Make last message log on LogReader have channel name

Channel index is helpful, but the channel name has a lot of meaning to
folks, and includes forwarding info.  Save people a step.

Change-Id: I16aeb8dcf5aae4a21a344128ab54b3ef70b81bc9
diff --git a/aos/events/logging/log_reader.cc b/aos/events/logging/log_reader.cc
index 05555c6..e295fc1 100644
--- a/aos/events/logging/log_reader.cc
+++ b/aos/events/logging/log_reader.cc
@@ -653,7 +653,10 @@
         // data on that channel.  Not all channels will end at the same point in
         // time since they can be in different files.
         VLOG(1) << "Found the last message on channel "
-                << timestamped_message.channel_index;
+                << timestamped_message.channel_index << ", "
+                << configuration::CleanedChannelToString(
+                       logged_configuration()->channels()->Get(
+                           timestamped_message.channel_index));
 
         // The user might be working with log files from 1 node but forgot to
         // configure the infrastructure to log data for a remote channel on that