Use a separate window to notify the user that permissions are required.

remoting/webapp/base/js/auth_dialog.js

-// Copyright 2014 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';
-
-var instance_ = null;
-
-/**
- * @constructor
- * @implements {remoting.WindowShape.ClientUI}
- * @implements {remoting.Identity.ConsentDialog}
- * @param {HTMLElement} rootElement The dialog DOM element.
- * @private
- */
-remoting.AuthDialog = function(rootElement) {
-  /** @private {HTMLElement} */
-  this.rootElement_ = rootElement;
-
-  /** @private {HTMLElement} */
-  this.borderElement_ = rootElement.querySelector('#auth-dialog-border');
-
-  /** @private {HTMLElement} */
-  this.authButton_ = rootElement.querySelector('#auth-button');
-
-  /** @private {base.Deferred} */
-  this.onAuthButtonDeferred_ = null;
-
-  this.authButton_.addEventListener('click', this.onClick_.bind(this), false);
-  remoting.windowShape.addCallback(this);
-};
-
-/**
- * @param {Array<{left: number, top: number, width: number, height: number}>}
- *     rects List of rectangles.
- */
-remoting.AuthDialog.prototype.addToRegion = function(rects) {
-  var rect =
-      /** @type {ClientRect} */(this.borderElement_.getBoundingClientRect());
-  rects.push({left: rect.left,
-              top: rect.top,
-              width: rect.width,
-              height: rect.height});
-};
-
-/** @private */
-remoting.AuthDialog.prototype.onClick_ = function() {
-  this.rootElement_.hidden = true;
-  this.onAuthButtonDeferred_.resolve(null);
-  this.onAuthButtonDeferred_ = null;
-  remoting.windowShape.updateClientWindowShape();
-};
-
-/**
- * @return {Promise} A Promise object that resolves when the user clicks on the
- *   auth button.
- */
-remoting.AuthDialog.prototype.show = function() {
-  if (this.isVisible()) {
-    return Promise.reject('Auth dialog is already showing.');
-  }
-  this.rootElement_.hidden = false;
-  base.debug.assert(this.onAuthButtonDeferred_ === null);
-  remoting.windowShape.updateClientWindowShape();
-  this.onAuthButtonDeferred_ = new base.Deferred();
-  return this.onAuthButtonDeferred_.promise();
-};
-
-/**
- * @return {boolean} whether the auth dialog is visible or not.
- */
-remoting.AuthDialog.prototype.isVisible = function() {
-  return !this.rootElement_.hidden;
-};
-
-/**
- * @return {remoting.AuthDialog}
- */
-remoting.AuthDialog.getInstance = function() {
-  if (!instance_) {
-    var rootElement = document.getElementById('auth-dialog');
-    instance_ = new remoting.AuthDialog(rootElement);
-  }
-  return instance_;
-};
-
-})();