GitLab

Support the following features useful when decoding a compressed
 asset to PCM:
- GetDuration in SLPlayItf
- implemented SLMetadataExtractionItf on an AudioPlayer whose
  data sink is a buffer queue (i.e. it's a decoder)
- added support for 6 new metadata keys that can be queried
  through SLMetadataExtractionItf, which match the fields
  of the SLDataFormat_PCM structure.
Updated the decode sample code to use these features: the
 slesTestDecodeToBuffQueue app now displays:
- the number of channels
- the channel mask
- the sample size
- the container size
- the sample rate
- the format endianness

Change-Id: I3ca1e29828fd8c16c89da43a28df429c9cdef7af