Add uncertainty for GPS received tow field.
b/16463499

Change-Id: Ib8ddd092f3da8295345524846e3ea0bcce59ccc2
diff --git a/include/hardware/gps.h b/include/hardware/gps.h
index 75b5682..5747faa 100644
--- a/include/hardware/gps.h
+++ b/include/hardware/gps.h
@@ -1387,6 +1387,11 @@
     int64_t received_gps_tow_ns;
 
     /**
+     * 1-Sigma uncertainty of the Received GPS Time-of-Week in nanoseconds.
+     */
+    int64_t received_gps_tow_uncertainty_ns;
+
+    /**
      * Carrier-to-noise density in dB-Hz, in the range [0, 63].
      * It contains the measured C/N0 value for the signal at the antenna input.
      *