Add support for custom entries in <cr_network_select/>.

ui/webui/resources/cr_elements/network/cr_network_list_custom_item.js

Index: ui/webui/resources/cr_elements/network/cr_network_list_custom_item.js
diff --git a/ui/webui/resources/cr_elements/network/cr_network_list_custom_item.js b/ui/webui/resources/cr_elements/network/cr_network_list_custom_item.js
new file mode 100644
index 0000000000000000000000000000000000000000..13af5194eb4279bbb537f0da68656736f71eeb25
--- /dev/null
+++ b/ui/webui/resources/cr_elements/network/cr_network_list_custom_item.js
@@ -0,0 +1,69 @@
+// 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 Polymer element for displaying information about a network
+ * in a list or summary based on ONC state properties.
+ */
+(function() {
+'use strict';
+
+/**
+ * Polymer class definition for 'cr-network-list-custom-item'.
+ * Note: on-tapaction on this item fires "custom-item-selected" event
+ * with |itemState| as data.
+ */
+Polymer({
+  is: 'cr-network-list-custom-item',
+
+  properties: {
+    /**
+     * Custom entry properties.
+     * @type {?CrNetworkList.CustomItemState}
+     */
+    itemState: {
+      type: Object,
+      value: null,
+    },
+  },
+
+  listeners: {
+    'tap' : 'onTap_'
+  },
+
+  /**
+   * @param {!Event} event
+   */
+  onTap_: function(event) {
+    if (!this.itemState)
+      return;
+
+    this.fire("custom-item-selected", this.itemState);
+  },
+
+  /**
+   * TODO(stevenjb): Replace getText with a proper localization function that
+   * handles string substitution.
+   * Performs argument substitution, replacing $1, $2, etc in 'text' with
+   * corresponding entries in |args|.
+   * @param {string} text The string to perform the substitution on.
+   * @param {?Array<string>=} opt_args The arguments to replace $1, $2, etc
+   *                                   with.
+   */
+  getText_: function(text, opt_args) {
+    var res;
+    if (loadTimeData && loadTimeData.data_)
+      res = loadTimeData.getString(text) || text;
+    else
+      res = text;
+    if (!opt_args)
+      return res;
+    for (let i = 0; i < opt_args.length; ++i) {
+      let key = '$' + (i + 1);
+      res = res.replace(key, opt_args[i]);
+    }
+    return res;
+  },
+});
+})();