md settings: Give focus to password prompt on tap.

chrome/browser/resources/settings/people_page/people_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-people-page' is the settings page containing sign-in settings.
  */
 Polymer({
   is: 'settings-people-page',
@@ skipping 308 matching lines @@
         settings.navigateTo(settings.Route.ABOUT);
         break;
       case settings.StatusAction.ENTER_PASSPHRASE:
       case settings.StatusAction.NO_ACTION:
       default:
         settings.navigateTo(settings.Route.SYNC);
     }
   },
 
 // <if expr="chromeos">
-  /** @private */
-  onConfigureLockTap_: function() {
+  /**
+   * @param {!Event} e
+   * @private
+   */
+  onConfigureLockTap_: function(e) {
+    // Navigating to the lock screen will always open the password prompt
+    // dialog, so prevent the end of the tap event to focus what is underneath
+    // it, which takes focus from the dialog.
+    e.preventDefault();
     settings.navigateTo(settings.Route.LOCK_SCREEN);
   },
 // </if>
 
   /** @private */
   onManageOtherPeople_: function() {
 // <if expr="not chromeos">
     this.syncBrowserProxy_.manageOtherPeople();
 // </if>
 // <if expr="chromeos">
@@ skipping 104 matching lines @@
 
   /**
    * @param {!settings.SyncStatus} syncStatus
    * @return {boolean} Whether to show the "Sign in to Chrome" button.
    * @private
    */
   showSignin_: function(syncStatus) {
     return !!syncStatus.signinAllowed && !syncStatus.signedIn;
   },
 });