Use base::Clock in AuthManager for better testing

Change-Id: Ifbb23e4da565a1c86ff728803d2e07e3f8c3b1f4
Reviewed-on: https://weave-review.googlesource.com/1873
Reviewed-by: Alex Vakulenko <avakulenko@google.com>
diff --git a/src/component_manager_impl.h b/src/component_manager_impl.h
index 426b4b0..6b8ff13 100644
--- a/src/component_manager_impl.h
+++ b/src/component_manager_impl.h
@@ -191,6 +191,7 @@
 
   base::DefaultClock default_clock_;
   base::Clock* clock_{nullptr};
+
   // An ID of last state change update. Each NotifyPropertiesUpdated()
   // invocation increments this value by 1.
   UpdateID last_state_change_id_{0};