Oilpan: Prepare moving AXObject to heap

Source/modules/accessibility/AXImageMapLink.cpp

Index: Source/modules/accessibility/AXImageMapLink.cpp
diff --git a/Source/modules/accessibility/AXImageMapLink.cpp b/Source/modules/accessibility/AXImageMapLink.cpp
index 1d26401d4755a2eb79ab61d194e7432ed4608edc..443f35d6709a7c946b7c3c0c265ba89e29189f62 100644
--- a/Source/modules/accessibility/AXImageMapLink.cpp
+++ b/Source/modules/accessibility/AXImageMapLink.cpp
@@ -45,6 +45,15 @@ AXImageMapLink::AXImageMapLink(AXObjectCacheImpl& axObjectCache)
 
 AXImageMapLink::~AXImageMapLink()
 {
+    ASSERT(!m_areaElement);
+    ASSERT(!m_mapElement);
+}
+
+void AXImageMapLink::detach()
+{
+    AXMockObject::detach();
+    m_areaElement = nullptr;
+    m_mapElement = nullptr;
 }
 
 void AXImageMapLink::detachFromParent()
@@ -54,9 +63,9 @@ void AXImageMapLink::detachFromParent()
     m_mapElement = nullptr;
 }
 
-PassRefPtr<AXImageMapLink> AXImageMapLink::create(AXObjectCacheImpl& axObjectCache)
+PassRefPtrWillBeRawPtr<AXImageMapLink> AXImageMapLink::create(AXObjectCacheImpl& axObjectCache)
 {
-    return adoptRef(new AXImageMapLink(axObjectCache));
+    return adoptRefWillBeNoop(new AXImageMapLink(axObjectCache));
 }
 
 AXObject* AXImageMapLink::computeParent() const
@@ -141,4 +150,11 @@ LayoutRect AXImageMapLink::elementRect() const
     return m_areaElement->computeRect(layoutObject);
 }
 
+DEFINE_TRACE(AXImageMapLink)
+{
+    visitor->trace(m_areaElement);
+    visitor->trace(m_mapElement);
+    AXMockObject::trace(visitor);
+}
+
 } // namespace blink