This CL removes the domain to origin scoped migration code added for
crbug.com/604612. The pref used for the migration is now cleared on
startup to ensure that dead data is not retained.
Reviewed-on: https://chromium-review.googlesource.com/765554Reviewed-by: Timothy Loh <firstname.lastname@example.org>
Reviewed-by: Martin Šrámek <email@example.com>
Commit-Queue: Dominick Ng <firstname.lastname@example.org>