The term "passthrough" was heavily overloaded. For clarity, split most
of its usage to different terms:
* codec "bypass": no MediaCodec is used
* "direct playback": no decoding occurs (but decryption may or may not)
* "decrypt only codec": a MediaCodec used only to decrypt, not decode
* "offload": playback to an offload AudioTrack.
* "passthrough" is now only used in the sense of playing encoded audio
* to a non offload AudioTrack.
PiperOrigin-RevId: 324984612
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