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

components/sync/sessions/commit_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_COMMIT_COUNTERS_H_
-#define COMPONENTS_SYNC_SESSIONS_COMMIT_COUNTERS_H_
-
-#include <memory>
-#include <string>
-
-#include "base/values.h"
-
-namespace syncer {
-
-// A class to maintain counts related to sync commit requests and responses.
-struct CommitCounters {
-  CommitCounters();
-  ~CommitCounters();
-
-  std::unique_ptr<base::DictionaryValue> ToValue() const;
-  std::string ToString() const;
-
-  int num_commits_attempted;
-  int num_commits_success;
-  int num_commits_conflict;
-  int num_commits_error;
-};
-
-}  // namespace syncer
-
-#endif  // COMPONENTS_SYNC_SESSIONS_COMMIT_COUNTERS_H_