[ios Mojo] Supporting code for define WebUI function.

ios/web/webui/resources/web_ui_module_load_notifier.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.
+
+goog.provide('__crWeb.webUIModuleLoadNotifier');
+
+/**
+ * A holder class for require.js contexts whose load is pending.
+ * @constructor
+ */
+var WebUIModuleLoadNotifier = function() {
+  this.lastUsedId_ = 0;
+  this.pendingContexts_ = {};

[dpapad, 2016/05/05 17:19:59]

Does native Map
(https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Obje...)
not work well in IOS yet?

[Eugene But (OOO till 7-30), 2016/05/05 18:43:49]

It works. Thanks!

+};
+
+/**
+ * Adds the given context to the list of pending contexts.
+ * @param {string} name Name of the module that will be loaded.
+ * @param {Object} context Require.js context to hold.

[dpapad, 2016/05/05 17:19:59]

It does not seem that null/undefined values should be allowed for context. So
the annotation should be !Object (because according to Closure Compiler,
non-primitive types are nullable by default).

[Eugene But (OOO till 7-30), 2016/05/05 18:43:49]

Done.

+ * @return {string} Identifier for the added context, can be later used for
+ *     {@code moduleLoadCompleted} and {@code moduleLoadFailed} arguments.
+ */
+WebUIModuleLoadNotifier.prototype.addPendingContext = function(name, context) {
+  this.lastUsedId_++;
+  var key = name + this.lastUsedId_;
+  this.pendingContexts_[key] = context;

[dpapad, 2016/05/05 17:19:59]

Should there be a check that there is no entry for |key| already in the map?

[Eugene But (OOO till 7-30), 2016/05/05 18:43:49]

key is always a new string, because |lastUsedId_| is always incremented. So this
check will never return true.

+  return String(this.lastUsedId_);
+};
+
+/**
+ * Signals that module has successfully loaded.
+ * @param {string} name Name of the module that has been loaded.
+ * @param {String} loadId Identifier returned from {@code addPendingContext}.
+ */
+WebUIModuleLoadNotifier.prototype.moduleLoadCompleted = function(name, loadId) {
+  this.popContext_(name, loadId).completeLoad(name);
+};
+
+/**
+ * Signals that module has failed to load.
+ * @param {string} name Name of the module that has failed to load.
+ * @param {String} loadId Identifier returned from {@code addPendingContext}.
+ */
+WebUIModuleLoadNotifier.prototype.moduleLoadFailed = function(name, loadId) {
+  this.popContext_(name, loadId).onScriptFailure(name);
+};
+
+WebUIModuleLoadNotifier.prototype.popContext_ = function(name, loadId) {

[dpapad, 2016/05/05 17:19:59]

Type annotations missing.

[Eugene But (OOO till 7-30), 2016/05/05 18:43:49]

Done.

+  var key = name + loadId;
+  var context = this.pendingContexts_[key];
+  delete this.pendingContexts_[key];
+  return context;
+};