[Md Feedback] Add the rest of existing strings.

chrome/browser/resources/md_feedback/feedback_container.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.
 
 // This Polymer element is used as a container for all the feedback
 // elements. Based on a number of factors, it determines which elements
 // to show and what will be submitted to the feedback servers.
 Polymer({
   is: 'feedback-container',
+
+  /**
+   * Retrieves the feedback privacy note text, if it exists. On non-officially
+   * branded builds, the string is not defined.
+   *
+   * @return {string} Privacy note text.
+   */
+  getPrivacyNote_: function() {
+    return loadTimeData.valueExists('privacyNote') ?
+        this.i18n('privacyNote') : '';
+  },
 });