Merge "[Media TTT] Refactor media states to use an enum instead of sealed...

Merge "[Media TTT] Refactor media states to use an enum instead of sealed classes." into tm-dev am: bb1a04a5

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/17070719

Change-Id: I8a283402d1490a360813b4b1e269056d8a8ba367