HLS code is implemented in the C ++ library, so you probably couldn't find it with GrepCode.
The library is called stagefright , and it is used by Java classes (MediaPlayer, etc.) and then uses other shared libraries to interact with hardware decoders.
You can find an overview of how it works on Android here .
And the source code for HLS, for which you can find the HLS-specific source code here and / or here .