Fix that the PlaybackState position is not updated

This CL fixes the problem where MediaSessionCompat.getPlaybackState()
returns a playback state whose position is out-of-date.

Bug: 36861955
Test: Passed MediaControllerCompatTest in API 19-25, and Android O
Change-Id: Iaaecff6966be58658e80422ef9d9e351110f543d
Merged-In: Ib2897f8a5fd457260667f8cd85aa9d2435efd028
2 files changed