add Accessibility in the Controlbar (Dash-Industry-Forum#4791)

* add Accessibility in the Controlbar

* group Accessibility with Role

* Minor refactoring

---------

Co-authored-by: [email protected] <[email protected]>
Co-authored-by: Daniel Silhavy <[email protected]>

Author: 3 people

contrib/akamai/controlbar/ControlBar.js

@@ -580,10 +580,14 @@ var ControlBar = function (dashjsMediaPlayer, displayUTCTimeCodes) {
                         info += 'Language - ' + element.lang + ' ';
                     }
 
-                    if (element.roles[0]) {
+                    if (element.roles && element.roles.length > 0) {
                         info += '- Role: ' + element.roles[0].value + ' ';
                     }
 
+                    if (element.accessibility && element.accessibility.length > 0) {
+                        info += '- Accessibility: ' + element.accessibility[0].value + ' ';
+                    }
+
                     if (element.codec) {
                         info += '- Codec: ' + element.codec + ' ';
                     }