Pass crypto source data using a shared buffer

MediaCodec was using a binder transaction buffer
to pass encryption source data for protected content.
On some 4K content, the max binder transaction buffer
size was being exceeded.  This change uses a shared
buffer for the encryption source data instead of a
binder transaction buffer, which avoids the problem and
may be more efficient.

bug: 20027687
Change-Id: I36a24ebf600d7e1064b78e48b167fdc29b2c65e9