This will help with removing selection factories from
SelectionOverride. It doesn't seem worth the effort to
have this togglable and in the UI of our demo app.
This change will also:
- Help to move TrackSelectionHelper into the UI module,
since it removes the part that's obviously debug-only.
- Make it possible to specify the ABR algorithm for each
sample, which might be nice as we start implementing
more of them.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=192760196
