WebUI: swap paper-dropdown-menu out for md-select.

chrome/browser/resources/md_extensions/keyboard_shortcuts.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.
 
 cr.define('extensions', function() {
   'use strict';
 
   // The UI to display and manage keyboard shortcuts set for extension commands.
   var KeyboardShortcuts = Polymer({
     is: 'extensions-keyboard-shortcuts',
 
     behaviors: [Polymer.NeonAnimatableBehavior],
 
     properties: {
       /** @type {Array<!chrome.developerPrivate.ExtensionInfo>} */
       items: Array,
+
+      /**
+       * Proxying the enum to be used easily by the html template.
+       * @private
+       */
+      CommandScope_: {
+        type: Object,
+        value: chrome.developerPrivate.CommandScope
+      },
     },
 
     ready: function() {
       /** @type {!extensions.AnimationHelper} */
       this.animationHelper = new extensions.AnimationHelper(this, this.$.main);
       this.animationHelper.setEntryAnimations([extensions.Animation.FADE_IN]);
       this.animationHelper.setExitAnimations([extensions.Animation.SCALE_DOWN]);
       this.sharedElements = {hero: this.$.main};
     },
 
@@ skipping 23 matching lines @@
      * Determines whether to disable the dropdown menu for the command's scope.
      * @param {!chrome.developerPrivate.Command} command
      * @return {boolean}
      * @private
      */
     computeScopeDisabled_: function(command) {
       return command.isExtensionAction || !command.isActive;
     },
 
     /**
-     * Returns the scope index in the dropdown menu for the command's scope.
-     * @param {chrome.developerPrivate.Command} command
-     * @return {number}
-     * @private
+     * This function exists to force trigger an update when CommandScope_
+     * becomes available.
+     * @param {string} scope
+     * @return {string}
      */
-    computeSelectedScope_: function(command) {
-      // These numbers match the indexes in the dropdown menu in the html.
-      switch (command.scope) {
-        case chrome.developerPrivate.CommandScope.CHROME:
-          return 0;
-        case chrome.developerPrivate.CommandScope.GLOBAL:
-          return 1;
-      }
-      assertNotReached();
+    triggerScopeChange_: function(scope) {
+      return scope;
     },
 
     /** @private */
     onCloseButtonClick_: function() {
       this.fire('close');
     },
+
+    /**
+     * @param {!{target: HTMLSelectElement, model: Object}} event
+     * @private
+     */
+    onScopeChanged_: function(event) {
+      event.model.set('command.scope', event.target.value);
+    },
   });
 
   return {KeyboardShortcuts: KeyboardShortcuts};
 });