[Graphics General] Save scene pop up does not close after clicking on Don't Save button on changing Graphics API.

Save scene pop up does not close after clicking on Don't Save button on changing Graphics API.

Steps to repro:
1. Create a new Project > Create Cube.
2. File > Build Settings > Player Settings.
3. Uncheck Auto Graphics API for Windows.
4. Select Direct3D12 and drag it to the top in the list.
5. Restart the editor > Click on Don't Save button.
6. Click on Cancel Button Or Close button.

Actual Result:
Save scene pop up does not close.

Expected Result:
Save scene pop up should be closed.

Reproducible in:
2019.3.0a8.

Working fine in:
2019.3.0a7, 2019.2.0b8.