android. egui_wgpu::winit: No window - clearing all surfaces

**Describe the bug**
Refocused activity doesn't find its window on winit, android.
I have app setting wallpaper of android background. after setting wallpaper with android foreground service, logcat is printing next error. app is freezing after this.

```
08-30 21:15:35.297 10605 10630 W BingtrayApp: egui_wgpu::winit: No window - clearing all surfaces
```

I have tried with foreground service and without it. the error is same.

**To Reproduce**
Steps to reproduce the behavior:
1. clone branch from https://github.com/nikescar/bingtray/tree/feat.eguibugreport
2. cd mobile && ./build.sh
3. adb install ./app/build/outputs/apk/debug/app-arm64-v8a-debug.apk
4. adb logcat -v time -s *:V > fullcat.log

**Expected behavior**
app should get refocus its previous states

**Additional context**
I have used egui 0.32 and android-activity, ndk-sys crates.
I have disabled persistent options might be related with it.

Start at the egui_wgpu::winit path that emits “No window - clearing all surfaces” and reproduce the problem with the mobile build, adb install, and logcat steps in the issue. Done means a refocused Android activity restores its previous state without the warning or app freeze.

Written by the indexing model from the issue text.