Oilpan: Prepare moving AXObject to heap

Source/modules/accessibility/AXScrollView.cpp

 /*
  * Copyright (C) 2011 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 25 matching lines @@
 
 AXScrollView::AXScrollView(FrameView* view, AXObjectCacheImpl& axObjectCache)
     : AXObject(axObjectCache)
     , m_scrollView(view)
     , m_childrenDirty(false)
 {
 }
 
 AXScrollView::~AXScrollView()
 {
-    ASSERT(isDetached());
+    ASSERT(!m_scrollView);
 }
 
 void AXScrollView::detach()
 {
     AXObject::detach();
-    m_scrollView = 0;
+    m_scrollView = nullptr;
 }
 
-PassRefPtr<AXScrollView> AXScrollView::create(FrameView* view, AXObjectCacheImpl& axObjectCache)
+PassRefPtrWillBeRawPtr<AXScrollView> AXScrollView::create(FrameView* view, AXObjectCacheImpl& axObjectCache)
 {
-    return adoptRef(new AXScrollView(view, axObjectCache));
+    return adoptRefWillBeNoop(new AXScrollView(view, axObjectCache));
 }
 
 AXObject* AXScrollView::scrollBar(AccessibilityOrientation orientation)
 {
     updateScrollbars();
 
     switch (orientation) {
     case AccessibilityOrientationVertical:
         return m_verticalScrollbar ? m_verticalScrollbar.get() : 0;
     case AccessibilityOrientationHorizontal:
@@ skipping 178 matching lines @@
         return axObjectCache().get(owner);
 
     return axObjectCache().get(m_scrollView->frame().pagePopupOwner());
 }
 
 ScrollableArea* AXScrollView::getScrollableAreaIfScrollable() const
 {
     return m_scrollView;
 }
 
+DEFINE_TRACE(AXScrollView)
+{
+    visitor->trace(m_scrollView);
+    visitor->trace(m_horizontalScrollbar);
+    visitor->trace(m_verticalScrollbar);
+    AXObject::trace(visitor);
+}
+
 } // namespace blink