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

chrome/browser/resources/settings/device_page/display.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
  * 'settings-display' is the settings subpage for display settings.
  */
 
 cr.define('settings.display', function() {
@@ skipping 352 matching lines @@
           id = display.id;
           break;
         }
       }
       properties.mirroringSourceId = this.primaryDisplayId;
     }
     settings.display.systemDisplayApi.setDisplayProperties(
         id, properties, this.setPropertiesCallback_.bind(this));
   },
 
-  /** @private */
-  onOverscanTap_: function() {
+  /**
+   * @param {!Event} e
+   * @private
+   */
+  onOverscanTap_: function(e) {
+    e.preventDefault();
     this.overscanDisplayId = this.selectedDisplay.id;
     this.showOverscanDialog_(true);
   },
 
   /** @private */
   updateDisplayInfo_() {
     var displayIds = '';
     var primaryDisplay = undefined;
     var selectedDisplay = undefined;
     for (var display of this.displays) {
@@ skipping 13 matching lines @@
   },
 
   /** @private */
   setPropertiesCallback_: function() {
     if (chrome.runtime.lastError) {
       console.error(
           'setDisplayProperties Error: ' + chrome.runtime.lastError.message);
     }
   },
 });