[Sync] Move sessions/ to engine/cycle/ and rename things to match.

components/sync/sessions/status_counters.h

-// 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.
-
-#ifndef COMPONENTS_SYNC_SESSIONS_STATUS_COUNTERS_H_
-#define COMPONENTS_SYNC_SESSIONS_STATUS_COUNTERS_H_
-
-#include <stddef.h>
-
-#include <memory>
-#include <string>
-
-#include "base/values.h"
-
-namespace syncer {
-
-// A class to maintain counts related to the current status of a sync type.
-struct StatusCounters {
-  StatusCounters();
-  ~StatusCounters();
-
-  std::unique_ptr<base::DictionaryValue> ToValue() const;
-  std::string ToString() const;
-
-  size_t num_entries;
-  size_t num_entries_and_tombstones;
-};
-
-}  // namespace syncer
-
-#endif  // COMPONENTS_SYNC_SESSIONS_STATUS_COUNTERS_H_