Add support for inbound rtp trackIdentifier stat field

https://bugs.webkit.org/show_bug.cgi?id=250450
rdar://problem/104118773

Expose trackIdentifier and remove receiverId.
This is needed as track stats might be removed in the future.

Reviewed by Eric Carlson.

* LayoutTests/webrtc/video-stats.html:
* Source/WebCore/Modules/mediastream/RTCStatsReport.h:
* Source/WebCore/Modules/mediastream/RTCStatsReport.idl:
* Source/WebCore/Modules/mediastream/libwebrtc/LibWebRTCStatsCollector.cpp:
(WebCore::fillInboundRtpStreamStats):

Canonical link: https://commits.webkit.org/258835@main

Author: youennf

LayoutTests/webrtc/video-stats.html

@@ -122,8 +122,9 @@
 function checkInboundFramesNumberIncreased(secondConnection, statsSecondConnection, count)
 {
     return getInboundRTPStats(secondConnection).then((stats) => {
-        assert_true("framesDropped" in stats);
-        assert_true(!!stats.kind);
+        assert_true("framesDropped" in stats, "framesDropped");
+        assert_true(!!stats.trackIdentifier, "trackIdentifier");
+        assert_true(!!stats.kind, "kind");
         if (stats.framesDecoded > statsSecondConnection.framesDecoded) {
             if (testTimestampDifference(stats.timestamp - statsSecondConnection.timestamp, stats.framesDecoded - statsSecondConnection.framesDecoded))
                 return Promise.reject("timestamp and frames increment do not match");

Source/WebCore/Modules/mediastream/RTCStatsReport.h

@@ -89,7 +89,7 @@ class RTCStatsReport : public RefCounted<RTCStatsReport> {
     struct InboundRtpStreamStats : ReceivedRtpStreamStats {
         InboundRtpStreamStats() { type = RTCStatsReport::Type::InboundRtp; }
 
-        String receiverId;
+        String trackIdentifier;
         String remoteId;
         std::optional<uint32_t> framesDecoded;
         std::optional<uint32_t> keyFramesDecoded;

Source/WebCore/Modules/mediastream/RTCStatsReport.idl

@@ -88,8 +88,7 @@ dictionary RTCReceivedRtpStreamStats : RTCRtpStreamStats {
 
 [ JSGenerateToJSObject ]
 dictionary RTCInboundRtpStreamStats : RTCReceivedRtpStreamStats {
-    // required DOMString receiverId;
-    DOMString remoteId;
+    required DOMString trackIdentifier;
     unsigned long framesDecoded;
     unsigned long keyFramesDecoded;
     unsigned long frameWidth;

Source/WebCore/Modules/mediastream/libwebrtc/LibWebRTCStatsCollector.cpp

@@ -91,8 +91,11 @@ static inline void fillInboundRtpStreamStats(RTCStatsReport::InboundRtpStreamSta
 {
     fillReceivedRtpStreamStats(stats, rtcStats);
 
-    // receiverId
-    // remoteId
+    if (rtcStats.track_identifier.is_defined())
+        stats.trackIdentifier = fromStdString(*rtcStats.track_identifier);
+    if (rtcStats.remote_id.is_defined())
+        stats.remoteId = fromStdString(*rtcStats.remote_id);
+
     if (rtcStats.packets_received.is_defined())
         stats.packetsReceived = *rtcStats.packets_received;
     if (rtcStats.frames_dropped.is_defined())