This allows ManifestFetcher to both execute the initial
manifest load and be plugged into an ExoPlayer ChunkSource,
where it can be used for repeated manfiest refreshes during
live playback.
2. Common interface for manifest parsers.
- This effectively moves the common interface from the Fetcher level
(i.e. ManifestFetcher) to the Parser level (i.e. ManifestParser).
- The motivation here is to allow the implementation of components that
can work with a generic ManifestParser implementation.
Since we have a Format class as well, it's very confusing that
FormatHolder actually holds a MediaFormat. I think it's quite
likely that Format will need promoting into the root package as
part of the HLS work, which will make this even more confusing
(although it is possible that for HLS we'll define yet another
Format class, if it turns out we need significantly different
fields).
Note - I deliberately avoided renaming the formatHolder
args/params, because they're not particularly ambiguous and
because it introduces some ugly line breaks.
- Allow the content type of an adaptation set to be inferred
from the mimeTypes of the contained representations.
- Ensure the contained mimeTypes are consistent with one
another, and with the adaptation set.
Ref: Issue #2
