Various fixes for aria-activedescendant.

third_party/WebKit/Source/modules/accessibility/AXObject.h

Index: third_party/WebKit/Source/modules/accessibility/AXObject.h
diff --git a/third_party/WebKit/Source/modules/accessibility/AXObject.h b/third_party/WebKit/Source/modules/accessibility/AXObject.h
index 6b72a41b323cc78f507b10456c174ccb274cb212..6cc68f4bfc659ef37331554fcbf18e82c7a6385a 100644
--- a/third_party/WebKit/Source/modules/accessibility/AXObject.h
+++ b/third_party/WebKit/Source/modules/accessibility/AXObject.h
@@ -648,6 +648,8 @@ public:
     void setLastKnownIsIgnoredValue(bool);
     bool hasInheritedPresentationalRole() const;
     bool isPresentationalChild() const;
+    bool ancestorExposesActiveDescendant() const;
+    bool computeAncestorExposesActiveDescendant() const;
 
     //
     // Accessible name calculation
@@ -742,7 +744,7 @@ public:
     virtual String stringValue() const { return String(); }
 
     // ARIA attributes.
-    virtual AXObject* activeDescendant() const { return 0; }
+    virtual AXObject* activeDescendant() const { return nullptr; }
     virtual String ariaAutoComplete() const { return String(); }
     virtual String ariaDescribedByAttribute() const { return String(); }
     virtual void ariaFlowToElements(AXObjectVector&) const { }
@@ -759,7 +761,7 @@ public:
     virtual AccessibilityRole ariaRoleAttribute() const { return UnknownRole; }
     virtual bool ariaRoleHasPresentationalChildren() const { return false; }
     virtual AXObject* ancestorForWhichThisIsAPresentationalChild() const { return 0; }
-    virtual bool shouldFocusActiveDescendant() const { return false; }
+    bool supportsActiveDescendant() const;
     bool supportsARIAAttributes() const;
     virtual bool supportsARIADragging() const { return false; }
     virtual bool supportsARIADropping() const { return false; }
@@ -937,6 +939,7 @@ protected:
     mutable bool m_cachedIsDescendantOfDisabledNode : 1;
     mutable bool m_cachedHasInheritedPresentationalRole : 1;
     mutable bool m_cachedIsPresentationalChild : 1;
+    mutable bool m_cachedAncestorExposesActiveDescendant : 1;
     mutable Member<const AXObject> m_cachedLiveRegionRoot;
 
     Member<AXObjectCacheImpl> m_axObjectCache;