Currently for a DASH ChunkSource that consists of multiple sub-streams, we
always use a CompositeSequenceableLoader, which only allows the furthest behind
loader or any loader that are behind current playback position to continue
loading.
This changes allow clients to have more flexibility when deciding the loading
strategy:
- They can construct a different kind of composite SequenceableLoader from
the sub-loaders, and use it by injecting a different CompositeSequeableLoaderFactory accordingly.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=176363870
0de57cbfae