[CrOS Tether] ProximityAuth WebUI improvement: show the local device's ID.

components/proximity_auth/webui/resources/proximity_auth.css

 /* Copyright 2017 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.
  */
 
 table {
   margin-left: 10px;
 }
 
 td {
@@ skipping 13 matching lines @@
 }
 
 tr.subrow td:first-of-type {
   text-align: right;
 }
 
 .flex {
   flex: 1;
 }
 
+#local-device-id {
+  font-family: monospace;
+}
+
 .remote-device {
   display: flex;
   flex-direction: column;
   width: 100%;
 }
 
 .remote-device:hover {
   background-color: #eee;
 }
 
@@ skipping 30 matching lines @@
 }
 
 .remote-device button {
   margin: 0px 2px;
 }
 
 #eligible-devices-list[device-count='0'],
 #ineligible-devices-list[device-count='0'] {
   display: none;
 }