Oilpan: Prepare moving AXObject to heap

Source/modules/accessibility/AXObject.cpp

Index: Source/modules/accessibility/AXObject.cpp
diff --git a/Source/modules/accessibility/AXObject.cpp b/Source/modules/accessibility/AXObject.cpp
index d32949862ce207240aef7bef12bfb99dedfe2c43..b5cfdc5d668800d8434cae771a6c59089c25a2c9 100644
--- a/Source/modules/accessibility/AXObject.cpp
+++ b/Source/modules/accessibility/AXObject.cpp
@@ -375,7 +375,7 @@ AXObject::AXObject(AXObjectCacheImpl& axObjectCache)
     , m_haveChildren(false)
     , m_role(UnknownRole)
     , m_lastKnownIsIgnoredValue(DefaultBehavior)
-    , m_parent(0)
+    , m_parent(nullptr)
     , m_lastModificationCount(-1)
     , m_cachedIsIgnored(false)
     , m_cachedIsInertOrAriaHidden(false)
@@ -383,7 +383,7 @@ AXObject::AXObject(AXObjectCacheImpl& axObjectCache)
     , m_cachedIsDescendantOfDisabledNode(false)
     , m_cachedHasInheritedPresentationalRole(false)
     , m_cachedIsPresentationalChild(false)
-    , m_cachedLiveRegionRoot(0)
+    , m_cachedLiveRegionRoot(nullptr)
     , m_axObjectCache(&axObjectCache)
 {
 }
@@ -667,9 +667,9 @@ bool AXObject::isPresentationalChild() const
     return m_cachedIsPresentationalChild;
 }
 
-String AXObject::name(AXNameFrom& nameFrom, Vector<AXObject*>& nameObjects)
+String AXObject::name(AXNameFrom& nameFrom, WillBeHeapVector<RawPtrWillBeMember<AXObject>>& nameObjects)
 {
-    HashSet<AXObject*> visited;
+    WillBeHeapHashSet<RawPtrWillBeMember<AXObject>> visited;
     return textAlternative(false, false, visited, &nameFrom, &nameObjects);
 }
 
@@ -1480,4 +1480,12 @@ const AtomicString& AXObject::internalRoleName(AccessibilityRole role)
     return internalRoleNameVector->at(role);
 }
 
+DEFINE_TRACE(AXObject)
+{
+    visitor->trace(m_children);
+    visitor->trace(m_parent);
+    visitor->trace(m_cachedLiveRegionRoot);
+    visitor->trace(m_axObjectCache);
+}
+
 } // namespace blink