Add another overload to fetch by key ID directly, used by WebM.
Changed the one using PSSH data in favor of the entire PSSH box.
This also moves the Widevine proto to media base. Now, the
Widevine key source handles creating the Widevine specific PSSH
data.
Change-Id: I6f4633facad39207809ffbad970635d1f9d70983
- Also refactor decryptor management code out of mp4_media_parser.cc
- Move decryptor managment logic to DecryptorSource class to make it
available for webm as well
- Remove data_offset member from DecryptConfig which is not useful
- Add widevine_pssh_data.proto file
Closes#72
Change-Id: I1d32baf4013ebd3382b5372c7433fae5033a260e