WebUI: Allow rejecting a promise that is returned from cr.sendWithPromise().

chrome/test/data/webui/promise_resolver.js

-// Copyright 2016 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.
-
-/**
- * @fileoverview PromiseResolver is a helper class that allows creating a
- * Promise that will be fulfilled (resolved or rejected) some time later.
- *
- * Example:
- *  var resolver = new PromiseResolver();
- *  resolver.promise.then(function(result) {
- *    console.log('resolved with', result);
- *  });
- *  ...
- *  ...
- *  resolver.resolve({hello: 'world'});
- */
-
-/**
- * @constructor
- */
-function PromiseResolver() {
-  /** @type {!Function} */
-  this.resolve;
-
-  /** @type {!Function} */
-  this.reject;
-
-  /** @type {!Promise} */
-  this.promise = new Promise(function(resolve, reject) {
-    this.resolve = resolve;
-    this.reject = reject;
-  }.bind(this));
-}