Oilpan: Remove guardRef and guardDeref from TreeScope.

Source/core/accessibility/AXObjectCache.h

 /*
  * Copyright (C) 2003, 2006, 2007, 2008, 2009, 2010, 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 90 matching lines @@
     AXObject* get(Widget*);
     AXObject* get(Node*);
     AXObject* get(AbstractInlineTextBox*);
 
     void remove(RenderObject*);
     void remove(Node*);
     void remove(Widget*);
     void remove(AbstractInlineTextBox*);
     void remove(AXID);
 
+    void clearWeakMembers(Visitor*);
+
     void detachWrapper(AXObject*);
     void attachWrapper(AXObject*);
     void childrenChanged(Node*);
     void childrenChanged(RenderObject*);
     void childrenChanged(AXObject*);
     void checkedStateChanged(Node*);
     void selectedChildrenChanged(Node*);
     void selectedChildrenChanged(RenderObject*);
     void selectionChanged(Node*);
     // Called by a node when text or a text equivalent (e.g. alt) attribute is changed.
@@ skipping 80 matching lines @@
     void postPlatformNotification(AXObject*, AXNotification);
     void textChanged(AXObject*);
     void labelChanged(Element*);
 
     // This is a weak reference cache for knowing if Nodes used by TextMarkers are valid.
     void setNodeInUse(Node* n) { m_textMarkerNodes.add(n); }
     void removeNodeForUse(Node* n) { m_textMarkerNodes.remove(n); }
     bool isNodeInUse(Node* n) { return m_textMarkerNodes.contains(n); }
 
 private:
     Document& m_document;

[haraken, 2014/04/25 05:21:42]

Now that Document is on-heap and can outlive AXObjectCache. Don't you need to
change this a raw pointer and clear it when the Document dies?

[Mads Ager (chromium), 2014/04/25 10:58:25]

The AXObjectCache has not been moved to the heap yet. The AXObjectCache is in an
OwnPtr on the Document, so when the Document is destructed the AXObjectCache is
destructed as well. So they still die together.

When we move AXObjectCache to the oilpan heap the AXObjectCache and the Document
need to have Members to eachother so that they die in the same round of GC. So
this will become a Member to the Document.

     HashMap<AXID, RefPtr<AXObject> > m_objects;
     HashMap<RenderObject*, AXID> m_renderObjectMapping;
     HashMap<Widget*, AXID> m_widgetObjectMapping;
     HashMap<Node*, AXID> m_nodeObjectMapping;
     HashMap<AbstractInlineTextBox*, AXID> m_inlineTextBoxObjectMapping;
     HashSet<Node*> m_textMarkerNodes;
     OwnPtr<AXComputedObjectAttributeCache> m_computedObjectAttributeCache;
     static bool gAccessibilityEnabled;
     static bool gInlineTextBoxAccessibility;
 
     HashSet<AXID> m_idsInUse;
 
     Timer<AXObjectCache> m_notificationPostTimer;
     Vector<pair<RefPtr<AXObject>, AXNotification> > m_notificationsToPost;
     void notificationPostTimerFired(Timer<AXObjectCache>*);
 
     static AXObject* focusedImageMapUIElement(HTMLAreaElement*);
 
     AXID getAXID(AXObject*);
 };
 
 bool nodeHasRole(Node*, const String& role);
 // This will let you know if aria-hidden was explicitly set to false.
 bool isNodeAriaVisible(Node*);
 
 }
 
 #endif