Regression: Subtitles are not changed when they're invisible

[yairans]

NOTE: For bugs, if you delete this template, we will send it again and ask you to fill it out.

Have you read the FAQ and checked for duplicate open issues?:

What version of Shaka Player are you using?: 2.3.2

Can you reproduce the issue with our latest release version?: yes

Are you using the demo app or your own custom app?: demo

What browser and OS are you using?: Chrome 64/macOS High Sierra

What are the manifest and license server URIs?:
https://storage.googleapis.com/shaka-demo-assets/angel-one/dash.mpd

What did you do?
Load
Turn on the CC button
Verify the text language is English
Turn off the CC button
Switch to another text language (French for example)
Turn on the CC button
What did you expect to happen?
The captions should be in French
What actually happened?
The captions are still in English

[theodab]

Reproduced. I'll look into it, thanks for the report.

[willianpc]

Seems to work fine when rolling back a change at player.js#onChooseStreams_ at the return statement.
Not sure what kind of problems this can bring though. From my tests so far, no side effects were found.

  // Don't fire a tracks-changed event since we aren't inside the new Period
  // yet.
  // Don't initialize with text stream if the caption is not visible.
  // if (this.isTextTrackVisible()) {
  //   return { variant: chosenVariant, text: chosenTextStream };
  // } else {
  //   return { variant: chosenVariant, text: null };
  // }
  return { variant: chosenVariant, text: chosenTextStream };

[theodab]

I have a CL out for this. The problem was that we are trying to unload the text stream when captions are disabled, but we forgot to actually unload the text data from MediaSource. In that asset the entire video's captions are a single segment, so it never loads new text data.

[joeyparrish]

Cherry-picked for v2.3.3.