It's fine for wallpaper backups to proceed even while the system uid
is considered to be doing something foreground-equivalent, since it's
in its own process and killing it won't interrupt the actual system
work.
Bug 30662562
Change-Id: I463c1ed221da17fbeb336b3be09d3b1ac47aca80
In addition, now that the full uncropped wallpaper image is being
backed up, we now handle that via the full-data backup path instead
of key/value. Restore still knows about legacy data that gets
delivered via the older key/value mechanism.
This change also has the effect of removing the size limitations
around wallpaper restore acceptance. Any size source imagery is
valid, as crop & scale are rerun in a device-appropriate way
after the restore.
Bug 25453848
Bug 25727875
Change-Id: Idc64a2eaab97a8ecc9d2b8ca5dc011f29cab324d
