Add a function to allow statslog failure.

+ Record all types of failures which lead to log loss
+ Only record eventual failure after the retries to get a accurate log loss count.

Bug: 80538532
Test: manually tested

Change-Id: I23a55e62e140bf22ae5aa9e6c40539d51149cd66
Merged-In: I23a55e62e140bf22ae5aa9e6c40539d51149cd66
(cherry picked from commit ad3a40bf76b670878760738765154448772243fb)
diff --git a/libstats/statsd_writer.h b/libstats/statsd_writer.h
index 82e14e0..7289441 100644
--- a/libstats/statsd_writer.h
+++ b/libstats/statsd_writer.h
@@ -38,6 +38,8 @@
     void (*close)();    /* free up resources */
     /* write log to transport, returns number of bytes propagated, or -errno */
     int (*write)(struct timespec* ts, struct iovec* vec, size_t nr);
+    /* note one log drop */
+    void (*noteDrop)();
 };
 
 #endif  // ANDROID_STATS_LOG_STATS_WRITER_H