Gentle introduction of log backend

The goal is to be able to write short logs to the pre-allocated
memory. To do that, we want to decouple file operations from logs
behind light abstraction.

There are a couple of TODO added. I hope to fix them with next iteration
where actual memory log backend will be implemented.

Change-Id: I65e80825b1e080375efc54f35b270df1ceb17a0d
Signed-off-by: Austin Schuh <austin.linux@gmail.com>
diff --git a/aos/events/logging/logger_main.cc b/aos/events/logging/logger_main.cc
index f0582dc..0dbfc8d 100644
--- a/aos/events/logging/logger_main.cc
+++ b/aos/events/logging/logger_main.cc
@@ -48,8 +48,7 @@
 
   aos::ShmEventLoop event_loop(&config.message());
 
-  std::unique_ptr<aos::logger::MultiNodeLogNamer> log_namer;
-  log_namer = std::make_unique<aos::logger::MultiNodeLogNamer>(
+  auto log_namer = std::make_unique<aos::logger::MultiNodeFilesLogNamer>(
       absl::StrCat(aos::logging::GetLogName("fbs_log"), "/"), &event_loop);
 
   if (FLAGS_snappy_compress) {