Refactor: Clear m_axObjectCache when AXObject detaches

Source/modules/accessibility/AXObject.h

 /*
  * Copyright (C) 2008, 2009, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nuanti Ltd.
  *
  * 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.
@@ skipping 356 matching lines @@
 
         PlainTextRange(unsigned s, unsigned l)
             : start(s)
             , length(l)
         { }
 
         bool isNull() const { return !start && !length; }
     };
 
 protected:
-    AXObject(AXObjectCacheImpl*);
+    AXObject(AXObjectCacheImpl&);
 
 public:
     virtual ~AXObject();
 
     // After constructing an AXObject, it must be given a
     // unique ID, then added to AXObjectCacheImpl, and finally init() must
     // be called last.
     void setAXObjectID(AXID axObjectID) { m_id = axObjectID; }
     virtual void init() { }
 
     // When the corresponding WebCore object that this AXObject
     // wraps is deleted, it must be detached.
     virtual void detach();
     virtual bool isDetached() const;
 
     // If the parent of this object is known, this can be faster than using computeParent().
     virtual void setParent(AXObject* parent) { m_parent = parent; }
 
     // The AXObjectCacheImpl that owns this object, and its unique ID within this cache.
-    AXObjectCacheImpl* axObjectCache() const { return m_axObjectCache; }
+    AXObjectCacheImpl& axObjectCache() const
+    {
+        ASSERT(m_axObjectCache);
+        return *m_axObjectCache;
+    }
 
     AXID axObjectID() const { return m_id; }
 
     // Determine subclass type.
     virtual bool isAXNodeObject() const { return false; }
     virtual bool isAXLayoutObject() const { return false; }
     virtual bool isAXListBox() const { return false; }
     virtual bool isAXListBoxOption() const { return false; }
     virtual bool isAXScrollbar() const { return false; }
     virtual bool isAXScrollView() const { return false; }
@@ skipping 356 matching lines @@
     LayoutRect m_explicitElementRect;
 
     virtual const AXObject* inheritsPresentationalRoleFrom() const { return 0; }
 
     bool nameFromContents() const;
 
     AccessibilityRole buttonRoleType() const;
 
     unsigned getLengthForTextRange() const { return text().length(); }
 
-    bool m_detached;
-
     mutable AXObject* m_parent;
 
     // The following cached attribute values (the ones starting with m_cached*)
     // are only valid if m_lastModificationCount matches AXObjectCacheImpl::modificationCount().
     mutable int m_lastModificationCount;
     mutable bool m_cachedIsIgnored : 1;
     mutable bool m_cachedIsInertOrAriaHidden : 1;
     mutable bool m_cachedIsDescendantOfLeafNode : 1;
     mutable bool m_cachedIsDescendantOfDisabledNode : 1;
     mutable bool m_cachedHasInheritedPresentationalRole : 1;
@@ skipping 10 matching lines @@
     static bool includesARIAWidgetRole(const String&);
     static bool hasInteractiveARIAAttribute(const Element&);
 };
 
 #define DEFINE_AX_OBJECT_TYPE_CASTS(thisType, predicate) \
     DEFINE_TYPE_CASTS(thisType, AXObject, object, object->predicate, object.predicate)
 
 } // namespace blink
 
 #endif // AXObject_h