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

ui/webui/resources/js/cr.js

 // Copyright (c) 2012 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.
 
 /**
  * The global object.
  * @type {!Object}
  * @const
  */
 var global = this;
@@ skipping 300 matching lines @@
         var target = opt_target ? document.getElementById(opt_target) :
                      ctor.getInstance();
         return target[method + '_'].apply(target, arguments);
       };
     });
   }
 
   /**
    * The mapping used by the sendWithPromise mechanism to tie the Promise
    * returned to callers with the corresponding WebUI response. The mapping is
-   * from ID to the Promise resolver function; the ID is generated by
+   * from ID to the PromiseResolver helper; the ID is generated by
    * sendWithPromise and is unique across all invocations of said method.
-   * @type {!Object<!Function>}
+   * @type {!Object<!PromiseResolver>}
    */
   var chromeSendResolverMap = {};
 
   /**
    * The named method the WebUI handler calls directly in response to a
    * chrome.send call that expects a response. The handler requires no knowledge
    * of the specific name of this method, as the name is passed to the handler
    * as the first argument in the arguments list of chrome.send. The handler
    * must pass the ID, also sent via the chrome.send arguments list, as the
    * first argument of the JS invocation; additionally, the handler may
    * supply any number of other arguments that will be included in the response.
    * @param {string} id The unique ID identifying the Promise this response is
    *     tied to.
+   * @param {boolean} isSuccess Whether the request was successful.
    * @param {*} response The response as sent from C++.
    */
-  function webUIResponse(id, response) {
-    var resolverFn = chromeSendResolverMap[id];
+  function webUIResponse(id, isSuccess, response) {
+    var resolver = chromeSendResolverMap[id];
     delete chromeSendResolverMap[id];
-    resolverFn(response);
+
+    if (isSuccess)
+      resolver.resolve(response);
+    else
+      resolver.reject(response);
   }
 
   /**
    * A variation of chrome.send, suitable for messages that expect a single
    * response from C++.
    * @param {string} methodName The name of the WebUI handler API.
    * @param {...*} var_args Varibale number of arguments to be forwarded to the
    *     C++ call.
    * @return {!Promise}
    */
   function sendWithPromise(methodName, var_args) {
     var args = Array.prototype.slice.call(arguments, 1);
-    return new Promise(function(resolve, reject) {
-      var id = methodName + '_' + createUid();
-      chromeSendResolverMap[id] = resolve;
-      chrome.send(methodName, [id].concat(args));
-    });
+    var promiseResolver = new PromiseResolver();
+    var id = methodName + '_' + createUid();
+    chromeSendResolverMap[id] = promiseResolver;
+    chrome.send(methodName, [id].concat(args));
+    return promiseResolver.promise;
   }
 
   /**
    * A map of maps associating event names with listeners. The 2nd level map
    * associates a listener ID with the callback function, such that individual
    * listeners can be removed from an event without affecting other listeners of
    * the same event.
    * @type {!Object<!Object<!Function>>}
    */
   var webUIListenerMap = {};
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     get isLinux() {
       return /Linux/.test(navigator.userAgent);
     },
 
     /** Whether this is on Android. */
     get isAndroid() {
       return /Android/.test(navigator.userAgent);
     }
   };
 }();