7b4df5 100644
--- a/Source/modules/accessibility/AXScrollView.h
+++ b/Source/modules/accessibility/AXScrollView.h
@@ -37,11 +37,12 @@ class FrameView;
 
 class AXScrollView final : public AXObject {
 public:
-    static PassRefPtr<AXScrollView> create(FrameView*, AXObjectCacheImpl*);
+    static PassRefPtrWillBeRawPtr<AXScrollView> create(FrameView*, AXObjectCacheImpl*);
     virtual AccessibilityRole roleValue() const override { return ScrollAreaRole; }
     FrameView* scrollView() const { return m_scrollView; }
 
     virtual ~AXScrollView();
+    DECLARE_VIRTUAL_TRACE();
     virtual void detach() override;
 
 protected:
@@ -86,9 +87,9 @@ private:
     // as part of moving the AX objects to the heap. Temporarily using
     // a Persistent risks creating a FrameView leak, and brings no
     // real benefits overall.
-    FrameView* m_scrollView;
-    RefPtr<AXObject> m_horizontalScrollbar;
-    RefPtr<AXObject> m_verticalScrollbar;
+    RawPtrWillBeWeakMember<FrameView> m_scrollView;
+    RefPtrWillBeMember<AXObject> m_horizontalScrollbar;
+    RefPtrWillBeMember<AXObject> m_verticalScrollbar;
     bool m_childrenDirty;
 };