Implement RTCOutboundRtpStreamStats.targetBitrate for video

Spec: https://w3c.github.io/webrtc-stats/#dom-rtcoutboundrtpstreamstats-targetbitrate

Bug: webrtc:13394
Change-Id: I4749b38088a24d1a775137d5fe2c65f96effd185
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/276380
Auto-Submit: Daniel.L (Byoungchan) Lee <daniel.l@hpcnt.com>
Commit-Queue: Henrik Boström <hbos@webrtc.org>
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#38170}

api/stats/rtcstats_objects.h

diff --git a/api/stats/rtcstats_objects.h b/api/stats/rtcstats_objects.h
index 2554ea0..b73648a 100644
--- a/api/stats/rtcstats_objects.h
+++ b/api/stats/rtcstats_objects.h
@@ -516,7 +516,6 @@
   RTCStatsMember<uint64_t> bytes_sent;
   RTCStatsMember<uint64_t> header_bytes_sent;
   RTCStatsMember<uint64_t> retransmitted_bytes_sent;
-  // TODO(https://crbug.com/webrtc/13394): Also collect this metric for video.
   RTCStatsMember<double> target_bitrate;
   RTCStatsMember<uint32_t> frames_encoded;
   RTCStatsMember<uint32_t> key_frames_encoded;

media/base/media_channel.h

diff --git a/media/base/media_channel.h b/media/base/media_channel.h
index 57b4884..986cb26 100644
--- a/media/base/media_channel.h
+++ b/media/base/media_channel.h
@@ -391,7 +391,7 @@
   // https://w3c.github.io/webrtc-stats/#dom-rtcoutboundrtpstreamstats-nackcount
   uint32_t nacks_rcvd = 0;
   // https://w3c.github.io/webrtc-stats/#dom-rtcoutboundrtpstreamstats-targetbitrate
-  double target_bitrate = 0.0;
+  absl::optional<double> target_bitrate;
   int packets_lost = 0;
   float fraction_lost = 0.0f;
   int64_t rtt_ms = 0;

media/engine/webrtc_video_engine.cc

diff --git a/media/engine/webrtc_video_engine.cc b/media/engine/webrtc_video_engine.cc
index dc404dc..5651f59 100644
--- a/media/engine/webrtc_video_engine.cc
+++ b/media/engine/webrtc_video_engine.cc
@@ -2656,6 +2656,7 @@
     common_info.quality_limitation_resolution_changes =
         stats.quality_limitation_resolution_changes;
     common_info.encoder_implementation_name = stats.encoder_implementation_name;
+    common_info.target_bitrate = stats.target_media_bitrate_bps;
     common_info.ssrc_groups = ssrc_groups_;
     common_info.frames = stats.frames;
     common_info.framerate_input = stats.input_frame_rate;

pc/rtc_stats_collector.cc

diff --git a/pc/rtc_stats_collector.cc b/pc/rtc_stats_collector.cc
index c27533a..8bcc72d 100644
--- a/pc/rtc_stats_collector.cc
+++ b/pc/rtc_stats_collector.cc
@@ -646,8 +646,9 @@
   outbound_audio->mid = mid;
   outbound_audio->media_type = "audio";
   outbound_audio->kind = "audio";
-  if (voice_sender_info.target_bitrate > 0) {
-    outbound_audio->target_bitrate = voice_sender_info.target_bitrate;
+  if (voice_sender_info.target_bitrate &&
+      *voice_sender_info.target_bitrate > 0) {
+    outbound_audio->target_bitrate = *voice_sender_info.target_bitrate;
   }
   if (voice_sender_info.codec_payload_type.has_value()) {
     auto codec_param_it = voice_media_info.send_codecs.find(
@@ -689,6 +690,10 @@
       static_cast<uint32_t>(video_sender_info.plis_rcvd);
   if (video_sender_info.qp_sum)
     outbound_video->qp_sum = *video_sender_info.qp_sum;
+  if (video_sender_info.target_bitrate &&
+      video_sender_info.target_bitrate > 0) {
+    outbound_video->target_bitrate = *video_sender_info.target_bitrate;
+  }
   outbound_video->frames_encoded = video_sender_info.frames_encoded;
   outbound_video->key_frames_encoded = video_sender_info.key_frames_encoded;
   outbound_video->total_encode_time =

pc/rtc_stats_integrationtest.cc

diff --git a/pc/rtc_stats_integrationtest.cc b/pc/rtc_stats_integrationtest.cc
index 057bf0f..e49f173 100644
--- a/pc/rtc_stats_integrationtest.cc
+++ b/pc/rtc_stats_integrationtest.cc
@@ -956,6 +956,7 @@
         outbound_stream.header_bytes_sent);
     verifier.TestMemberIsNonNegative<uint64_t>(
         outbound_stream.retransmitted_bytes_sent);
+    verifier.TestMemberIsNonNegative<double>(outbound_stream.target_bitrate);
     if (outbound_stream.kind.is_defined() && *outbound_stream.kind == "video") {
       verifier.TestMemberIsDefined(outbound_stream.frames_encoded);
       verifier.TestMemberIsDefined(outbound_stream.key_frames_encoded);
@@ -990,7 +991,6 @@
       verifier.TestMemberIsNonNegative<uint32_t>(outbound_stream.frames_sent);
       verifier.TestMemberIsNonNegative<uint32_t>(
           outbound_stream.huge_frames_sent);
-      verifier.TestMemberIsUndefined(outbound_stream.target_bitrate);
       verifier.MarkMemberTested(outbound_stream.rid, true);
     } else {
       verifier.TestMemberIsUndefined(outbound_stream.frames_encoded);
@@ -1014,7 +1014,6 @@
       verifier.TestMemberIsUndefined(outbound_stream.frame_width);
       verifier.TestMemberIsUndefined(outbound_stream.frames_sent);
       verifier.TestMemberIsUndefined(outbound_stream.huge_frames_sent);
-      verifier.TestMemberIsNonNegative<double>(outbound_stream.target_bitrate);
     }
     return verifier.ExpectAllMembersSuccessfullyTested();
   }