Introduce a new wrapper for log_msg -- LogEvent

It stores all of the parsed fields in a single vector, and
provides accessor methods to get at fields by index with
their correct type.

Test: statsd_test
Change-Id: I4fa94e4ce52db3ac87f19b62f9c85398de6e8145
diff --git a/cmds/statsd/src/StatsService.h b/cmds/statsd/src/StatsService.h
index dcc73a1..7d305e9 100644
--- a/cmds/statsd/src/StatsService.h
+++ b/cmds/statsd/src/StatsService.h
@@ -68,7 +68,7 @@
     /**
      * Called by LogReader when there's a log event to process.
      */
-    virtual void OnLogEvent(const log_msg& msg);
+    virtual void OnLogEvent(const LogEvent& event);
 
     // TODO: public for testing since statsd doesn't run when system starts. Change to private
     // later.