Only process checked state changed for specific roles.

chrome/browser/resources/chromeos/chromevox/cvox2/background/automation_predicate.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @fileoverview ChromeVox predicates for the automation extension API.
  */
 
 goog.provide('AutomationPredicate');
 goog.provide('AutomationPredicate.Binary');
@@ skipping 271 matching lines @@
 
   // Ignore some roles.
   return AutomationPredicate.leaf(node) &&
       (node.role == RoleType.client ||
        node.role == RoleType.div ||
        node.role == RoleType.group ||
        node.role == RoleType.image ||
        node.role == RoleType.staticText);
 };
 
+
+/**
+ * Returns if the node has a meaningful checked state.
+ * @param {!AutomationNode} node
+ * @return {boolean}
+ */
+AutomationPredicate.checkable = function(node) {
+  return node.role == RoleType.checkBox ||
+      node.role == RoleType.radioButton ||
+      node.role == RoleType.menuItemCheckBox ||
+      node.role == RoleType.menuItemRadio;
+};
+
 });  // goog.scope