While Unity shows splash screen, snap application's window to left/right. After splash screen, application shows full screen (full width) resolution.

Repro steps:
1. Create empty project with a script, which shows screen's width;
2. Build to Win Store Apps;
3. Launch the project and when splash screen appears, wait for a blink(if you didn't change splash logo). After a blink, snap application to left or right. Application should display screen's width as full screen's.