SDK / exoplayer

The doc can be improved by enumerating and linking all possible values from
the interface doc.

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Created by MOE: https://github.com/google/moe
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Apps targeting P or later now must request this permission in order to
use foreground services.

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This happens rarely and SimpleCache can continue fine.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=209758330

Also remove NonNull, since we assume NonNull by default. Except
where explicitly overriding a method with NonNull annotated args,
in which case we're still expected to use it.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=209758204

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Created by MOE: https://github.com/google/moe
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If available parse and use spherical metadata:
https://github.com/google/spatial-media/blob/master/docs/spherical-video-v2-rfc.md

RELNOTES=true

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Created by MOE: https://github.com/google/moe
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Created by MOE: https://github.com/google/moe
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The previous change was too aggressive as it would clear future ad breaks.

Still clear the pending content position so the real content position is
reported after an empty ad break.

Issue: #4681
Issue: #4622

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=209752306

Some tests were flaky because of the PlayUntilPosition action which called
player.setPlayWhenReady from the wrong thread. Also fixed some other misc
flakiness.

ExoPlayerTest seems to be non-flaky now (tested with 10000 runs).

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=209743076

The options menu is not available on Android TV, which triggers a
null pointer exception whenever a sample is chosen.

This CL is a temporary fix until we rework the UI to not use
an options menu.

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Created by MOE: https://github.com/google/moe
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Issue:#4666

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Created by MOE: https://github.com/google/moe
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They don't need to be accessed publicly and are can be moved into the
respective chunk sources. This is the same structure used for Dash.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=209507217

The MediaPeriodId with index is only properly defined together with a
timeline containing the index. Changing it to the period uid allows to use
the MediaPeriodId independent of the corresponding timeline.

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Created by MOE: https://github.com/google/moe
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The reason for the change is that variable substititution requires
master playlist variable definitions at the moment of parsing.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=208997963

Issue: https://github.com/google/ExoPlayer/issues/4493

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Created by MOE: https://github.com/google/moe
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feat(playlist): remove MediaSource range

WebvttExtractor: make public to allow create custom HlsExtractorFactory outside of library

#4304 - Add option to show buffering view when setPlayWhenReady is false

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Issue: #4532

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MOE_MIGRATED_REVID=208968252

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Created by MOE: https://github.com/google/moe
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When playing a playlist where the exact maximum input size is known from the
container for each item, it may be necessary to recreate the decoder to increase
its maximum input buffer size at the point of transitioning from one item to the
next, which can make transitions non-seamless.

Scale up the initial video decoder maximum input size so playlist item
transitions with small increases in maximum sample size don't require
reinitialization.

Issue: #4510

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