SDK / exoplayer

The ID_SEGMENT can only be read once, as seeing the element a second time is
assumed to indicate that the file contains multiple segment elements (which is
not supported).

This change allows the element to be read twice if it is at the same position,
so that retrying loading from the start can succeed.

This ensures FLAG_END_OF_STREAM doesn't get permanently stuck.

1. Workaround for decoders that fail to handle the END_OF_STREAM flag.
2. Revert processing of final output buffer if it's non-empty. This
   introduced another bug (#596)

Reverts: b88012f5
Issue: #417
Issue: #596

SubtitleLayout no longer trigger re-layouts of the view hierarchy.
Instead, the SubtitleLayout just invalidates itself. This is made
possible by making SubtitleLayout a regular View that draws each Cue
directly onto the canvas, rather than having SubtitleLayout be a
ViewGroup with a child View for each Cue.

The SubtitleLayout is now properly aligned with the surface.
This means the subtitles remain on top of the video in portrait
mode, rather than being huge and below it.

Handling of this constant is already in place everywhere, this
just documents that its use is allowed.

Avoid using the VP8 decoder on Samsung Galaxy S4 Mini.
Issue: #548

Avoid using the MP3 decoder on Sony Xperia Z/API level 16.
Issue: #377

Issue: #585

Issue: #576

Prior to this change, there was a bug where playback would
fail with the following steps:

1. Start playback.
2. Pause playback.
3. Disable all renderers.
4. Enable at least one renderer.
5. Resume playback.

The new logic assumes that an input format change will be
followed by an output format change, but I think this is
pretty much guaranteed. If this weren't to happen then the
new pixel aspect ratio wont be picked up, but I think it's
extremely unlikely (it would require the format to stay
exactly the same except for the pixel aspect ratio, which
would be bizarre).

This makes it easier to add an extension for adjusting
audio playback rate.

Issue: #417

1. An optional U+FEFF BYTE ORDER MARK (BOM) character.
2. The string "WEBVTT".
3. Optionally, either a U+0020 SPACE character or a U+0009 CHARACTER
   TABULATION (tab) character followed by any number of characters that
   are not U+000A LINE FEED (LF) or U+000D CARRIAGE RETURN (CR) characters.
4. Exactly one WebVTT line terminators to terminate the line with the file
   magic and separate it from the rest of the body.

Issue: #580

This is useful for reproducibility in playback tests.

Improve Mp4Extractor test.

Add support for Xiph lacing in Matroska files.

Add support for EBML lacing in Matroska files.

Handle the initial sticky intent for HDMI audio plug.