Get method documentation [Android Documentation]

Gets the controller which should be receiving media key and volume events while this activity is in the foreground.

Set method documentation [Android Documentation]

Sets a Android.Media.Session.MediaController to send media keys and volume changes to. The controller will be tied to the window of this Activity. Media key and volume events which are received while the Activity is in the foreground will be forwarded to the controller and used to invoke transport controls or adjust the volume. This may be used instead of or in addition to Activity.VolumeControlStream to affect a specific session instead of a specific stream. It is not guaranteed that the hardware volume controls will always change this session's volume (for example, if a call is in progress, its stream's volume may be changed instead). To reset back to the default use null as the controller.