Fixed Bluetooth keyboard pairing pincode visibility issue.

chrome/browser/resources/chromeos/login/oobe_screen_hid_detection.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.
  */
 
 #hid-detection {
   min-height: 395px;
   padding: 70px 17px 21px;
   width: 622px;
 }
@@ skipping 32 matching lines @@
 #hid-keyboard-icon-block {
   display: inline;
 }
 
 #hid-mouse-label,
 #hid-keyboard-label {
   -webkit-padding-start: 10px;
   display: inline;
 }
 
-#hid-detection .label,
-#hid-keyboard-pincode {
+#hid-detection .label {
   display: none;
 }
 
 #hid-keyboard-tick,
 #hid-mouse-tick {
   -webkit-margin-start: -28px;
   bottom: -20px;
   position: relative;
   visibility: hidden;
 }
@@ skipping 22 matching lines @@
   display: inline;
 }
 
 .connected #hid-keyboard-tick,
 .connected #hid-mouse-tick,
 .paired #hid-keyboard-tick,
 .paired #hid-mouse-tick {
   visibility: visible;
 }
 
-.pairing .show-pincode #hid-keyboard-pincode {
-  display: block;
-}