Fix dialog fragment setup, add regression test

[tobrun]

Closes #14025, next to fixing the sample code, I added a test to catch regressions.

[androideveloper]

Isn't this PR solving just sample usage case inside Activity? My case was a bit different. I'm using SupportMapFragment inside DialogFragment as a child fragment. I've attached demo project in the issue description.

[tobrun]

Isn't this PR solving just sample usage case inside Activity? My case was a bit different. I'm using SupportMapFragment inside DialogFragment as a child fragment. I've attached demo project in the issue description.

This PR is solving an issue with our DialogFragment sample. Adding a map to a dialogfragment is as shown in the code a bit of a hack. DialogFragment doesn't follow the lifecycle in a same way as normal fragment and that is why we have to override the dismiss callback to do our cleanup. See here. Adding such a setup might work for this inner child fragment setup but again, it's more of a hack as a solution.

[androideveloper]

But how to do a hack for my case? I'm using extending SupportMapFragment, all lifecycle methods are controlled by the fragment. Also I have tried to debug my dialog and all lifecycle methods of the fragment are called for my map fragment, but it still freezes in onDestroyView. Isn't this a bug of SupportMapFragment? I do the same setup for Google Maps and it works without any issues.

[androideveloper]

I have tried to implement hacky logic, but still the same. Even if I call of lifecycle methods of map inside my parent dialog fragment onDismiss, still the same freeze. What is causing freeze actually? It's somewhere inside native C++ code as I guess.

[tobrun]

@androideveloper found the root cause, added code similar to your setup as regression test in #14127

[androideveloper]

@tobrun Great! Thanks for the update! When are you planning to release it?