Cherry pick of http://go/ag/9326830
This is a merge of the full decrypt path testing CLs from the Widevine
repo: http://go/wvgerrit/q/topic:FDPT-subsamples
This is the Full Decrypt Path Testing application that can be used by
device makers to verify that OEMCrypto is correctly decrypting content
to secure buffers.
Testing: Ran App.
Bug: 113594822
Change-Id: Icbb1e2f2e762bac3cc1b7b20749922c14ea24449
