Updated XHR API so call sites are more descriptive.

remoting/webapp/crd/js/host_controller.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.
 
 'use strict';
 
 /** @suppress {duplicate} */
 var remoting = remoting || {};
 
 /** @constructor */
@@ skipping 216 matching lines @@
     that.getClientBaseJid_(
         onClientBaseJid.bind(
             null, hostName, publicKey, privateKey, email, refreshToken),
         onStartError);
   }
 
   /**
    * @param {string} hostName
    * @param {string} publicKey
    * @param {string} privateKey
-   * @param {XMLHttpRequest} xhr
+   * @param {remoting.Xhr.Response} xhrr
    */
   function onRegistered(
-      hostName, publicKey, privateKey, xhr) {
-    var success = (xhr.status == 200);
+      hostName, publicKey, privateKey, xhrr) {
+    var success = (xhrr.status == 200);
 
     if (success) {
-      var result = base.jsonParseSafe(xhr.responseText);
+      var result = base.jsonParseSafe(xhrr.responseText);
       if ('data' in result && 'authorizationCode' in result['data']) {
         that.hostDaemonFacade_.getCredentialsFromAuthCode(
             result['data']['authorizationCode'],
             onServiceAccountCredentials.bind(
                 null, hostName, publicKey, privateKey),
             onError);
       } else {
         // No authorization code returned, use regular user credential flow.
         remoting.identity.getEmail().then(
             function(/** string */ email) {
               that.hostDaemonFacade_.getPinHash(
                   newHostId, hostPin, startHostWithHash.bind(
                       null, hostName, publicKey, privateKey,
                       email, remoting.oauth2.getRefreshToken(), email),
                   onError);
             });
       }
     } else {
-      console.log('Failed to register the host. Status: ' + xhr.status +
-                  ' response: ' + xhr.responseText);
+      console.log('Failed to register the host. Status: ' + xhrr.status +
+                  ' response: ' + xhrr.responseText);
       onError(remoting.Error.REGISTRATION_FAILED);
     }
   }
 
   /**
    * @param {string} hostName
    * @param {string} privateKey
    * @param {string} publicKey
    * @param {?string} hostClientId
    * @param {string} oauthToken
    */
   function doRegisterHost(
       hostName, privateKey, publicKey, hostClientId, oauthToken) {
     var newHostDetails = { data: {
        hostId: newHostId,
        hostName: hostName,
        publicKey: publicKey
     } };
 
-    remoting.xhr.start({
+    new remoting.Xhr({
       method: 'POST',
       url: remoting.settings.DIRECTORY_API_BASE_URL + '/@me/hosts',
       urlParams: {
         hostClientId: hostClientId
       },
-      onDone: onRegistered.bind(null, hostName, publicKey, privateKey),
       jsonContent: newHostDetails,
       oauthToken: oauthToken
-    });
+    }).then(onRegistered.bind(null, hostName, publicKey, privateKey));
   }
 
   /**
    * @param {string} hostName
    * @param {string} privateKey
    * @param {string} publicKey
    * @param {string} hostClientId
    */
   function onHostClientId(
       hostName, privateKey, publicKey, hostClientId) {
@@ skipping 264 matching lines @@
     signalStrategy.connect(
         remoting.settings.XMPP_SERVER_FOR_CLIENT, email, token);
   }
 
   remoting.identity.getToken().then(
       connectSignalingWithToken, remoting.Error.handler(onError));
 };
 
 /** @type {remoting.HostController} */
 remoting.hostController = null;