Make Hands-Off Zero-Touch Enrollment compatibile with tests

chromeos/network/portal_detector/network_portal_detector.cc

 // 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.
 
 #include "chromeos/network/portal_detector/network_portal_detector.h"
 
 #include "base/logging.h"
 #include "components/device_event_log/device_event_log.h"
 
 namespace chromeos {
@@ skipping 66 matching lines @@
   return network_portal_detector_;
 }
 
 void SetNetworkPortalDetector(NetworkPortalDetector* network_portal_detector) {
   CHECK(!network_portal_detector_)
       << "NetworkPortalDetector was initialized twice.";
   NET_LOG(EVENT) << "SetNetworkPortalDetector";
   network_portal_detector_ = network_portal_detector;
 }
 
+void EndTest() {
+  set_for_testing_ = false;
+}
+
 }  // namespace network_portal_detector
 
 }  // namespace chromeos