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

chrome/browser/resources/settings/about_page/detailed_build_info.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-detailed-build-info' contains detailed build
  * information for ChromeOS.
  */
 
 Polymer({
@@ skipping 37 matching lines @@
 
   /**
    * @param {string} version
    * @return {boolean}
    * @private
    */
   shouldShowVersion_: function(version) {
     return version.length > 0;
   },
 
-  /** @private */
-  onChangeChannelTap_: function() {
+  /**
+   * @param {!Event} e
+   * @private
+   */
+  onChangeChannelTap_: function(e) {
+    e.preventDefault();
     this.showChannelSwitcherDialog_ = true;
     // Async to wait for dialog to appear in the DOM.
     this.async(function() {
       var dialog = this.$$('settings-channel-switcher-dialog');
       // Register listener to detect when the dialog is closed. Flip the boolean
       // once closed to force a restamp next time it is shown such that the
       // previous dialog's contents are cleared.
       dialog.addEventListener('close', function() {
         this.showChannelSwitcherDialog_ = false;
       }.bind(this));
     }.bind(this));
   },
 });