Immediately switch audio tracks if different role selected

Previously, selecting a new audio track with selectAudioLanguage(), with
the same language but different role, would only set the variants to
switch to for ABR, but wouldn't actually switch to any of those variants
at the moment of selection due to a bug in chooseStreams_(), which was
still looking at only audio language as a differentiating mechanism.
This change honors the role as well, so that a switch to the correct
variants immediately happens.

Closes shaka-project#948

lib/player.js

@@ -29,6 +29,7 @@ goog.require('shaka.media.SegmentReference');
 goog.require('shaka.media.StreamingEngine');
 goog.require('shaka.net.NetworkingEngine');
 goog.require('shaka.text.SimpleTextDisplayer');
+goog.require('shaka.util.ArrayUtils');
 goog.require('shaka.util.CancelableChain');
 goog.require('shaka.util.ConfigUtils');
 goog.require('shaka.util.Error');
@@ -2327,7 +2328,7 @@ shaka.Player.prototype.chooseStreams_ =
   }
 
   // Check if any of the active streams is no longer available
-  // or is using the wrong language.
+  // or is using the wrong language/role.
   var activeStreams = this.streamingEngine_.getActiveStreams();
   // activePeriod may reasonably be null before StreamingEngine is streaming.
   var activePeriod = this.streamingEngine_.getActivePeriod();
@@ -2346,7 +2347,9 @@ shaka.Player.prototype.chooseStreams_ =
     for (var type in activeStreams) {
       var stream = activeStreams[type];
       if (stream.type == ContentType.AUDIO &&
-          stream.language != variants[0].language) {
+          (stream.language != variants[0].language ||
+          !shaka.util.ArrayUtils.equal(stream.roles,
+              variants[0].audio.roles))) {
         needsUpdate.push(type);
       } else if (stream.type == ContentType.TEXT && textStreams.length > 0 &&
                  stream.language != textStreams[0].language) {

test/player_unit.js

@@ -1033,7 +1033,7 @@ describe('Player', function() {
           .addVariant(3)
             .bandwidth(200)
             .language('en')
-            .addAudio(2).bandwidth(100)
+            .addAudio(2).bandwidth(100).roles(['secondary'])
             .addVideo(4).bandwidth(100).size(100, 200)
             .frameRate(1000000 / 42000)
           .addVariant(4)
@@ -1122,7 +1122,7 @@ describe('Player', function() {
           audioCodec: 'mp4a.40.2',
           videoCodec: 'avc1.4d401f',
           primary: false,
-          roles: [],
+          roles: ['secondary'],
           videoId: 4,
           audioId: 2,
           channelsCount: null,
@@ -1145,7 +1145,7 @@ describe('Player', function() {
           audioCodec: 'mp4a.40.2',
           videoCodec: 'avc1.4d401f',
           primary: false,
-          roles: [],
+          roles: ['secondary'],
           videoId: 5,
           audioId: 2,
           channelsCount: null,
@@ -1285,6 +1285,25 @@ describe('Player', function() {
               ContentType.AUDIO, variant2.audio, false);
         });
 
+    it('switches audio if tracks have different roles ', function() {
+          chooseStreams();
+          canSwitch();
+
+          var period = manifest.periods[0];
+          var variant1 = period.variants[0];
+          var variant2 = period.variants[2];
+          expect(shaka.util.ArrayUtils.equal(
+            variant1.audio.roles, variant2.audio.roles)).toBe(false);
+
+          player.selectVariantTrack(variantTracks[0]);
+          streamingEngine.switch.calls.reset();
+
+          player.selectVariantTrack(variantTracks[2]);
+
+          expect(streamingEngine.switch).toHaveBeenCalledWith(
+              ContentType.AUDIO, variant2.audio, false);
+        });
+
     it('doesn\'t switch video if old and new variants ' +
        'have the same video track', function() {
           chooseStreams();