Implement host settings migration.

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) {
+    result.resolve(options);
+  })
+  return result.promise();
+};
+
+
+}());