In some cases (deferred restore) the app data needs to be cleared even
if the app has implemented backup agent. As a quick fix introduce
PACKAGES_TO_CLEAR_DATA_BEFORE_FULL_RESTORE secure setting, which
transport can fill prior to restore.
Bug: 69069240
Test: adb shell settings put secure packages_to_clear_data_before_full_restore com.google.android.apps.nexuslauncher && adb shell bmgr restore com.google.android.apps.nexuslauncher
Change-Id: I2a4651365d9cf4747f32d2ba69312f54cd03d118
5b53875fdc