update rtp-stats-creation.html WPT outbound-rtp timing expectations

The spec has been updated such that RtcRtpOutboundStreamStats are reported as soon as negotiation is complete. This means that packets can now be zero. We should check that the stats do not exist prior to negotiation and that they do appear after negotiation.

Differential Revision: https://phabricator.services.mozilla.com/D250591

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1967577
gecko-commit: 59e7ba1d605ad0d25a4cf70b639d77fea52b4161
gecko-reviewers: dbaker, jib

Author: na-g

webrtc-stats/rtp-stats-creation.html

@@ -38,18 +38,26 @@
   localPc.addTrack(...await createTrackAndStreamWithCleanup(test, "audio"));
   localPc.addTrack(...await createTrackAndStreamWithCleanup(test, "video"));
   exchangeIceCandidates(localPc, remotePc);
-  await Promise.all([
-    exchangeOfferAnswer(localPc, remotePc),
-    new Promise(r => remotePc.ontrack = e => e.track.onunmute = r)
-  ]);
+
+  async function countOutboundRtp() {
+    const stats = await localPc.getStats();
+    return [...stats.values()]
+        .filter(({ type }) => type == "outbound-rtp").length;
+  }
+
+  assert_equals(await countOutboundRtp(), 0,
+    "No outbound rtp stats before setLocalDescription");
+  await localPc.setLocalDescription();
+  const p = remotePc.setRemoteDescription(localPc.localDescription);
+  assert_equals(await countOutboundRtp(), 0,
+    "No outbound rtp stats after setLocalDescription but before setRemoteDescription");
+  await p;
+  await remotePc.setLocalDescription();
+  await localPc.setRemoteDescription(remotePc.localDescription);
+
   const start = performance.now();
   while (true) {
-    const report = await localPc.getStats();
-    const outbound =
-      [...report.values()].filter(({type}) => type == "outbound-rtp");
-    assert_true(outbound.every(({packetsSent}) => packetsSent > 0),
-      "no outbound rtp stats before packets sent");
-    if (outbound.length == 2) {
+    if (await countOutboundRtp() == 2) {
       // One outbound stat for each track is present. We're done.
       break;
     }
@@ -58,7 +66,7 @@
     }
     await new Promise(r => test.step_timeout(r, 100));
   }
-}, "No RTCOutboundRtpStreamStats exist until packets have been sent");
+}, "No RTCRtpOutboundStreamStats should exist before negotiation completes");
 
 promise_test(async (test) => {
   const localPc = createPeerConnectionWithCleanup(test);