Polymer upgraded to 1.0 in login flow.

chrome/browser/resources/chromeos/login/oobe_screen.css

 /* Copyright 2013 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 contains common styling for all the OOBE screens.
  */
 
 .step {
   box-sizing: border-box;
   position: absolute;
@@ skipping 59 matching lines @@
 }
 
 .step:not(.loading) #user-images-loading {
   visibility: hidden;
 }
 
 .step:not(.loading) #eula-busy {
   visibility: hidden;
 }
 
-/* Center spinner wrapper vertically and horizontally.
- * Vertical centering uses top: 50% and negative margin
- * instead of top: 0; bottom: 0 due to http://crbug.com/155320.
- */
 .step-loading {
-  -webkit-align-items: center;
-  -webkit-justify-content: center;
-  display: -webkit-flex;
+  align-items: center;
+  bottom: 0;
+  display: flex;
+  justify-content: center;
   left: 0;
-  margin-top: -8px;
   position: absolute;
   right: 0;
-  top: 50%;
-}
-
-.new-gaia-flow .step-loading {
-  margin-top: -42px;
+  top: 0;
 }
 
 /* Fixes perfomance problem caused by http://crbug.com/229405 . */
 .step.hidden .throbber,
 .step.hidden .spinner,
 .step.hidden .inline-spinner {
   display: none;
 }
 
 #security-info a,
@@ skipping 68 matching lines @@
 
 html[highlight=strong] #security-info a:focus,
 html[highlight=strong] #eula a:focus,
 html[highlight=strong] .step-extra-controls a:focus,
 html[highlight=strong] .menu-control:focus,
 html[highlight=strong] input[type='button']:focus,
 html[highlight=strong] button:focus {
   box-shadow: 0 0 23px rgb(77, 144, 254) !important;
 }