How to detect switching between users

I have a service running in foreground mode and I'd like to detect switching between user sessions on tablets running Android 4.2 or above.

Is there any broadcast receiver I can register to get notified?

I have noticed that Google Music stops the music playback as soon as another user session is chosen on the lock screen. How does it detect the switch?

ANSWER EXPLAINED

Thanks @CommonsWare for the correct answer. I will explain a bit more how to detect a user switch.

First be aware that the documentation explicitly says that receivers must be registered through Context.registerReceiver. Therefore do something like:

UserSwitchReceiver receiver = new UserSwitchReceiver();
IntentFilter filter = new IntentFilter();
filter.addAction( Intent.ACTION_USER_BACKGROUND );
filter.addAction( Intent.ACTION_USER_FOREGROUND );
registerReceiver( receiver, filter );

Then in the receiver you can also retrieve the user id. Here is a small snippet:

public class UserSwitchReceiver extends BroadcastReceiver {

private static final String TAG = "UserSwitchReceiver";

    @Override
    public void onReceive(Context context, Intent intent) 
    {
        boolean userSentBackground = intent.getAction().equals( Intent.ACTION_USER_BACKGROUND );
        boolean userSentForeground = intent.getAction().equals( Intent.ACTION_USER_FOREGROUND );
        Log.d( TAG, "Switch received. User sent background = " + userSentBackground + "; User sent foreground = " + userSentForeground + ";" );

        int user = intent.getExtras().getInt( "android.intent.extra.user_handle" );
        Log.d( TAG, "user = " + user );
    }
}