MD Settings: add an aria-label to control indicators (often policy)

chrome/browser/resources/settings/controls/controlled_radio_button.js

 // Copyright 2016 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.
 
 Polymer({
   is: 'controlled-radio-button',
 
   behaviors: [PrefControlBehavior],
 
   properties: {
+    label: String,
+
     name: {
       type: String,
       notify: true,
     },
 
     /** @private */
     controlled_: {
       type: Boolean,
       computed: 'computeControlled_(pref.*)',
       reflectToAttribute: true,
@@ skipping 31 matching lines @@
     // Disallow <controlled-radio-button on-tap="..."> when controlled.
     e.preventDefault();
     e.stopPropagation();
   },
 
   /** Focuses the internal radio button when the row is selected. */
   onFocus_: function() {
     this.$.radioButton.focus();
   },
 });