Reland "Fix GetStats bytesSent/Received, wireup headerBytesSent/Received"

This is a reland of fbde32e596f06893d6dda13eb7d29f4c251cf08b

The chromium problem should be fixed with
https://chromium-review.googlesource.com/c/chromium/src/+/1862437

Original change's description:
> Fix GetStats bytesSent/Received, wireup headerBytesSent/Received
>
> Changes the standard GetStats, legacy GetStats unchanged.
>
> Bug: webrtc:10525
> Change-Id: Ie10fe8079f1d8b4cc6bbe513f6a2fc91477b5441
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/156084
> Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
> Reviewed-by: Henrik Boström <hbos@webrtc.org>
> Reviewed-by: Harald Alvestrand <hta@webrtc.org>
> Commit-Queue: Niels Moller <nisse@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#29462}

Tbr: kwiberg@webrtc.org
Bug: webrtc:10525
Change-Id: I3b61f9535aa3f1fca2ed84f068233803d4ec9fe2
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/157045
Reviewed-by: Niels Moller <nisse@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29485}
diff --git a/api/stats/rtcstats_objects.h b/api/stats/rtcstats_objects.h
index 5fab85e..f26c574 100644
--- a/api/stats/rtcstats_objects.h
+++ b/api/stats/rtcstats_objects.h
@@ -413,6 +413,7 @@
   RTCStatsMember<uint64_t> fec_packets_received;
   RTCStatsMember<uint64_t> fec_packets_discarded;
   RTCStatsMember<uint64_t> bytes_received;
+  RTCStatsMember<uint64_t> header_bytes_received;
   RTCStatsMember<int32_t> packets_lost;  // Signed per RFC 3550
   RTCStatsMember<double> last_packet_received_timestamp;
   // TODO(hbos): Collect and populate this value for both "audio" and "video",
@@ -466,6 +467,7 @@
   RTCStatsMember<uint32_t> packets_sent;
   RTCStatsMember<uint64_t> retransmitted_packets_sent;
   RTCStatsMember<uint64_t> bytes_sent;
+  RTCStatsMember<uint64_t> header_bytes_sent;
   RTCStatsMember<uint64_t> retransmitted_bytes_sent;
   // TODO(hbos): Collect and populate this value. https://bugs.webrtc.org/7066
   RTCStatsMember<double> target_bitrate;