Steps to reproduce:
1. Download 1180242_repro.zip
2. Build project for UWP
3. Open generated Visual Solution and build player
4. Press 'SPACE BAR' to exit fullscreen
5. Adjust Player window aspect ratio
6. Press 'SPACE BAR' to enter fullscreen

Expected results: Re-entering fullscreen mode add black bars if the new aspect ratio doesn't match the monitor's aspect ratio (This is the way Standalone player resolves this issue)
Actual results: Re-entering fullscreen mode stretches the screen

Reproduced with: 2020.1.0a2, 2019.3.0b2, 2019.2.3f1, 2018.4.8f1, 2017.4.32f1

Note:
- Reproducible with Debug, Release, Master configuration and x64, x86 platforms