fix(android): index of the selected track

[seyedmostafahasani]

Summary

Motivation

Changes

Test plan

[freeboub]

@seyedmostafahasani can you please describe your change please? Is it solving issue with specific content?

[seyedmostafahasani]

@freeboub in the sample app, we show a list of videos that a user can switch between. Before this change, the selected tracker was always the first item because trackIndex always passed 0. With this change, the correct selected track is always passed. Previously, if you ran the sample app, you could not see the subtitle for track BigBugBunny sideLoaded subtitles(last track in the sample app). However, now you can see it because the selected track is correct.