Add live region root to the cached properties of an AXObject.

Source/core/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 436 matching lines @@
     virtual bool supportsARIADropping() const { return false; }
     virtual bool supportsARIAFlowTo() const { return false; }
     virtual bool supportsARIAOwns() const { return false; }
     bool supportsRangeValue() const;
 
     // ARIA trees.
     // Used by an ARIA tree to get all its rows.
     void ariaTreeRows(AccessibilityChildrenVector&);
 
     // ARIA live-region features.
-    bool supportsARIALiveRegion() const;
-    virtual const AtomicString& ariaLiveRegionStatus() const { return nullAtom; }
-    virtual const AtomicString& ariaLiveRegionRelevant() const { return nullAtom; }
-    virtual bool ariaLiveRegionAtomic() const { return false; }
-    virtual bool ariaLiveRegionBusy() const { return false; }
+    bool isLiveRegion() const;
+    const AXObject* liveRegionRoot() const;
+    virtual const AtomicString& liveRegionStatus() const { return nullAtom; }
+    virtual const AtomicString& liveRegionRelevant() const { return nullAtom; }
+    virtual bool liveRegionAtomic() const { return false; }
+    virtual bool liveRegionBusy() const { return false; }
+
+    const AtomicString& containerLiveRegionStatus() const;
+    const AtomicString& containerLiveRegionRelevant() const;
+    bool containerLiveRegionAtomic() const;
+    bool containerLiveRegionBusy() const;
 
     // Accessibility Text.
     virtual String textUnderElement() const { return String(); }
 
     // Accessibility Text - (To be deprecated).
     virtual String accessibilityDescription() const { return String(); }
     virtual String title() const { return String(); }
     virtual String helpText() const { return String(); }
 
     // Location and click point in frame-relative coordinates.
@@ skipping 101 matching lines @@
     virtual ScrollableArea* getScrollableAreaIfScrollable() const { return 0; }
     virtual void scrollTo(const IntPoint&) const { }
 
     AccessibilityRole buttonRoleType() const;
 
     bool allowsTextRanges() const { return isTextControl(); }
     unsigned getLengthForTextRange() const { return text().length(); }
 
     bool m_detached;
 
-private:
     // 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;
+    mutable const AXObject* m_cachedLiveRegionRoot;
 
+    // Updates the cached attribute values. This may be recursive, so to prevent deadlocks,
+    // functions called here may only search up the tree (ancestors), not down.
     void updateCachedAttributeValuesIfNeeded() const;
 };
 
 #define DEFINE_AX_OBJECT_TYPE_CASTS(thisType, predicate) \
     DEFINE_TYPE_CASTS(thisType, AXObject, object, object->predicate, object.predicate)
 
 } // namespace blink
 
 #endif // AXObject_h