Try to remove the requirement of signing the app with the platform key

Currently, Seedvault needs to be signed with the platform key to work (the same key the OS is signed with). It could be possible to get rid of this requirement. For example, by providing an alternative UI path to select storage when the MANAGE_DOCUMENTS permission was not granted.

If that works, we can use a hidden-api-whitelist configuration instead of signing with platform cert to continue to access the hidden APIs we need for backup: https://github.com/LineageOS/android_vendor_lineage/commit/dab1569b810eb3e1185b1f6521fa159fce57095d example whitelist file

Tasks:

• detect at runtime if permission was granted and choose backup/restore storage UI path accordingly
• implement different UI storage choosing path for backup
• implement different UI storage choosing path for restore
  • ensure the user can re-choose a storage location if no backups are found at chosen location
  • give option to install NextCloud (if needed)

[grote]

I made a first attempt at https://github.com/grote/backup/tree/no-platform-key please let me know if this still crashes due to access to MANAGE_DOCUMENTS.

[grote]

we could test with the publicly available R betas and see if it works.

@chirayudesai maybe just for this issue, we should test with Android 10 first, because the 11 betas might break other things we don’t know about, yet.