1. Make LeanbackPlayerAdapter use a ControlDispatcher. This
allows apps to suppress control events in some circumstances,
and is in-line with our mobile controls.
2. Misc simplifications and cleanup to LeanbackPlayerAdapter.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=166852816
- Have a single inner class for all listeners. This is inline
with what we do elsewhere in the library.
- Avoid repeated getCallback() calls within methods.
- Seek to default position from ended state, rather than 0.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=165603927