[Metrics] Move CachingPermutedEntropyProvider into the variations component.

chrome/common/metrics/proto/permuted_entropy_cache.proto

Index: chrome/common/metrics/proto/permuted_entropy_cache.proto
diff --git a/chrome/common/metrics/proto/permuted_entropy_cache.proto b/chrome/common/metrics/proto/permuted_entropy_cache.proto
deleted file mode 100644
index 780712fb35c46044d6005ff94f6be3821c6bcb63..0000000000000000000000000000000000000000
--- a/chrome/common/metrics/proto/permuted_entropy_cache.proto
+++ /dev/null
@@ -1,19 +0,0 @@
-// Copyright 2013 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.
-
-syntax = "proto2";
-
-option optimize_for = LITE_RUNTIME;
-
-package metrics;
-
-// Represents a cache of permuted entropy mappings, where each entry maps from
-// a |randomization_seed| to a |value|.
-message PermutedEntropyCache {
-  message Entry {
-    required uint32 randomization_seed = 1;
-    required uint32 value = 2;
-  }
-  repeated Entry entry = 1;
-}