signin: Abort previous 'channelConnected' handling on retry

chrome/browser/resources/gaia_auth/channel.js

 // Copyright 2013 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.
 
 /**
  * Channel to the background script.
  */
 function Channel() {
+  this.messageCallbacks_ = {};
+  this.internalRequestCallbacks_ = {};
 }
 
 /** @const */
 Channel.INTERNAL_REQUEST_MESSAGE = 'internal-request-message';
 
 /** @const */
 Channel.INTERNAL_REPLY_MESSAGE = 'internal-reply-message';
 
 Channel.prototype = {
   // Message port to use to communicate with background script.
   port_: null,
 
   // Registered message callbacks.
-  messageCallbacks_: {},
+  messageCallbacks_: null,
 
   // Internal request id to track pending requests.
   nextInternalRequestId_: 0,
 
   // Pending internal request callbacks.
-  internalRequestCallbacks_: {},
+  internalRequestCallbacks_: null,
 
   /**
    * Initialize the channel with given port for the background script.
    */
   init: function(port) {
     this.port_ = port;
     this.port_.onMessage.addListener(this.onMessage_.bind(this));
   },
 
   /**
@@ skipping 71 matching lines @@
   }
 };
 
 /**
  * Class factory.
  * @return {Channel}
  */
 Channel.create = function() {
   return new Channel();
 };