Reland of Uses the activedescendant_changed event received from Blink to fire the right focus event

third_party/WebKit/Source/modules/accessibility/AXListBox.cpp

Index: third_party/WebKit/Source/modules/accessibility/AXListBox.cpp
diff --git a/third_party/WebKit/Source/modules/accessibility/AXListBox.cpp b/third_party/WebKit/Source/modules/accessibility/AXListBox.cpp
index 76929b23c305c37bc643321250fe1d15bf51d531..746e12feef98d5777d6ddb7d14afc369a268c1ae 100644
--- a/third_party/WebKit/Source/modules/accessibility/AXListBox.cpp
+++ b/third_party/WebKit/Source/modules/accessibility/AXListBox.cpp
@@ -61,7 +61,7 @@
     return ListBoxRole;
 }
 
-AXObject* AXListBox::activeDescendant() const
+AXObject* AXListBox::activeDescendant()
 {
     if (!isHTMLSelectElement(getNode()))
         return nullptr;
@@ -90,12 +90,7 @@
     if (!select->focused())
         return;
 
-    if (m_activeIndex >= 0 && m_activeIndex < static_cast<int>(select->length())) {
-        HTMLOptionElement* option = select->item(m_activeIndex);
-        axObjectCache().postNotification(option, AXObjectCacheImpl::AXFocusedUIElementChanged);
-    } else {
-        axObjectCache().postNotification(this, AXObjectCacheImpl::AXFocusedUIElementChanged);
-    }
+    axObjectCache().postNotification(this, AXObjectCacheImpl::AXActiveDescendantChanged);
 }
 
 } // namespace blink