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

chrome/browser/resources/settings/site_settings/site_details.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
  * 'site-details' show the details (permissions and usage) for a given origin
  * under Site Settings.
  */
 Polymer({
@@ skipping 65 matching lines @@
       this.$.usageApi.fetchUsageTotal(this.toUrl(origin).hostname);
   },
 
   /** @private */
   onCloseDialog_: function() {
     this.$.confirmDeleteDialog.close();
   },
 
   /**
    * Confirms the deletion of storage for a site.
+   * @param {!Event} e
    * @private
    */
-  onConfirmClearStorage_: function() {
+  onConfirmClearStorage_: function(e) {
+    e.preventDefault();
     this.confirmationDeleteMsg_ = loadTimeData.getStringF(
         'siteSettingsSiteRemoveConfirmation',
         this.toUrl(this.site.origin).href);
     this.$.confirmDeleteDialog.showModal();
   },
 
   /**
    * Clears all data stored for the current origin.
    * @private
    */
@@ skipping 41 matching lines @@
   /**
    * Returns true if one or more permission is showing.
    * @private
    */
   permissionShowing_: function() {
     return Array.prototype.some.call(
         this.root.querySelectorAll('site-details-permission'),
         function(element) { return element.offsetHeight > 0; });
   },
 });