Refactors parse_html_subset() into i18n_behavior.

ui/webui/resources/js/i18n_behavior.js

 // Copyright 2015 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
  * 'I18nBehavior' is a behavior to mix in loading of
  * internationalization strings.
  *
  * Example:
  *   behaviors: [
  *     I18nBehavior,
  *   ],
  */
 
 /** @polymerBehavior */
 var I18nBehavior = {
   /**
+   * Returns a translated string where $1 to $9 are replaced by the given
+   * values.
    * @param {string} id The ID of the string to translate.
-   * @param {...string} var_args Placeholders required by the string ($0-9).
+   * @param {...string} var_args Values to replace the placeholders $1 to $9
+   *     in the string.
    * @return {string} A translated, substituted string.
    */
-  i18n: function(id, var_args) {
+  i18nRaw: function(id, var_args) {
     return arguments.length == 1 ? loadTimeData.getString(id) :
         loadTimeData.getStringF.apply(loadTimeData, arguments);
   },
+
+  /**
+   * Returns a translated string where $1 to $9 are replaced by the given
+   * values. Also sanitizes the output to filter out dangerous HTML/JS.
+   * @param {string} id The ID of the string to translate.
+   * @param {...string} var_args Values to replace the placeholders $1 to $9
+   *     in the string.
+   * @return {string} A translated, sanitized, substituted string.
+   */
+  i18n: function(id, var_args) {
+    var rawString = this.i18nRaw.apply(this, arguments);
+    return parseHtmlSubset('<b>' + rawString + '</b>').firstChild.innerHTML;
+  },
+
+  /**
+   * Similar to 'i18n', returns a translated, sanitized, substituted string.
+   * It receives the string ID and a dictionary containing the substitutions
+   * as well as optional additional allowed tags and attributes.
+   * @param {string} id The ID of the string to translate.
+   * @param {{substitutions: (Array<string>|undefined),
+   *          attrs: (Object<function(Node, string):boolean>|undefined),
+   *          tags: (Array<string>|undefined)}} opts
+   */
+  i18nAdvanced: function(id, opts) {
+    var args = [id].concat(opts.substitutions || []);
+    var rawString = this.i18nRaw.apply(this, args);
+    return parseHtmlSubset('<b>' + rawString + '</b>', opts.tags, opts.attrs)
+        .firstChild.innerHTML;
+  }
 };