SDK / exoplayer

1. Pull up all subclasses of DownloadAction into DownloadAction
2. Add DownloaderFactory for Downloader instantiation, and DefaultDownloaderFactory
   to replace the instantiation logic being removed from the DownloadAction
   subclasses.

This change will upgrade existing action files gracefully (i.e. it does not
lose compatibility with the existing offline implementation, other than some
minor breaking changes to the API).

TODOs:

1. Move test methods from the XDownloadActionTest classes into DownloadActionTest.
   This will be done in a subsequent CL. There's a lot of consolidation that can
   be done here, including de-duplicating some of the test code added in this CL.
2. Look at merging DownloaderConstructorHelper into DefaultDownloaderFactory.
3. Use customCacheKey in DASH/HLS/SS Downloaders, for completeness.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=222258983

createTrackSelections decides whether to create an adaptive or a fixed track seletion to create.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=222231011

Forwarding the listeners to the notification update is meant to ensure we
only notify the listeners which were registered at the time the event happened

However, we currently just copy the reference to the actual list instead of
doing a deep copy of the listeners.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=222227735

This ensures that all callbacks use the same notification mechanism.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=222226913

The update is actually unrelated and putting it all in one large update
object complicates adding the same update mechanism for other values.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=222226825

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=222221294

Since version 17.0 play-services-ads requires specifying AD_MANAGER_APP=true in
AndroidManifest.xml, so add this in the IMA extension's manifest. See also
https://developers.google.com/ad-manager/mobile-ads-sdk/android/quick-start.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=222087771

WindowedTrackBitrateEstimator, uses future and past chunks in a window
of time to estimate track bitrate values.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=222065409

Interpret single-item audio stream edit lists as audio padding specification.  Use the information to strip out padding from decoded audio streams.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=221865861

Currently no path may be chosen if
minBufferUs == maxBufferUs == bufferedDurationUs.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=221639199

This is needed because the allocator can't be reused for example.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=221638233

This matches the binarySearchFloor method overload.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=221617114

- Increase the search window size to fix TS seeking for problematic
  media we've had provided to us.
- As per my comments on the issue, we should look at doing more here
  to better fix the problem. This will solve the worst of the
  immediate problem, however.
- The memory usage is non-trivial, particularly with the increased
  search window size. I've made the allocations only live whilst
  determining duration and seeking to address this. I've done the same
  for PS just for consistency.

Issue: #5097

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=221449988

The remaining work is to split Window.isDynamic so that it's
possible to represent a window that wont be appended to, but
may still be removed from.

Issue: #4780

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=221439220

This allows client code to run nullability checks.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=221437215

This is a precursor for fixing the ref'd issue. These classes are
well tested, so the tests passing should give you reasonable
confidence I didn't break anything :).

Issue: #5097

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=221435824

LegacyVideoTrackSelection is the previous implementation (unchanged).
VideoTrackSelection is rewritten to extend AdaptiveTrackSelection.

An experiment is added to allow use of the new VideoTrackSelection
implementation. It's envisaged that this transition will be more or
less a no-op change. The experiment flag is only in case of bugs
during roll-out, and will be removed with LegacyVideoTrackSelection
upon successful transition.

VideoTrackSelection also implements discard-on-trick-play-exit, which
was a TODO in the previous implementation.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=221153827

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=221078075

- This brings it in line with PlayerControlView. The play action is displayed
instead, and pressing it seeks to the default position of the current window.
- Do the same for MediaSessionConnector
- Add support for PlaybackPreparer consistent with PlayerControlView

Issue: #5072

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=221076008

Issue: #4915

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=221075615

The extension cannot be used without also using support-media-compat
(e.g. to instantiate a MediaSessionCompat). So it may as well be an
API dependency.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=221072128

This change also paves the way for splitting out functionality into a utility class.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=221070262

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=221065798

- Make MediaSessionConnector use a ControlDispatcher and add setControlDispatcher,
  setFastForwardIncrementMs and setRewindIncrementMs methods. This brings it in line
  with our other UI components, including PlayerControlView and
  PlayerNotificationManager.
- Collapsed DefaultPlaybackController into MediaSessionConnector, since I'm not
  sure there's a legitimate alternative implementation (note ControlDispatcher does
  provide some equivalent functionality e.g. to modify calls being made on the
  player).
- Pass the Player and ControlDispatcher to command receivers and custom actions,
  so they don't need their own references.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=220822082

- Simplify logic for dispatching to the rating callback
- Simplify CommandReceiver by removing getCommands. Simply calling
  receivers is simpler, and more flexible because it doesn't force
  implementations to define a static set of things that they handle
  up front.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=220788423

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=220643861

Issue: #4690

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=220640737

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=220616166

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=220592303

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=220529628

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=220500268

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=220470213

When in REPEAT_MODE_ONE, it's unlikely apps want next/previous methods
on the player to keep them in the same window. Music apps in particular
tend to implement next/previous functionality as though repeat mode were
off when in this mode (i.e. current song loops forever during playback,
but next/previous navigation still navigates to next/previous items).

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=220469655

Issue: #5065

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=220468285

- Make units of time clear for seeking
- Remove option to specify supported repeat modes in default
  playback controller. It doesn't seem useful, given we can't
  control what the session is sent.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=220464529

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=220461315

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=220447459

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=220432564

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=220323772

This fixes an issue where disabling audio focus handling
while audio focus is held would not release audio focus.

A new test was added for this situation.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=220316866