Remove unused VariationsSeedExpiry enum.

It now lives in variations_field_trial_creator.cc, so this copy
is not used.

Bug: none
Change-Id: I8bccc220e29b550a5b45ebd95aa557f3cf2ac64b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2305112
Auto-Submit: Alexei Svitkine <asvitkine@chromium.org>
Commit-Queue: Steven Holte <holte@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791459}

components/variations/service/variations_service.cc

@@ -153,13 +153,6 @@ void RecordRequestsAllowedHistogram(ResourceRequestsAllowedState state) {
                             RESOURCE_REQUESTS_ALLOWED_ENUM_SIZE);
 }
 
-enum VariationsSeedExpiry {
-  VARIATIONS_SEED_EXPIRY_NOT_EXPIRED,
-  VARIATIONS_SEED_EXPIRY_FETCH_TIME_MISSING,
-  VARIATIONS_SEED_EXPIRY_EXPIRED,
-  VARIATIONS_SEED_EXPIRY_ENUM_SIZE,
-};
-
 // Converts ResourceRequestAllowedNotifier::State to the corresponding
 // ResourceRequestsAllowedState value.
 ResourceRequestsAllowedState ResourceRequestStateToHistogramValue(