[Stats] Include fecPackets[Reeceived/Discarded] in Members()

This refers to modern getStats() only. The metrics has been implemented
for a while in C++ but was accidentally not included in the Members()
list, meaning they were not exposed in lists (including exposure in
Chrome/JavaScript).

The Chromium whitelist already include them.

TBR=hta@webrtc.org

Bug: webrtc:11317
Change-Id: I0c3ee9c552975fc37db2d87196c66e662c994aed
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/167530
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Commit-Queue: Henrik Boström <hbos@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#30391}
diff --git a/pc/rtc_stats_integrationtest.cc b/pc/rtc_stats_integrationtest.cc
index 381d5bd..e3f522b 100644
--- a/pc/rtc_stats_integrationtest.cc
+++ b/pc/rtc_stats_integrationtest.cc
@@ -795,6 +795,9 @@
           inbound_stream.fec_packets_received);
       verifier.TestMemberIsNonNegative<uint64_t>(
           inbound_stream.fec_packets_discarded);
+    } else {
+      verifier.TestMemberIsUndefined(inbound_stream.fec_packets_received);
+      verifier.TestMemberIsUndefined(inbound_stream.fec_packets_discarded);
     }
     verifier.TestMemberIsNonNegative<uint64_t>(inbound_stream.bytes_received);
     verifier.TestMemberIsNonNegative<uint64_t>(
diff --git a/stats/rtcstats_objects.cc b/stats/rtcstats_objects.cc
index f8122f4..77cbc09 100644
--- a/stats/rtcstats_objects.cc
+++ b/stats/rtcstats_objects.cc
@@ -594,6 +594,8 @@
 WEBRTC_RTCSTATS_IMPL(
     RTCInboundRTPStreamStats, RTCRTPStreamStats, "inbound-rtp",
     &packets_received,
+    &fec_packets_received,
+    &fec_packets_discarded,
     &bytes_received,
     &header_bytes_received,
     &packets_lost,