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

chrome/browser/resources/settings/reset_page/reset_profile_banner.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-reset-profile-banner' is the banner shown for clearing profile
  * settings.
  */
 Polymer({
   is: 'settings-reset-profile-banner',
 
   properties: {
     showResetProfileDialog_: {
       type: Boolean,
       value: false,
     },
   },
 
   /** @private */
   onCloseTap_: function() {
     settings.ResetBrowserProxyImpl.getInstance().onHideResetProfileBanner();
     this.remove();
   },
 
   /**
    * Shows a <settings-reset-profile-dialog>.
+   * @param {!Event} e
    * @private
    */
-  showDialog_: function() {
+  showDialog_: function(e) {
+    e.preventDefault();
     this.showResetProfileDialog_ = true;
   },
 
   /** @private */
   onDialogClose_: function() {
     this.showResetProfileDialog_ = false;
   },
 });