Add `privacy.network.webRTCNonProxiedUdpTransportEnabled` to extensions API

chrome/test/data/extensions/api_test/preference/standard/test.js

 // Copyright (c) 2012 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.
 
 // Preferences API test
 // Run with browser_tests --gtest_filter=ExtensionApiTest.PreferenceApi
 
 var preferences_to_test = [
   {
     root: chrome.privacy.network,
     preferences: [
       'networkPredictionEnabled',
-      'webRTCMultipleRoutesEnabled'
+      'webRTCMultipleRoutesEnabled',
+      'webRTCNonProxiedUdpTransportEnabled'
     ]
   },
   {
     root: chrome.privacy.websites,
     preferences: [
       'thirdPartyCookiesAllowed',
       'hyperlinkAuditingEnabled',
       'referrersEnabled',
       'protectedContentEnabled'
     ]
@@ skipping 10 matching lines @@
       'searchSuggestEnabled',
       'spellingServiceEnabled',
       'translationServiceEnabled'
     ]
   },
 ];
 
 // Some preferences are only present on certain platforms or are hidden
 // behind flags and might not be present when this test runs.
 var possibly_missing_preferences = new Set([
-  'protectedContentEnabled',    // Windows/ChromeOS only
-  'webRTCMultipleRoutesEnabled' // requires ENABLE_WEBRTC=1
+  'protectedContentEnabled',             // Windows/ChromeOS only
+  'webRTCMultipleRoutesEnabled',         // requires ENABLE_WEBRTC=1
+  'webRTCNonProxiedUdpTransportEnabled'  // requires ENABLE_WEBRTC=1
 ]);
 
 function expect(expected, message) {
   return chrome.test.callbackPass(function(value) {
     chrome.test.assertEq(expected, value, message);
   });
 }
 
 function expectFalse(pref) {
   return expect({
@@ skipping 23 matching lines @@
           prefGetter.bind(preferences_to_test[i].root));
     }
   },
   function setGlobals() {
     for (var i = 0; i < preferences_to_test.length; i++) {
       preferences_to_test[i].preferences.forEach(
           prefSetter.bind(preferences_to_test[i].root));
     }
   }
 ]);