SDK / exoplayer

And delete things that we're parsing but don't use from TrackElement.

- This makes HLS consistent with Chunk/ExtractorSampleSource.
- It needs to be consistent for WebVTT in HLS.
- Also trim the allocator when done.

- Have TsExtractor report a SeekMap to the output.
- Implement TsExtractor.reset to reset extractor state.
- Add 1x sample.

Play movies has an Allocator that attempts to allocate a single
huge byte[] up front to minimize the risk of GC pauses. This abstraction
will be required to keep that when updating them to the new Exo.

Making Representation and TrackElement extend Format will simplify
this further (TBC whether this is a good idea!).

Issue: #393

This is in preparation for removing bitrate from MediaFormat.

VP8 can be decoded by MediaCodec (since very early versions of android). Now that we want WebmExtractor to be general purpose, adding VP8 makes sense as it is a common use case.

This CL adds support for parsing BlockGroup elements for all
codecs (not just opus). It also adds a test to verify the new
behavior.

This is in preparation for adding support for AC-3 in HLS.

Also parse E-AC-3 boxes.

Refactor the extractor tests to enable testing of multi track Webm support.

Github Issue: #363

This CL adds support for WebM files which have Cues present at the end of the file (i.e.) after Clusters. The file referenced in the bug can now be played back using the demo app. It adds a new flag to WebmExtractor which should be set to true only when being used through ExtractorSampleSource. All others (e.g. DASH) should not set it.

Reference file: http://demos.webmproject.org/exoplayer/glass_vp9_vorbis_cues_at_end.webm

I've found myself doing this a couple of times during local
debugging. It's harmless to have it public, and seems pretty
useful for debugging inside of the mp4 package.

This is in preparation for adding support for AC-3 in HLS.

Also parse E-AC-3 boxes.

fix for issue #403

Seems a little hacky to define this in Track, but there doesn't seem to
be a particularly nice alternative.

Issue: #406

I was hoping not to avoid this, but in the case of a parsing
failure during preparation we keep retrying forever!

Using a file:// URL for loading an HLS stream (for testing) would fail due to
casting the connection to an HttpURLConnection in DefaultHttpDataSource.

This change makes UriDataSource an interface for objects that are DataSources
with URIs. That allows for reading manifests for HLS using just a UriDataSource
rather than an HttpDataSource (URLs in the playlist are relative to the data
source's URL so the getUri method is needed).

Github Issue: #363

On retrying loading a chunk, the state of the extractor was reset due to a call
to seek(). Prevent this call by only calling init() if no bytes were loaded.

Also make the DefaultExtractorInput use the loading position not the original
stream position so that its getPosition() method returns offsets relative to
the start of the stream, which fixes a bug where the chunk index offsets would
be relative to the wrong position if there was a retry while loading the chunk.

BaseChunkSampleSourceEventListener.onLoadCompleted.