Call preventDefault in all on-tap events that show a dialog.

chrome/browser/resources/settings/people_page/users_page.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
  * 'settings-users-page' is the settings page for managing user accounts on
  * the device.
  *
  * Example:
@@ skipping 37 matching lines @@
   created: function() {
     chrome.usersPrivate.isCurrentUserOwner(function(isOwner) {
       this.isOwner_ = isOwner;
     }.bind(this));
 
     chrome.usersPrivate.isWhitelistManaged(function(isWhitelistManaged) {
       this.isWhitelistManaged_ = isWhitelistManaged;
     }.bind(this));
   },
 
-  /** @private */
-  openAddUserDialog_: function() {
+  /**
+   * @param {!Event} e
+   * @private
+   */
+  openAddUserDialog_: function(e) {
+    e.preventDefault();
     this.$.addUserDialog.open();
   },
 
   /**
    * @param {boolean} isOwner
    * @param {boolean} isWhitelistManaged
    * @private
    * @return {boolean}
    */
   isEditingDisabled_: function(isOwner, isWhitelistManaged) {
     return !isOwner || isWhitelistManaged;
   },
 
   /**
    * @param {boolean} isOwner
    * @param {boolean} isWhitelistManaged
    * @param {boolean} allowGuest
    * @private
    * @return {boolean}
    */
   isEditingUsersDisabled_: function(isOwner, isWhitelistManaged, allowGuest) {
     return !isOwner || isWhitelistManaged || allowGuest;
   }
 });