(This is a merge of http://go/wvgerrit/95003.)
To reduce the number of OEMCrypto calls on the decrypt path, the maximum
subsample size will now be cached after the first call to retrieve it.
Bug: 150018606
Test: Android Unit Tests
Test: CE CDM Unit Tests
Test: ExoPlayer high-bitrate playback on OEC v15
Change-Id: I0b5d38d8a082c0a127d2a47f112b76c64085bddb