Fix MediaSessionManager.Callback to be called with the media button session

MediaSessionManager.Callback have been called with the previous media
button session instead of latest media button session.

Bug: 37998705
Test: Manual test (Avrcp leaves log fo the addressed player changes)
Change-Id: I57b0b88f68c70047474d0f0e3d10eac527eb57bd
2 files changed