webrtc insertable streams: disable RTX in tests

in order to avoid RTX probes showing up on the receiving end

BUG=chromium:1066819

Change-Id: Icfeead1bc08557f6cb2fc3080c20b7f4bd92be29
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2144080Reviewed-by: Harald Alvestrand <hta@chromium.org>
Commit-Queue: Philipp Hancke <philipp.hancke@googlemail.com>
Cr-Commit-Position: refs/heads/master@{#760472}

third_party/blink/web_tests/fast/peerconnection/RTCPeerConnection-insertable-streams.html

@@ -29,8 +29,25 @@ function areFrameInfosEqual(frame1, frame2) {
          areArrayBuffersEqual(frame1.data, frame2.data);
 }
 
+async function doSignalingHandshake(pc1, pc2) {
+  const offer = await pc2.createOffer({offerToReceiveAudio: true, offerToReceiveVideo: true});
+  // TODO(crbug.com/1066819): remove this hack when we do not receive duplicates from RTX
+  //   anymore.
+  // Munge the SDP to disable bandwidth probing via RTX.
+  const sdp = offer.sdp.replace(new RegExp('rtx', 'g'), 'invalid');
+  await pc1.setRemoteDescription({type: 'offer', sdp});
+  await pc2.setLocalDescription(offer);
+
+  const answer = await pc1.createAnswer();
+  await pc2.setRemoteDescription(answer);
+  await pc1.setLocalDescription(answer);
+}
+
 async function doInverseSignalingHandshake(pc1, pc2) {
   const offer = await pc2.createOffer({offerToReceiveAudio: true, offerToReceiveVideo: true});
+  // Munge the SDP to disable bandwidth probing via RTX.
+  const sdp = offer.sdp.replace(new RegExp('rtx', 'g'), 'invalid');
+  await pc1.setRemoteDescription({type: 'offer', sdp});
   await pc1.setRemoteDescription(offer);
   await pc2.setLocalDescription(offer);