Send a correctly-formatted response if there are no host options saved.

remoting/webapp/crd/js/options_export.js

 // Copyright 2017 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.
 
 /** @suppress {duplicate} */
 var remoting = remoting || {};
 
 (function(){
 
 'use strict';
 
 /**
  * @constructor
  */
 remoting.OptionsExporter = function() {
   base.Ipc.getInstance().register('getSettings',
                                   remoting.OptionsExporter.migrateSettings_,
                                   true);
 };
 
 remoting.OptionsExporter.migrateSettings_ = function() {
   var result = new base.Deferred();
-  chrome.storage.local.get('remoting-host-options', function(options) {
+  chrome.storage.local.get(KEY_NAME, function(options) {
+    // If there are no host options stored, reformat the message response so
+    // that the sender doesn't interpret it as an error.
+    if (Object.keys(options).length == 0) {
+      options[KEY_NAME] = '{}';
+    }
     result.resolve(options);
   })
   return result.promise();
 };
 
+var KEY_NAME = 'remoting-host-options';
 
 }());