EMSG boxes are not being completely parsed

[chrisfillmore]

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

What version of Shaka Player are you using?:
2.3.3

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

Can you reproduce the issue with the latest code from master?:
Did not check

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

If custom app, can you reproduce the issue using our demo app?:
Unknown. Does any demo content contain emsg boxes?

What browser and OS are you using?:
Chrome on macOS

What are the manifest and license server URIs?:
I could potentially provide a demo app to reproduce, if required. But I think you can follow the thread through the code to see the issue.

What did you do?
Attempt to play one of our live DAI streams which contains EMSG boxes.

What did you expect to happen?
All EMSG boxes should get parsed and published.

What actually happened?
We only see one EMSG box published (out of three, I believe) per segment.

We just upgraded from 2.2.8 to 2.3.3. We now have a problem with emsg boxes not being parsed/published. It looks like the bug was introduced in a93455a. Specifically, StreamingEngine#parseEMSG_ now does:

box.parser.stop();

...and Mp4Parser#parse now checks if !this.done_ while parsing:

while (reader.hasMoreData() && !this.done_) {
  this.parseNext(0, reader, opt_partialOkay);
}

Since parseEMSG_ is passed to Mp4Parser#fullBox as the definition, and this is invoked each time Mp4Parser#parseNext is called, the parser stops parsing after the first emsg box.

This was introduced in v2.3.0 but I don't see mention of #1106 in the release notes.

[chrisfillmore]

Thanks @TheModMaker!

[joeyparrish]

Fix cherry-picked for v2.3.4.