MediaSessionCompat: Introduce extra session binder and extra callback

There were several changes on MediaSession and MediaController for the new
APIs and bug fixes after API 21. In order to backport those changes, this
CL uses extra binders between MediaSessionCompat and MediaControllerCompat.

Bug: 31215547, Bug: 31248021, Bug: 31287025
Test: Tested the methods with Support4Demos on API 21 and API 22
Change-Id: Ia2a6fe5e7aa88b4b18db5819bd73ad7282a9c142
2 files changed