Reenable test RTCPeerConnection-addMultipleTracks

Performance improvements have been landed, and limits reduced
after testing on a weak cloudtop system in debug mode.
This may be enough.

Bug: chromium:1160616
Change-Id: I5ca85af0dd8bbd99f094025d979dbb7b1617d698
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2611714Reviewed-by: Tal Pressman <talp@google.com>
Commit-Queue: Harald Alvestrand <hta@chromium.org>
Cr-Commit-Position: refs/heads/master@{#840962}

third_party/blink/web_tests/TestExpectations

@@ -1569,9 +1569,6 @@ crbug.com/829740 fast/history/history-back-twice-with-subframes-assert.html [ Pa
 crbug.com/836783 fast/peerconnection/RTCRtpSender-setParameters.html [ Pass Timeout ]
 crbug.com/846981 fast/webgl/texImage-imageBitmap-from-imageData-resize.html [ Pass Timeout ]
 
-# Test failing on "Linux Tests (dbg)(1)" since it was introduced.
-crbug.com/1160616 [ Linux ] fast/peerconnection/RTCPeerConnection-addMultipleTracks.html [ Failure ]
-
 # crbug.com/1095379: These fail with a timeout, even when they're given extra time (via SlowTests)
 crbug.com/846656 external/wpt/css/selectors/focus-visible-002.html [ Pass Timeout ]
 crbug.com/1135405 http/tests/devtools/sources/debugger-pause/debugger-pause-infinite-loop.js [ Pass Timeout ]

third_party/blink/web_tests/fast/peerconnection/RTCPeerConnection-addMultipleTracks.html

@@ -48,7 +48,8 @@ async function doNegotiation(caller, callee) {
       maybeLog('Audio: Count ' + count +  ', timeTakenMs is ' + timeTakenMs);
       assert_equals(callee.getReceivers().length, count);
     }
-    assert_greater_than_equal(count, 9);
+    // 6 has been observed on a weak Linux cloudtop in debug mode.
+    assert_greater_than_equal(count, 5);
   }, 'Adding multiple audio tracks with addTrack(), one at a time');
 
   promise_test(async t => {
@@ -90,7 +91,8 @@ async function doNegotiation(caller, callee) {
       maybeLog('Video: Count ' + count +  ', timeTakenMs is ' + timeTakenMs);
       assert_equals(callee.getReceivers().length, count);
     }
-    assert_greater_than_equal(count, 4);
+    // 2 has been observed on a weak Linux cloudtop instance in debug mode.
+    assert_greater_than_equal(count, 2);
   }, 'Adding multiple video tracks with addTrack(), one at a time');
 
   promise_test(async t => {
@@ -102,7 +104,9 @@ async function doNegotiation(caller, callee) {
     const stream = await getNoiseStream({video: true});
     t.add_cleanup(() => stream.getTracks().forEach(track => track.stop()));
     const [track] = stream.getTracks();
-    const kTrackCount = 3;
+    // More than 1 second on 3 tracks has been observed
+    // on a weak Linux cloudtop in debug mode.
+    const kTrackCount = 2;
     for (let count = 1; count <= kTrackCount; count++) {
       const transceiver = caller.addTrack(track.clone());
     }