Merge from master branch of Widevine repo of http://go/wvgerrit/66070 Merge from oemcrypto-v15 branch of Widevine repo of http://go/wvgerrit/63662 To make the threading model more clear, CopyBuffer is now a session function. This means we need to pass in which session the current thread locks. Test: unit tests. Test: tested as part of http://go/ag/5501993 Bug: 113680369 Change-Id: I2fdd2cfcaab99f3793950b3845941463675f5e4c