[Sync] Convert sync to a static library.

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"
-#include "components/sync/base/sync_export.h"
 
 namespace syncer {
 
 // A class to maintain counts related to sync commit requests and responses.
-struct SYNC_EXPORT CommitCounters {
+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_