Merge from Widevine repo of http://go/wvgerrit/68184
Please add comments to the original documents at http://go/oemcrypto
or http://go/wvdelta15.
Some unit tests will need to be updated. Those will be in a separate CL.
bug: 120795057 Full Decrypt Path Testing - change design
bug: 119688262 Full Decryption Path Test update section in go/wvdelta15
bug: 117898271 Corrections to Documentation
bug: 119881959 Remove shared license from documentation.
bug: 80540710 Document double call to OEMCrypto_DeactivateUsageEntry
Test: documentation and comment change only
Change-Id: I1ef35e15207d3dabea8329a1f05518370ec099e6
f42038d89a