Report download metrics for android

Report the metrics with libmetricslogger.
Tron varz added:
ota_update_engine_attempt_current_bytes_downloaded_mib
ota_update_engine_successful_update_total_bytes_downloaded_mib
ota_update_engine_successful_update_download_overhead_percentage

Test: build on sailfish
Change-Id: I4350c2030223d265a138aa07d2720413a5686d5a
diff --git a/metrics_reporter_android.h b/metrics_reporter_android.h
index 373730b..ee94e43 100644
--- a/metrics_reporter_android.h
+++ b/metrics_reporter_android.h
@@ -55,7 +55,7 @@
       int64_t payload_download_speed_bps,
       DownloadSource download_source,
       metrics::DownloadErrorCode payload_download_error_code,
-      metrics::ConnectionType connection_type) override {}
+      metrics::ConnectionType connection_type) override;
 
   void ReportAbnormallyTerminatedUpdateAttemptMetrics() override;