This is written in such a way that it can safely handle task items in the
old format so long as the DNS writer to use for the given TLD is unambiguous
(which it is for now, until we allow multiple DNS writers to be configured).
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=162293412
This is one of several CLs in a sequence for allowing per-TLD DNS
implementations.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=129445641