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/pc/rtc_stats_integrationtest.cc b/pc/rtc_stats_integrationtest.cc
index 7cb3028..0d51af0 100644
--- a/pc/rtc_stats_integrationtest.cc
+++ b/pc/rtc_stats_integrationtest.cc
@@ -797,6 +797,8 @@
           inbound_stream.fec_packets_discarded);
     }
     verifier.TestMemberIsNonNegative<uint64_t>(inbound_stream.bytes_received);
+    verifier.TestMemberIsNonNegative<uint64_t>(
+        inbound_stream.header_bytes_received);
     // packets_lost is defined as signed, but this should never happen in
     // this test. See RFC 3550.
     verifier.TestMemberIsNonNegative<int32_t>(inbound_stream.packets_lost);
@@ -856,6 +858,8 @@
         outbound_stream.retransmitted_packets_sent);
     verifier.TestMemberIsNonNegative<uint64_t>(outbound_stream.bytes_sent);
     verifier.TestMemberIsNonNegative<uint64_t>(
+        outbound_stream.header_bytes_sent);
+    verifier.TestMemberIsNonNegative<uint64_t>(
         outbound_stream.retransmitted_bytes_sent);
     verifier.TestMemberIsUndefined(outbound_stream.target_bitrate);
     if (outbound_stream.media_type.is_defined() &&