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/audio/channel_send.cc b/audio/channel_send.cc
index 2a969ab..f803bf9 100644
--- a/audio/channel_send.cc
+++ b/audio/channel_send.cc
@@ -52,11 +52,6 @@
 constexpr int64_t kMaxRetransmissionWindowMs = 1000;
 constexpr int64_t kMinRetransmissionWindowMs = 30;
 
-// Field trial which controls whether to report standard-compliant bytes
-// sent/received per stream.  If enabled, padding and headers are not included
-// in bytes sent or received.
-constexpr char kUseStandardBytesStats[] = "WebRTC-UseStandardBytesStats";
-
 MediaTransportEncodedAudioFrame::FrameType
 MediaTransportFrameTypeForWebrtcFrameType(webrtc::AudioFrameType frame_type) {
   switch (frame_type) {
@@ -263,7 +258,6 @@
   rtc::ThreadChecker construction_thread_;
 
   const bool use_twcc_plr_for_ana_;
-  const bool use_standard_bytes_stats_;
 
   bool encoder_queue_is_active_ RTC_GUARDED_BY(encoder_queue_) = false;
 
@@ -609,8 +603,6 @@
           new RateLimiter(clock, kMaxRetransmissionWindowMs)),
       use_twcc_plr_for_ana_(
           webrtc::field_trial::FindFullName("UseTwccPlrForAna") == "Enabled"),
-      use_standard_bytes_stats_(
-          webrtc::field_trial::IsEnabled(kUseStandardBytesStats)),
       media_transport_config_(media_transport_config),
       frame_encryptor_(frame_encryptor),
       crypto_options_(crypto_options),
@@ -1019,17 +1011,12 @@
   StreamDataCounters rtp_stats;
   StreamDataCounters rtx_stats;
   _rtpRtcpModule->GetSendStreamDataCounters(&rtp_stats, &rtx_stats);
-  if (use_standard_bytes_stats_) {
-    stats.bytesSent = rtp_stats.transmitted.payload_bytes +
-                      rtx_stats.transmitted.payload_bytes;
-  } else {
-    stats.bytesSent = rtp_stats.transmitted.payload_bytes +
-                      rtp_stats.transmitted.padding_bytes +
-                      rtp_stats.transmitted.header_bytes +
-                      rtx_stats.transmitted.payload_bytes +
-                      rtx_stats.transmitted.padding_bytes +
-                      rtx_stats.transmitted.header_bytes;
-  }
+  stats.payload_bytes_sent =
+      rtp_stats.transmitted.payload_bytes + rtx_stats.transmitted.payload_bytes;
+  stats.header_and_padding_bytes_sent =
+      rtp_stats.transmitted.padding_bytes + rtp_stats.transmitted.header_bytes +
+      rtx_stats.transmitted.padding_bytes + rtx_stats.transmitted.header_bytes;
+
   // TODO(https://crbug.com/webrtc/10555): RTX retransmissions should show up in
   // separate outbound-rtp stream objects.
   stats.retransmitted_bytes_sent = rtp_stats.retransmitted.payload_bytes;