[Cleanup] Remove the obsolete variations_seed pref.

components/variations/pref_names.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/variations/pref_names.h"
 
 namespace variations {
 namespace prefs {
 
 // Base64-encoded compressed serialized form of the variations seed protobuf.
@@ skipping 14 matching lines @@
     "variations_permanent_consistency_country";
 
 // A serialized PermutedEntropyCache protobuf, used as a cache to avoid
 // recomputing permutations.
 const char kVariationsPermutedEntropyCache[] =
     "user_experience_metrics.permuted_entropy_cache";
 
 // String for the restrict parameter to be appended to the variations URL.
 const char kVariationsRestrictParameter[] = "variations_restrict_parameter";
 
-// Base64-encoded serialized form of the variations seed protobuf.
-const char kVariationsSeed[] = "variations_seed";
-
 // 64-bit integer serialization of the base::Time from the last seed received.
 const char kVariationsSeedDate[] = "variations_seed_date";
 
 // Digital signature of the binary variations seed data, base64-encoded.
 const char kVariationsSeedSignature[] = "variations_seed_signature";
 
 }  // namespace prefs
 }  // namespace metrics