[MD Settings] Add title to show/hide password button.

chrome/browser/resources/settings/passwords_and_forms_page/password_edit_dialog.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.
 
 /**
  * @fileoverview 'password-edit-dialog' is the dialog that allows showing a
  *     saved password.
  */
 
 (function() {
@@ skipping 28 matching lines @@
    * Gets the password input's type. Should be 'text' when password is visible
    * and 'password' when it's not.
    * @param {string} password
    * @private
    */
   getPasswordInputType_: function(password) {
     return password ? 'text' : 'password';
   },
 
   /**
+   * Gets the title text for the show/hide icon.
+   * @param {string} password
+   * @param {string} hide The i18n text to use for 'Hide'
+   * @param {string} show The i18n text to use for 'Show'
+   * @private
+   */
+  showPasswordTitle_: function(password, hide, show) {
+    return password ? hide : show;
+  },
+
+  /**
    * Gets the text of the password. Will use the value of |password| unless it
    * cannot be shown, in which case it will be spaces.
    * @param {!chrome.passwordsPrivate.PasswordUiEntry} item
    * @param {string} password
    * @private
    */
   getPassword_: function(item, password) {
     if (password)
       return password;
     return item ? ' '.repeat(item.numCharactersInPassword) : '';
@@ skipping 22 matching lines @@
   /**
    * Handler for tapping the save button.
    * @private
    */
   onSaveButtonTap_: function() {
     // TODO(hcarmona): what to save?
     this.close();
   },
 });
 })();