Fixed callWithToken error handling.

remoting/webapp/host_controller.js

Index: remoting/webapp/host_controller.js
diff --git a/remoting/webapp/host_controller.js b/remoting/webapp/host_controller.js
index b5850dbd049958928564a45d45b53ab5a3134d85..a29779e84fd6dcae7af430cc6e51ec060e78659c 100644
--- a/remoting/webapp/host_controller.js
+++ b/remoting/webapp/host_controller.js
@@ -203,9 +203,14 @@ remoting.HostController.prototype.start = function(hostPin, callback) {
    *  @param {string} publicKey */
   function onKeyGenerated(privateKey, publicKey) {
     remoting.oauth2.callWithToken(
-        /** @param {string} oauthToken */
+        /** @param {string?} oauthToken */
         function(oauthToken) {
-          doRegisterHost(privateKey, publicKey, oauthToken);
+          if (oauthToken) {
+            doRegisterHost(privateKey, publicKey, oauthToken);
+          } else {
+            // TODO(jamiewalch): Have a more specific error code here?
+            callback(remoting.HostController.AsyncResult.FAILED);
+          }
         });
   };