The API Guide has it all wrong (really Google?). With Maps API v2 you do not need to enable a layer to show yourself, there is a simple call to the GoogleMaps instance you created with your map.
Google Documentation
The actual documentation that Google provides gives you your answer. You just need to
If you are using Kotlin
// map is a GoogleMap object
map.isMyLocationEnabled = true
If you are using Java
// map is a GoogleMap object
map.setMyLocationEnabled(true);
and watch the magic happen.
Just make sure that you have location permission and requested it at runtime on API Level 23 (M) or above