Support aria-grabbed attribute.

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 243 matching lines @@
     AccessibilityTextDirectionTopToBottom,
     AccessibilityTextDirectionBottomToTop
 };
 
 enum AccessibilityExpanded {
     ExpandedUndefined = 0,
     ExpandedCollapsed,
     ExpandedExpanded,
 };
 
+enum AccessibilityOptionalBool {
+    OptionalBoolUndefined = 0,
+    OptionalBoolTrue,
+    OptionalBoolFalse
+};
+
 class AXObject : public RefCounted<AXObject> {
 public:
     typedef Vector<RefPtr<AXObject> > AccessibilityChildrenVector;
 
     struct PlainTextRange {
 
         unsigned start;
         unsigned length;
 
         PlainTextRange()
@@ skipping 167 matching lines @@
     virtual void ariaControlsElements(AccessibilityChildrenVector&) const { }
     virtual void ariaDescribedbyElements(AccessibilityChildrenVector& describedby) const { };
     virtual void ariaLabelledbyElements(AccessibilityChildrenVector& labelledby) const { };
     virtual void ariaOwnsElements(AccessibilityChildrenVector& owns) const { };
     virtual bool ariaHasPopup() const { return false; }
     bool ariaIsMultiline() const;
     virtual String ariaLabeledByAttribute() const { return String(); }
     bool ariaPressedIsPresent() const;
     virtual AccessibilityRole ariaRoleAttribute() const { return UnknownRole; }
     virtual bool ariaRoleHasPresentationalChildren() const { return false; }
-    virtual bool isARIAGrabbed() { return false; }
+    virtual AccessibilityOptionalBool isAriaGrabbed() const { return OptionalBoolUndefined; }
     virtual bool isPresentationalChildOfAriaRole() const { return false; }
     virtual bool shouldFocusActiveDescendant() const { return false; }
     bool supportsARIAAttributes() const;
     virtual bool supportsARIADragging() const { return false; }
     virtual bool supportsARIADropping() const { return false; }
     virtual bool supportsARIAFlowTo() const { return false; }
     virtual bool supportsARIAOwns() const { return false; }
     bool supportsRangeValue() const;
 
     // ARIA trees.
@@ skipping 148 matching lines @@
     // 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