unlock method
Unlocks the camera to allow another process to access it.
Normally, the camera is locked to the process with an active Camera object until release is called. To allow rapid handoff between processes, you can call this method to release the camera temporarily for another process to use; once the other process is done you can call reconnect to reclaim the camera.
This must be done before calling MediaRecorder.setCamera. This cannot be called after recording starts.
If you are not recording video, you probably do not need this method.
Throws PlatformException if the camera cannot be unlocked.
Implementation
Future<void> unlock() {
return _channel.$unlock(this);
}