This will move ContentProtection element from Representation
to AdaptationSet.
Shaka Player already supports AdaptationSet switching
urn:mpeg:dash:adaptation-set-switching:2016;
ExoPlayer does not support it yet. Filed
https://github.com/google/ExoPlayer/issues/2431 to track the issue.
(ExoPlayer does not like having ContentProtection in Representation
anyway)
Closes b/34691105
Change-Id: I69d0a4d0e15a912a35c8b2686620419a28e4cc99