[Webapp Refactor] Reliably cancels a connection.

remoting/webapp/crd/js/client_session.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.
 
 /**
  * @fileoverview
  * Class handling creation and teardown of a remoting client session.
  *
  * The ClientSession class controls lifetime of the client plugin
  * object and provides the plugin with the functionality it needs to
@@ skipping 267 matching lines @@
 /**
  * Disconnect the current session with a particular |error|.  The session will
  * raise a |stateChanged| event in response to it.  The caller should then call
  * dispose() to remove and destroy the <embed> element.
  *
  * @param {!remoting.Error} error The reason for the disconnection.  Use
  *    remoting.Error.none() if there is no error.
  * @return {void} Nothing.
  */
 remoting.ClientSession.prototype.disconnect = function(error) {
+  if (this.isFinished()) {
+    return;
+  }
+
   this.sendIq_(
       '<cli:iq ' +
           'to="' + this.host_.jabberId + '" ' +
           'type="set" ' +
           'id="session-terminate" ' +
           'xmlns:cli="jabber:client">' +
         '<jingle ' +
             'xmlns="urn:xmpp:jingle:1" ' +
             'action="session-terminate" ' +
             'sid="' + this.sessionId_ + '">' +
@@ skipping 319 matching lines @@
  * For example, if attempting a connection using a cached JID, host-offline
  * errors should not be logged because the JID will be refreshed and the
  * connection retried.
  *
  * @param {boolean} enable True to log host-offline errors; false to suppress.
  */
 remoting.ClientSession.prototype.logHostOfflineErrors = function(enable) {
   this.logHostOfflineErrors_ = enable;
 };