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 e45fb1af30b130c1e9972ef923cfa00d3b4aae1c..fc6b313eef75d9155386937395e1acef2fdc2aca 100644
--- a/third_party/WebKit/Source/modules/accessibility/AXObject.h
+++ b/third_party/WebKit/Source/modules/accessibility/AXObject.h
@@ -646,6 +646,7 @@ public:
     void setLastKnownIsIgnoredValue(bool);
     bool hasInheritedPresentationalRole() const;
     bool isPresentationalChild() const;
+    bool ancestorExposesActiveDescendant() const;

[dmazzoni, 2016/04/05 05:37:22]

This needs to be cached, check the other cached attributes in AXObject and how
they work. The cached values are reset whenever the tree changes in any way so
it's safe to cache. It saves us time when we scan the whole tree because we
don't have to keep walking up the ancestors of every node.

 
     //
     // Accessible name calculation
@@ -740,7 +741,7 @@ 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 { }
@@ -757,7 +758,7 @@ 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; }