1 files changed, 17 insertions, 3 deletions
diff --git a/chromium/ui/webui/resources/js/cr/ui/tree.js b/chromium/ui/webui/resources/js/cr/ui/tree.js
index 3c12715d55d..04f978ebf72 100644
--- a/chromium/ui/webui/resources/js/cr/ui/tree.js
+++ b/chromium/ui/webui/resources/js/cr/ui/tree.js
@@ -201,9 +201,13 @@ cr.define('cr.ui', function() {
         if (oldSelectedItem)
           oldSelectedItem.selected = false;
 
-        if (item)
+        if (item) {
           item.selected = true;
-
+          if (item.id)
+            this.setAttribute('aria-activedescendant', item.id);
+        } else {
+            this.removeAttribute('aria-activedescendant');
+        }
         cr.dispatchSimpleEvent(this, 'change');
       }
     },
@@ -231,6 +235,14 @@ cr.define('cr.ui', function() {
   cr.defineProperty(Tree, 'iconVisibility', cr.PropertyKind.ATTR);
 
   /**
+   * Incremental counter for an auto generated ID of the tree item. This will
+   * be incremented per element, so each element never share same ID.
+   *
+   * @type {number}
+   */
+  var treeItemAutoGeneratedIdCounter = 0;
+
+  /**
    * This is used as a blueprint for new tree item elements.
    * @type {!HTMLElement}
    */
@@ -253,7 +265,9 @@ cr.define('cr.ui', function() {
    * @extends {HTMLElement}
    */
   var TreeItem = cr.ui.define(function() {
-    return treeItemProto.cloneNode(true);
+    var treeItem = treeItemProto.cloneNode(true);
+    treeItem.id = 'tree-item-autogen-id-' + treeItemAutoGeneratedIdCounter++;
+    return treeItem;
   });
 
   TreeItem.prototype = {