Currently, if the publisher does not provide a label to identify a track, the player will display "Unknown" and "Off" as the available tracks when the user selects the CC button.

After discussion with UX, the video player should be changed as follows:

1. If there is only one caption or subtitle track, the CC button should act as a toggle (on/off).  The button graphic already indicates the On/Off state.

2. If there are multiple tracks, the CC button should display a list, and:
a. use the developer provided label for each track where available (existing behavior);
b. otherwise, use the developer provided language tag if available;
c. otherwise, display "Track 1", "Track 2" (instead of "Unknown")

Note that tracks (or 'label' properties) may be added or removed at any time through JS, and the UI should keep in sync as changes are made.

Eng owner: mlamouri@
Product owner: johnpallett@