Add a test for ReplaceTrack that verifies video track content.

This verifies that replaceTrack() actually replaces the track.
Adds a new helper function to add a "signal" square into a noise track.

Bug: none
Change-Id: Ia90535c984d65adcdf2c63a5700b08d7c1e384c0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2141913
Commit-Queue: Harald Alvestrand <hta@chromium.org>
Reviewed-by: Guido Urdaneta <guidou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#758062}

third_party/blink/web_tests/external/wpt/webrtc/RTCPeerConnection-helper.js

@@ -582,7 +582,7 @@ const trackFactories = {
     return dst.stream.getAudioTracks()[0];
   },
 
-  video({width = 640, height = 480} = {}) {
+  video({width = 640, height = 480, signal = null} = {}) {
     const canvas = Object.assign(
       document.createElement("canvas"), {width, height}
     );
@@ -593,8 +593,13 @@ const trackFactories = {
     setInterval(() => {
       ctx.fillStyle = `rgb(${count%255}, ${count*count%255}, ${count%255})`;
       count += 1;
-
       ctx.fillRect(0, 0, width, height);
+      // If signal is set, add a constant-color box to the video frame.
+      if (signal !== null) {
+        ctx.fillStyle = `rgb(${signal}, ${signal}, ${signal})`;
+        ctx.fillRect(10, 10, 20, 20);
+        let pixel = ctx.getImageData(15, 15, 1, 1);
+      }
     }, 100);
 
     if (document.body) {
@@ -609,13 +614,40 @@ const trackFactories = {
   }
 };
 
+// Get the signal from a video element inserted by createNoiseStream
+function getVideoSignal(v) {
+  if (v.videoWidth < 21 || v.videoHeight < 21) {
+    return null;
+  }
+  const canvas = new OffscreenCanvas(v.videoWidth, v.videoHeight);
+  let context = canvas.getContext('2d');
+  context.drawImage(v, 0, 0, v.videoWidth, v.videoHeight);
+  // Extract pixel value at position 20, 20
+  let pixel = context.getImageData(20, 20, 1, 1);
+  return (pixel.data[0] + pixel.data[1] + pixel.data[2]) / 3;
+}
+
+function detectSignal(t, v, value) {
+  return new Promise((resolve) => {
+    let check = () => {
+      const signal = getVideoSignal(v);
+      if (signal !== null && signal < value + 1 && signal > value - 1) {
+        resolve();
+      } else {
+        t.step_timeout(check, 100);
+      }
+    }
+    check();
+  });
+}
+
 // Generate a MediaStream bearing the specified tracks.
 //
 // @param {object} [caps]
 // @param {boolean} [caps.audio] - flag indicating whether the generated stream
 //                                 should include an audio track
 // @param {boolean} [caps.video] - flag indicating whether the generated stream
-//                                 should include a video track
+//                                 should include a video track, or parameters for video
 async function getNoiseStream(caps = {}) {
   if (!trackFactories.canCreate(caps)) {
     return navigator.mediaDevices.getUserMedia(caps);
@@ -627,7 +659,7 @@ async function getNoiseStream(caps = {}) {
   }
 
   if (caps.video) {
-    tracks.push(trackFactories.video());
+    tracks.push(trackFactories.video(caps.video));
   }
 
   return new MediaStream(tracks);

third_party/blink/web_tests/external/wpt/webrtc/RTCRtpSender-replaceTrack.https-expected.txt

@@ -8,5 +8,6 @@ PASS Calling replaceTrack(null) on sender not set to session description should
 PASS Calling replaceTrack(null) on sender set to session description should resolve with sender.track set to null
 PASS Calling replaceTrack on sender with stopped track and and set to session description should resolve with sender.track set to given track
 PASS Calling replaceTrack on sender with similar track and and set to session description should resolve with sender.track set to new track
+PASS ReplaceTrack transmits the new track not the old track
 Harness: the test ran to completion.
 

third_party/blink/web_tests/external/wpt/webrtc/RTCRtpSender-replaceTrack.https.html

@@ -272,5 +272,35 @@
                 without negotiating.
             3.  Queue a task that runs the following steps:
               1.  If connection's [[isClosed]] slot is true, abort these steps.
-   */
+  */
+
+promise_test(async t => {
+  const v = document.createElement('video');
+  v.autoplay = true;
+  const pc1 = new RTCPeerConnection();
+  t.add_cleanup(() => pc1.close());
+  const pc2 = new RTCPeerConnection();
+  t.add_cleanup(() => pc2.close());
+  const stream1 = await getNoiseStream({video: {signal: 20}});
+  t.add_cleanup(() => stream1.getTracks().forEach(track => track.stop()));
+  const [track1] = stream1.getTracks();
+  const stream2 = await getNoiseStream({video: {signal: 250}});
+  t.add_cleanup(() => stream2.getTracks().forEach(track => track.stop()));
+  const [track2] = stream2.getTracks();
+  const sender = pc1.addTrack(track1);
+  pc2.ontrack = (e) => {
+    v.srcObject = new MediaStream([e.track]);
+  };
+  const metadataToBeLoaded = new Promise((resolve) => {
+    v.addEventListener('loadedmetadata', () => {
+      resolve();
+    });
+  });
+  exchangeIceCandidates(pc1, pc2);
+  doSignalingHandshake(pc1, pc2);
+  await metadataToBeLoaded;
+  await detectSignal(t, v, 20);
+  await sender.replaceTrack(track2);
+  await detectSignal(t, v, 250);
+}, 'ReplaceTrack transmits the new track not the old track');
 </script>

third_party/blink/web_tests/virtual/webrtc-wpt-plan-b/external/wpt/webrtc/RTCRtpSender-replaceTrack.https-expected.txt

@@ -8,5 +8,6 @@ FAIL Calling replaceTrack(null) on sender not set to session description should
 FAIL Calling replaceTrack(null) on sender set to session description should resolve with sender.track set to null promise_test: Unhandled rejection with value: object "InvalidStateError: Failed to execute 'addTransceiver' on 'RTCPeerConnection': This operation is only supported in 'unified-plan'."
 FAIL Calling replaceTrack on sender with stopped track and and set to session description should resolve with sender.track set to given track promise_test: Unhandled rejection with value: object "InvalidStateError: Failed to execute 'addTransceiver' on 'RTCPeerConnection': This operation is only supported in 'unified-plan'."
 FAIL Calling replaceTrack on sender with similar track and and set to session description should resolve with sender.track set to new track promise_test: Unhandled rejection with value: object "InvalidStateError: Failed to execute 'addTransceiver' on 'RTCPeerConnection': This operation is only supported in 'unified-plan'."
+PASS ReplaceTrack transmits the new track not the old track
 Harness: the test ran to completion.