Add support for multiple roles to DASH parser.

DASH parser used to assume representation can only have one role.
However that's not true in case of text representations that can
have both role=main and role=caption/subtitle.

Closes #500

Change-Id: I1b6a494347a0b86211b6982416e444c020b1eeb0

lib/dash/dash_parser.js

@@ -716,19 +716,19 @@ shaka.dash.DashParser.prototype.parseAdaptationSet_ = function(context, elem) {
   context.adaptationSet = this.createFrame_(elem, context.period, null);
 
   var main = false;
-  var role = XmlUtils.findChild(elem, 'Role');
+  var roles = XmlUtils.findChildren(elem, 'Role');
 
   // Default kind for text streams is 'subtitle' if unspecified in the manifest.
   var kind = undefined;
   if (context.adaptationSet.contentType == 'text') kind = 'subtitle';
 
-  if (role) {
-    var scheme = role.getAttribute('schemeIdUri');
+  for (var i = 0; i < roles.length; i++) {
+    var scheme = roles[i].getAttribute('schemeIdUri');
     if (scheme == null || scheme == 'urn:mpeg:dash:role:2011') {
       // These only apply for the given scheme, but allow them to be specified
       // if there is no scheme specified.
       // See: DASH section 5.8.5.5
-      var value = role.getAttribute('value');
+      var value = roles[i].getAttribute('value');
       switch (value) {
         case 'main':
           main = true;

test/dash/dash_parser_manifest_unit.js

@@ -114,6 +114,7 @@ describe('DashParser.Manifest', function() {
           '    <AdaptationSet mimeType="text/vtt" codecs="mp4a.40.29"',
           '        lang="es">',
           '      <Role value="caption" />',
+          '      <Role value="main" />',
           '      <Representation bandwidth="100" />',
           '    </AdaptationSet>',
           '    <AdaptationSet mimeType="audio/mp4">',
@@ -145,6 +146,7 @@ describe('DashParser.Manifest', function() {
                 .size(576, 432)
             .addStreamSet('text')
               .language('es')
+              .primary()
               .addStream(jasmine.any(Number))
                 .anySegmentFunctions()
                 .anyInitSegment()