Part 0: Add some test-cases for sdp without msid-semantics.

Differential Revision: https://phabricator.services.mozilla.com/D23203

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1534673
gecko-commit: 05f0176414e72fea9214d49b5ff443bba1bb0d8b
gecko-integration-branch: central
gecko-reviewers: jib

webrtc/RTCTrackEvent-fire.html

@@ -47,6 +47,12 @@
 a=ssrc:3 msid:3 2
 `;
 
+const sdp4 = sdp1.replace('msid-semantic', 'unknownattr');
+
+const sdp5 = sdpBase + `
+a=msid:-
+`;
+
 async function applyRemoteDescriptionAndReturnRemoteTrackAndStreams(pc, sdp)
 {
     const testTrackPromise = new Promise(resolve  => {
@@ -56,6 +62,14 @@
     return testTrackPromise;
 }
 
+promise_test(async test => {
+    const pc = new RTCPeerConnection();
+    test.add_cleanup(() => pc.close());
+
+    const [track, streams] = await applyRemoteDescriptionAndReturnRemoteTrackAndStreams(pc, sdp0);
+    assert_equals(streams.length, 1, "track event has a stream");
+}, "When a=msid is absent, the track should still be associated with a stream");
+
 promise_test(async test => {
     const pc = new RTCPeerConnection();
     test.add_cleanup(() => pc.close());
@@ -89,6 +103,23 @@
     assert_equals(streams[0].id, "1", "msid should match");
 }, "Source-level msid should be ignored, or an error should be thrown, if a different media-level msid is present");
 
+promise_test(async test => {
+    const pc = new RTCPeerConnection();
+    test.add_cleanup(() => pc.close());
+
+    const [track, streams] = await applyRemoteDescriptionAndReturnRemoteTrackAndStreams(pc, sdp4);
+    assert_equals(streams.length, 1, "track event has a stream");
+    assert_equals(streams[0].id, "1", "msid should match");
+}, "stream ids should be found even if msid-semantic is absent");
+
+promise_test(async test => {
+    const pc = new RTCPeerConnection();
+    test.add_cleanup(() => pc.close());
+
+    const [track, streams] = await applyRemoteDescriptionAndReturnRemoteTrackAndStreams(pc, sdp5);
+    assert_equals(streams.length, 0, "track event has no stream");
+}, "a=msid:- should result in a track event with no streams");
+
 promise_test(async test => {
     const pc = new RTCPeerConnection();
     test.add_cleanup(() => pc.close());