When a loaded DASH manifest is invalid (either some periods were removed
illegally, or a manifest for a live event is stale), we will retry using 1
logic:
- Retry loading with back-off up-to a limit.
- Throw a DashManifestExpiredException() if we exceed retry limit.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182770028

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182754993

Also disable use of dummy surface for devices that require the
workaround. It's only useful in the case that we can use
setOutputSurfaceWorkaround, so if it's disabled the dummy surface
has no purpose (it actually makes things worse by consuming past
the key-frame prior to the current position, which doesn't happen
if you have no surface at all).

Issue: #3724

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182750068

This fixes a very specific case where the data read has non-cached gaps
and a read-only CDS switches to read from upstream in a gap then the
cached data is deleted. When the CDS reaches the end of the gap, it
tries to open the next source. As there is no cached data, it tries to
continue with the already opened upstream data source but as it reached
end of the gap range, the code starts looping.

Also fixes infinite lock which occurs when in the previous case CDS isn't
readonly. It locks the content while filling the gap in the cache. At the
end of the gap, as the following data is deleted it tries to lock the
content for writing but the content is already locked by itself.

The last fix is preventing removal of CachedContent entry from
CachedContentIndex while associated key is locked.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182595426

Some tests in ExoPlayerTest issue commands to the player from the test thread
while the player is actively playing media (playWhenReady=true). Due to the
indeterminate time taken to enqueue the commands on the playback thread, they
may arrive when the player already proceeded to another window or finished
playback.

To ensure the tests are always deterministic, this change pauses playback in
the tests where this may happen before issuing the commands.
Also, for tests where we need to wait for a new window before issuing the
next command, a new action is added which allows to play until a specified
position.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182535096

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182534505

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182533415

- Get handling of "stale" and "out of sync" manifests so
  they're right next to each other (to be merged)
- Move startLoadingManifest to be next to the methods that
  schedule it, and actually start loading stuff.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182530683

As soon as the seek gets acknowledged by EPII, EPI returns the actual position
from the playback info again which is set by EPII. Thus, EPII needs to update
the position to reflect the changes expected by EPI.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182515106

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182512582

- In IDLE, the button will now call a preparer. This allows
  removal of the separate retry button from the demo app.
- In ENDED, the button will seek back to the default position
  and play.
- Behavior is made consistent with LeanbackPlayerAdapter.

Issue: #3689

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182506855

When determining the next sample to load, the Mp4Extractor now takes
into account how far one stream is reading ahead of the others.
If one stream is reading ahead more than a threshold (default: 10 seconds),
the extractor continues reading the other stream even though it needs
to reload the source at a new position.

GitHub:#3481
GitHub:#3214
GitHub:#3670

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182504396

Add SAMPLE-AES-CTR, which replaces SAMPLE-AES-CENC per latest spefication: https://storage.googleapis.com/wvdocs/Widevine_DRM_HLS.pdf.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182407790

It seems good to have EventLogger available from the library.
In particular because when app developers use it and then
submit bug reports, it makes it much easier to work out what
happened. It will also allow EventLogger to be used across
our (now multiple) demo apps.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182389407

This gets rid of the manual tracking of this queue with reading, playing,
and loading period holders. Still keeping these names for queue access methods.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182378944

Also sanitize naming (PlayerView/PlayerControlView).

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182364487

Issue:#3622

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182363243

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182261649

This was broken by []

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182206548

Issue:#3632

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182202289

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182183184

This solves the problem of having dense tracks' ids change.
For example, if the available variants offer both HEVC and AVC video
tracks, all video samples will map to the same sample queue even if
IDs don't match.

Issue:#3653

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182070486

Issue:#3653

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182064250

This avoids issues that can arise due to slight discrepancies between
chunk start times (obtained from the manifest of segment index) and
the timestamps of the samples contained within those chunks.

Issue: #2882

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182054959

This is a Scheduler implementation which uses Firebase JobDispatcher.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182051350

For live streaming, there are several types of DASH `emsg' events that directly
target the player. These events can signal whether the manifest is expired, or
the live streaming has ended, and should be handle directly within the player.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182034591

Android NDK r9 in [] is deprecated (see []

Update the ExoPlayer flac extensions to use android_jni_library.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182017669

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=181970955

This allows listeners to get notified of any change to the embedded tracks.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=181969023

ChunkSampleStream.seekToUs assumes that if we can seek within the
primary sample queue, we can also seek within the embedded queues.
This assumption can be violated fairly easily if discardBuffer is
called with toKeyframe=true, since this can cause samples to be
discarded from the embedded queues within the period for which a
seek in the primary sample queue will succeed. This change fixes
the issue.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=181965902

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=181962471

PGS subtitle decoding support

minimal fix to support NDK r16

Issue: #3703

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=181947101

These haven't been included in the recent changes but can be reported as
soon as the first sample of each stream is read.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=181753141

We added the other callbacks some time ago, but didn't include onLoadStarted.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=181743764

This it to distinguish between actual period transitions and the
transitions occuring to and from ads within one timeline period.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=181606023

Issue: #3008

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=181455340

Also fixed some other Cache related javadoc.

Issue: #3374

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=181440687