webrtc wpt: trust getUserMedia to be compliant

removes assertions that (unneccesarily) assume getUserMedia returns something else than what was requested

BUG=836871

Change-Id: If8f52f259ea924bdc9ac68a854c34188f3f56cda
Reviewed-on: https://chromium-review.googlesource.com/1105528Reviewed-by: Henrik Boström <hbos@chromium.org>
Commit-Queue: Henrik Boström <hbos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568407}

third_party/WebKit/LayoutTests/external/wpt/webrtc/RTCPeerConnection-getStats.https.html

@@ -244,26 +244,12 @@
     })
     .then(t.step_func(mediaStream => {
       const tracks = mediaStream.getTracks();
-      assert_equals(tracks.length, 2,
-        'Expect media stream to have one audio and one video track');
+      const [audioTrack] = mediaStream.getAudioTracks();
+      const [videoTrack] = mediaStream.getVideoTracks();
 
-      let audioTrack;
-      let videoTrack;
-
-      for (const track of tracks) {
+      for (const track of mediaStream.getTracks()) {
         t.add_cleanup(() => track.stop());
-
         pc1.addTrack(track, mediaStream);
-
-        if (track.kind === 'audio') {
-          audioTrack = track;
-        } else if (track.kind === 'video') {
-          videoTrack = track;
-        }
-      }
-
-      if (!audioTrack || ! videoTrack) {
-        assert_unreached('Expect mediaStream to have both audio and video streams');
       }
 
       const testStatsReport = (pc, statsReport) => {

third_party/WebKit/LayoutTests/external/wpt/webrtc/RTCPeerConnection-helper.js

@@ -357,10 +357,7 @@ function generateMediaStreamTrack(kind) {
 function getTrackFromUserMedia(kind) {
   return navigator.mediaDevices.getUserMedia({ [kind]: true })
   .then(mediaStream => {
-    const tracks = mediaStream.getTracks();
-    assert_greater_than(tracks.length, 0,
-      `Expect getUserMedia to return at least one track of kind ${kind}`);
-    const [ track ] = tracks;
+    const [track] = mediaStream.getTracks();
     return [track, mediaStream];
   });
 }

third_party/WebKit/LayoutTests/external/wpt/webrtc/RTCPeerConnection-removeTrack.https.html

@@ -53,11 +53,7 @@
 
     return navigator.mediaDevices.getUserMedia({ audio: true })
     .then(mediaStream => {
-      const tracks = mediaStream.getTracks();
-      assert_greater_than(tracks.length, 0,
-        'Expect getUserMedia to return at least one audio track');
-
-      const track = tracks[0];
+      const [track] = mediaStream.getTracks();
       const sender = pc.addTrack(track, mediaStream);
 
       pc.close();
@@ -84,11 +80,7 @@
 
     return navigator.mediaDevices.getUserMedia({ audio: true })
     .then(mediaStream => {
-      const tracks = mediaStream.getTracks();
-      assert_greater_than(tracks.length, 0,
-        'Expect getUserMedia to return at least one audio track');
-
-      const track = tracks[0];
+      const [track] = mediaStream.getTracks();
       const sender = pc.addTrack(track, mediaStream);
 
       const pc2 = new RTCPeerConnection();
@@ -119,11 +111,7 @@
 
     return navigator.mediaDevices.getUserMedia({ audio: true })
     .then(mediaStream => {
-      const tracks = mediaStream.getTracks();
-      assert_greater_than(tracks.length, 0,
-        'Expect getUserMedia to return at least one audio track');
-
-      const track = tracks[0];
+      const [track] = mediaStream.getTracks();
       const sender = pc.addTrack(track, mediaStream);
 
       const pc2 = new RTCPeerConnection();
@@ -158,11 +146,7 @@
 
     return navigator.mediaDevices.getUserMedia({ audio: true })
     .then(mediaStream => {
-      const tracks = mediaStream.getTracks();
-      assert_greater_than(tracks.length, 0,
-        'Expect getUserMedia to return at least one audio track');
-
-      const track = tracks[0];
+      const [track] = mediaStream.getTracks();
       const sender = pc.addTrack(track, mediaStream);
 
       assert_equals(sender.track, track);

third_party/WebKit/LayoutTests/external/wpt/webrtc/interfaces.https.html

@@ -81,11 +81,7 @@
   function asyncInitMediaStreamTrack() {
     return navigator.mediaDevices.getUserMedia({ audio: true })
     .then(mediaStream => {
-      const tracks = mediaStream.getTracks();
-      assert_greater_than(tracks.length, 0,
-        'Expect media stream to have at least one track');
-
-      idlTestObjects.mediaStreamTrack = tracks[0];
+      idlTestObjects.mediaStreamTrack = mediaStream.getTracks()[0];
     });
   }