Add binder call tetherOffloadGetAndClearStats

Provide binder calls for getting tethering statistics and clear the
stats for the given upstream.

Bug: 150736748
Test: None
Change-Id: I7bb635ee39d658961cd9515cc37e23bc3f0cd38f
Merged-In: I7bb635ee39d658961cd9515cc37e23bc3f0cd38f
diff --git a/server/TetherController.h b/server/TetherController.h
index f8d6941..bcd2ee6 100644
--- a/server/TetherController.h
+++ b/server/TetherController.h
@@ -151,6 +151,7 @@
 
     netdutils::StatusOr<TetherStatsList> getTetherStats();
     netdutils::StatusOr<TetherOffloadStatsList> getTetherOffloadStats();
+    base::Result<TetherOffloadStats> getAndClearTetherOffloadStats(int ifIndex);
 
     /*
      * extraProcessingInfo: contains raw parsed data, and error info.