[multi-profiles] Allow bringing up sign in UI even if all users are restricted per their policies

chrome/browser/resources/login/user_pod_row.css

 /* Copyright 2014 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.
  *
  * This is the stylesheet used by user pods row of account picker UI.
  */
 
 podrow {
   /* Temporarily disabled because animation interferes with updating screen's
    size. */
@@ skipping 282 matching lines @@
 }
 
 .user-type-icon-area.policy .user-type-icon-image {
   background-image: url('chrome://theme/IDR_CONTROLLED_SETTING_MANDATORY');
 }
 
 .user-type-icon-area.app .user-type-icon-image {
   background-image: url('chrome://theme/IDR_KIOSK_APP_USER_POD_ICON');
 }
 
+.bubble-shown,
 .user-type-icon-area.policy:hover ~ .user-type-bubble {
   opacity: 1;
   visibility: visible;
 }
 
 .user-type-bubble {
   -webkit-transition: all 100ms ease-in-out;
   background-color: white;
   border: 1px solid lightgray;
   border-radius: 2px;
@@ skipping 275 matching lines @@
 .pod.public-account.expanded .name,
 .pod.public-account.expanded .learn-more {
   display: none;
 }
 
 .pod.public-account.expanded .side-pane-divider,
 .pod.public-account.expanded .side-pane-container,
 .pod.public-account.animating .side-pane-container {
   visibility: inherit;
 }