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It's possible to get a copy of an answer from previous matches and get the
same answer attached to a similar server-provided answer.  In the future,
we may decide that we want to have different answers attached to multiple
suggestions, but the current assumption is that there should only ever be
one suggestion with an answer.

BUG=

Review URL: https://codereview.chromium.org/603683004

Cr-Commit-Position: refs/heads/master@{#296818}