Add support for asynchronously loading modules from the background page.

extensions/renderer/resources/serial_custom_bindings.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.
 
 /**
  * Custom bindings for the Serial API.
  *
  * The bindings are implemented by asynchronously delegating to the
  * serial_service module. The functions that apply to a particular connection
  * are delegated to the appropriate method on the Connection object specified by
  * the ID parameter.
  */
 
 var binding = require('binding').Binding.create('serial');
+var utils = require('utils');
 
-function createAsyncProxy(targetPromise, functionNames) {
-  var functionProxies = {};
-  $Array.forEach(functionNames, function(name) {
-    functionProxies[name] = function() {
-      var args = arguments;
-      return targetPromise.then(function(target) {
-        return $Function.apply(target[name], target, args);
-      });
-    };
-  });
-  return functionProxies;
-}
-
-var serialService = createAsyncProxy(requireAsync('serial_service'), [
+var serialService = utils.createAsyncProxy(
+    utils.requireAsyncFromBackgroundPage('serial_service'), [
   'getDevices',
   'createConnection',
   'getConnection',
   'getConnections',
 ]);
 
 function forwardToConnection(methodName) {
   return function(connectionId) {
     var args = $Array.slice(arguments, 1);
     return serialService.getConnection(connectionId).then(function(connection) {
@@ skipping 35 matching lines @@
       var promises = [];
       for (var id in connections) {
         promises.push(connections[id].getInfo());
       }
       return Promise.all(promises);
     });
   });
 });
 
 exports.binding = binding.generate();