MD Settings: compose a <paper-radio-button> instead of wrapping one in <controlled-radio-button>

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],
+  behaviors: [
+    PrefControlBehavior,
+    Polymer.IronA11yKeysBehavior,
+  ],
 
   properties: {
-    label: String,
+    checked: {
+      type: Boolean,
+      reflectToAttribute: true,
+      observer: 'checkedChanged_',
+    },
+
+    label: {
+      type: String,
+      value: '',  // Allows the hidden$= binding to run without being set.
+    },
 
     name: {
       type: String,
       notify: true,
     },
 
     /** @private */
     controlled_: {
       type: Boolean,
       computed: 'computeControlled_(pref.*)',
       reflectToAttribute: true,
     },
+
+    /** @private */
+    pressed_: Boolean,
+  },
+
+  hostAttributes: {
+    role: 'radio',
+    tabindex: 0,
   },
 
   listeners: {
-    'focus': 'onFocus_',
+    'blur': 'updatePressed_',
+    'down': 'updatePressed_',
+    'focus': 'updatePressed_',
+    'tap': 'onTap_',
+    'up': 'updatePressed_',
+  },
+
+  keyBindings: {
+    // This is mainly for screenreaders, which can perform actions on things
+    // that aren't focused (only focused things get synthetic click/tap events).
+    'enter:keyup': 'click',
+    'space:keyup': 'click',
+  },
+
+  /** @private */
+  checkedChanged_: function() {
+    this.setAttribute('aria-checked', this.checked ? 'true' : 'false');
   },
 
   /**
    * @return {boolean} Whether the button is disabled.
    * @private
    */
   computeControlled_: function() {
     return this.pref.enforcement == chrome.settingsPrivate.Enforcement.ENFORCED;
   },
 
@@ skipping 11 matching lines @@
   /**
    * @param {!Event} e
    * @private
    */
   onIndicatorTap_: function(e) {
     // 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();
+  /** @private */
+  onTap_: function() {
+    if (!this.controlled_)
+      this.checked = true;
+  },
+
+  /**
+   * @param {!Event} e
+   * @private
+   */
+  updatePressed_: function(e) {
+    this.pressed_ = ['down', 'focus'].includes(e.type);
   },
 });