Make Hands-Off Zero-Touch Enrollment compatibile with tests

chromeos/network/portal_detector/network_portal_detector.h

Index: chromeos/network/portal_detector/network_portal_detector.h
diff --git a/chromeos/network/portal_detector/network_portal_detector.h b/chromeos/network/portal_detector/network_portal_detector.h
index f5cf75646a90af632d0f72049089c77fda3bc56c..d20017b94232ff6f0f92e0249df18d03caf93d92 100644
--- a/chromeos/network/portal_detector/network_portal_detector.h
+++ b/chromeos/network/portal_detector/network_portal_detector.h
@@ -138,6 +138,8 @@ CHROMEOS_EXPORT void SetNetworkPortalDetector(
 // and deleted by Shutdown().
 CHROMEOS_EXPORT void InitializeForTesting(
     NetworkPortalDetector* network_portal_detector);
+
+// Returns true if the network portal detector has been set for testing.
 CHROMEOS_EXPORT bool SetForTesting();
 
 }  // namespace network_portal_detector