SDK / exoplayer

Issue: #770

0 will crash. 1 is pointless.

....Except BACK and MENU, which only make sense if the the controller
is visible.

Issue #812

manifest.

Add onDrmSessionReady callback

This adds a callback for when DRM keys have been loaded.

Issue #804

Also include more Sony Xperia Z devices in the MP3 workaround.

Issue: #788

- Respect any padding set on SubtitleLayout.
- Allow specification of absolute, fractional and fractional-ignoring-padding
  text sizes.

Parse audioChannels only when on mpeg-dash

Only parse the @value as Int when the schemeIdUri is urn:mpeg:dash:23003:3:audio_channel_configuration:2011

Improve WebVTT parser according to WebVTT spec

Prevent ArrayIndexOutOfBoundsException when proguard is enabled

- Line parameter
  - Added support for value and line alignment attributes.
  - Support negative numbers when line is an absolute number (not a
percentage).
- Position parameter
  - Added support for value and position alignment attributes
- Added support for WebVTT comment blocks
- Percentage values now accept decimal numbers (as webvtt spec states)
- Added new WebVTT tests for testing all new implemented features

Issue: #437

- do not denormalize styles at parsing time but only put normalized style info
into TtmlNode tree. Resolve styles on demand when Cues are requested for a
given timeUs.
- create TtmlRenderUtil to have static render functions separate
- added unit test for TtmlRenderUtil
- adjusted testing strategy for unit test to check resolved style on Spannables after rendering

Issue: #791

Issue: #789

There is no guarantee codec names start with this prefix in >= L.

Issue: #782