Added better error and OAuth support in xhr.js.

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 92 matching lines @@
 
   return this.signalStrategy_.getError();
 };
 
 remoting.DnsBlackholeChecker.prototype.getJid = function() {
   base.debug.assert(this.state_ == remoting.SignalStrategy.State.CONNECTED);
   return this.signalStrategy_.getJid();
 };
 
 remoting.DnsBlackholeChecker.prototype.dispose = function() {
-  if (this.xhr_) {
-    this.xhr_.abort();
-    this.xhr_ = null;
-  }
+  this.xhr_ = null;
   base.dispose(this.signalStrategy_);
   this.setState_(remoting.SignalStrategy.State.CLOSED);
 };
 
 /**
  * @param {remoting.LogToServer} logToServer The LogToServer instance for the
  *     connection.
  */
 remoting.DnsBlackholeChecker.prototype.sendConnectionSetupResults = function(
     logToServer) {
@@ skipping 23 matching lines @@
       // In case DNS blackhole is active the external state stays FAILED.
       break;
   }
 };
 
 /**
  * @param {!remoting.Xhr.Response} response
  * @private
  */
 remoting.DnsBlackholeChecker.prototype.onHttpRequestDone_ = function(response) {
+  if (this.xhr_ == null) {
+    // This happens when the dispose() method is called while a
+    // request is pending.
+    return;
+  }
+
   this.xhr_ = null;
   if (response.status >= 200 && response.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: " + response.status + " " +
@@ skipping 11 matching lines @@
  * @private
  */
 remoting.DnsBlackholeChecker.prototype.setState_ = function(newState) {
   if (this.state_ != newState) {
     this.state_ = newState;
     this.onStateChangedCallback_(this.state_);
   }
 };
 
 }());