Adds android.media.DataSource, which is modeled after its native namesake,
and a new method on MediaExtractor that lets apps specify their implementation
of a DataSource as the source of data for the extractor.
Change-Id: If1b169bd18d2691ebc4f8996494dfc8ee0894b6c
New API on MediaExtractor to retrieve a CryptoInfo structure where applicable.
Change-Id: I18edfc9ac56a4544c8f17cba24401b96dacbff7d
related-to-bug: 6275919