Updated XHR API so call sites are more descriptive.

remoting/webapp/crd/js/dns_blackhole_checker.js

 // Copyright 2015 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 || {};
 
 (function() {
@@ skipping 20 matching lines @@
 
   /** @private {?function(remoting.SignalStrategy.State):void} */
   this.onStateChangedCallback_ = null;
 
   /** @private */
   this.state_ = remoting.SignalStrategy.State.NOT_CONNECTED;
 
   /** @private */
   this.blackholeState_ = BlackholeState.PENDING;
 
-  /** @private {?XMLHttpRequest} */
+  /** @private {?remoting.Xhr} */
   this.xhr_ = null;
 };
 
 /**
  * @const
  * @private
  */
 remoting.DnsBlackholeChecker.URL_TO_REQUEST_ =
     "https://chromoting-client.talkgadget.google.com/talkgadget/oauth/" +
     "chrome-remote-desktop-client";
@@ skipping 26 matching lines @@
  * @param {string} username
  * @param {string} authToken
  */
 remoting.DnsBlackholeChecker.prototype.connect = function(server,
                                                           username,
                                                           authToken) {
   base.debug.assert(this.onStateChangedCallback_ != null);
 
   this.signalStrategy_.connect(server, username, authToken);
 
-  this.xhr_ = remoting.xhr.start({
+  this.xhr_ = new remoting.Xhr({
     method: 'GET',
-    url: remoting.DnsBlackholeChecker.URL_TO_REQUEST_,
-    onDone: this.onHttpRequestDone_.bind(this)
+    url: remoting.DnsBlackholeChecker.URL_TO_REQUEST_
   });
+  this.xhr_.then(this.onHttpRequestDone_.bind(this));
 };
 
 remoting.DnsBlackholeChecker.prototype.getState = function() {
   return this.state_;
 };
 
 remoting.DnsBlackholeChecker.prototype.getError = function() {
   if (this.blackholeState_ == BlackholeState.BLOCKED) {
     return remoting.Error.NOT_AUTHORIZED;
   }
@@ skipping 43 matching lines @@
     case BlackholeState.OPEN:
       this.setState_(state);
       break;
     case BlackholeState.BLOCKED:
       // In case DNS blackhole is active the external state stays FAILED.
       break;
   }
 };
 
 /**
- * @param {XMLHttpRequest} xhr
+ * @param {remoting.Xhr.Response} xhrr
  * @private
  */
-remoting.DnsBlackholeChecker.prototype.onHttpRequestDone_ = function(xhr) {
+remoting.DnsBlackholeChecker.prototype.onHttpRequestDone_ = function(xhrr) {
   this.xhr_ = null;
-  if (xhr.status >= 200 && xhr.status <= 299) {
+  if (xhrr.status >= 200 && xhrr.status <= 299) {
     console.log("DNS blackhole check succeeded.");
     this.blackholeState_ = BlackholeState.OPEN;
     if (this.signalStrategy_.getState() ==
         remoting.SignalStrategy.State.CONNECTED) {
       this.setState_(remoting.SignalStrategy.State.CONNECTED);
     }
   } else {
-    console.error("DNS blackhole check failed: " + xhr.status + " " +
-                  xhr.statusText + ". Response URL: " + xhr.responseURL +
-                  ". Response Text: " + xhr.responseText);
+    console.error("DNS blackhole check failed: " + xhrr.status + " " +
+                  xhrr.statusText + ". Response URL: " + xhrr.responseUrl +
+                  ". Response Text: " + xhrr.responseText);
     this.blackholeState_ = BlackholeState.BLOCKED;
     base.dispose(this.signalStrategy_);
     this.setState_(remoting.SignalStrategy.State.FAILED);
   }
-}
+};
 
 /**
  * @param {remoting.SignalStrategy.State} newState
  * @private
  */
 remoting.DnsBlackholeChecker.prototype.setState_ = function(newState) {
   if (this.state_ != newState) {
     this.state_ = newState;
     this.onStateChangedCallback_(this.state_);
   }
 };
 
 }());