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This pull request fixes a subset of #5492 by saving the application
state when the `suspended` event is received on Android. This way, even
if the user exits the app and closes it manually right after changing
some state, it will be saved since `suspended` gets fired when the app
is exited. It does not fix the `on_exit` function not being fired - this
seems to be a winit bug (the `exiting` function in the winit application
handler trait is not called on exit). Once it gets fixed, it may be
possible to remove logic introduced by this PR (however, I am not sure
how it would handle the app being killed by the system when in the
background, that would have to be tested).
I've tested the logic by:
* Leaving from the app to the home screen, then killing it from the
"recent apps" menu
* Leaving from the app to the "recent apps" menu and killing it
* Restarting the device while the app was running
In all of these instances, the state was saved (the last one being a
pleasant surprise). It was tested on the repository mentioned in #5492
with my forked repository as the source for eframe (I unfortunately am
not able to test it in a larger project of mine due to dependence on
"3rd party" egui libraries (like egui_notify) which do not compile along
with the master branch of eframe (different versions of egui), but I
believe it should work in the same manner in all scenarios). Tests were
conducted on a Galaxy Tab S8 running Android 14, One UI 6.1.1.
CI passed on my fork.
* [x] I have followed the instructions in the PR template
93d2144294