Don't show an error message if there isn't one.

remoting/webapp/crd/js/it2me_activity.js

Index: remoting/webapp/crd/js/it2me_activity.js
diff --git a/remoting/webapp/crd/js/it2me_activity.js b/remoting/webapp/crd/js/it2me_activity.js
index 3d4e1029f9fe9fad68e964dc4fe90bafe18c7d31..d787e11c56fd7473bec62098ae0d29843422cbdd 100644
--- a/remoting/webapp/crd/js/it2me_activity.js
+++ b/remoting/webapp/crd/js/it2me_activity.js
@@ -106,7 +106,11 @@ remoting.It2MeActivity.prototype.stop = function() {
  * @param {!remoting.Error} error
  */
 remoting.It2MeActivity.prototype.onConnectionFailed = function(error) {
-  this.showErrorMessage_(error);
+  // onConnectionFailed is also called if the connection is canceled, in which
+  // case no error message should be shown.
+  if (!error.isNone()) {
+    this.showErrorMessage_(error);
+  }
   base.dispose(this.desktopActivity_);
   this.desktopActivity_ = null;
 };