Support stopping and starting logging at runtime

Change-Id: If1e1b7119808d1f56e96efb71ea7000e0fa13fe8
diff --git a/y2020/control_loops/drivetrain/drivetrain_replay.cc b/y2020/control_loops/drivetrain/drivetrain_replay.cc
index 0dd5a1a..0ed57c5 100644
--- a/y2020/control_loops/drivetrain/drivetrain_replay.cc
+++ b/y2020/control_loops/drivetrain/drivetrain_replay.cc
@@ -49,7 +49,8 @@
   std::unique_ptr<aos::EventLoop> log_writer_event_loop =
       reader.event_loop_factory()->MakeEventLoop("log_writer", node);
   log_writer_event_loop->SkipTimingReport();
-  aos::logger::Logger writer(FLAGS_output_file, log_writer_event_loop.get());
+  aos::logger::Logger writer(log_writer_event_loop.get());
+  writer.StartLoggingLocalNamerOnRun(FLAGS_output_file);
 
   std::unique_ptr<aos::EventLoop> drivetrain_event_loop =
       reader.event_loop_factory()->MakeEventLoop("drivetrain", node);