CRAS: audio_thread_monitor - rarefy audio thread event FRA

Audio thread event could be triggered easily and repeatedly
resulting the corresponding FRA log to cause potential syslog spam.
To mitigate this, relocate the FRA logging to occur after the
30-seconds guard period. This ensures that FRA logs coinside
with the snapshots taken in audio thread.

BUG=b:311159629
TEST=None

Change-Id: I9515a10882ce191210c790f5164ddfd4e765aa93
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/adhd/+/5036005
Tested-by: Hsinyu Chao <hychao@chromium.org>
Commit-Queue: Hsinyu Chao <hychao@chromium.org>
Tested-by: chromeos-cop-builder@chromeos-cop.iam.gserviceaccount.com <chromeos-cop-builder@chromeos-cop.iam.gserviceaccount.com>
Reviewed-by: Judy Hsiao <judyhsiao@google.com>

cras/src/server/cras_audio_thread_monitor.c

@@ -127,10 +127,6 @@ static void handle_audio_thread_event_message(struct cras_main_message* msg,
     return;
   }
 
-  FRALOG(
-      AudioThreadEvent,
-      {"type", audio_thread_event_type_to_str(audio_thread_msg->event_type)});
-
   struct timespec* last_snapshot_time =
       &last_event_snapshot_time[audio_thread_msg->event_type];
 
@@ -143,6 +139,10 @@ static void handle_audio_thread_event_message(struct cras_main_message* msg,
   subtract_timespecs(&now_time, last_snapshot_time, &diff_time);
   if (timespec_is_zero(last_snapshot_time) ||
       diff_time.tv_sec >= MIN_WAIT_SECOND) {
+    FRALOG(
+        AudioThreadEvent,
+        {"type", audio_thread_event_type_to_str(audio_thread_msg->event_type)});
+
     take_snapshot(audio_thread_msg->event_type);
     *last_snapshot_time = now_time;
   }