- Applications should generally use DefaultMediaSourceFactory,
or their own custom implementation if they need one. Having the
media2 extension implement its own version directly doesn't seem
that useful.
- Remove support for CallbackMediaItem. This type of MediaItem
doesn't go cross-process, and it seems like there would never
be a use case where an app would need to generate one locally.
If an app needs to provide data from a custom source, it should
hook into ExoPlayer's way of doing this (i.e., use a UriMediaItem
with a custom scheme, and inject a custom DataSource that can
handle this scheme).
PiperOrigin-RevId: 326914465
