[Sync] Convert sync to a static library.

components/sync/core/read_transaction.h

 // Copyright 2012 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_CORE_READ_TRANSACTION_H_
 #define COMPONENTS_SYNC_CORE_READ_TRANSACTION_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "components/sync/api/attachments/attachment_id.h"
-#include "components/sync/base/sync_export.h"
 #include "components/sync/core/base_transaction.h"
 
 namespace tracked_objects {
 class Location;
 }  // namespace tracked_objects
 
 namespace sync_pb {
 class DataTypeContext;
 }
 
 namespace syncer {
 
 struct UserShare;
 
 // Sync API's ReadTransaction is a read-only BaseTransaction.  It wraps
 // a syncable::ReadTransaction.
-class SYNC_EXPORT ReadTransaction : public BaseTransaction {
+class ReadTransaction : public BaseTransaction {
  public:
   // Start a new read-only transaction on the specified repository.
   ReadTransaction(const tracked_objects::Location& from_here, UserShare* share);
 
   // Resume the middle of a transaction. Will not close transaction.
   ReadTransaction(UserShare* share, syncable::BaseTransaction* trans);
 
   ~ReadTransaction() override;
 
   // BaseTransaction override.
@@ skipping 20 matching lines @@
   // The underlying syncable object which this class wraps.
   syncable::BaseTransaction* transaction_;
   bool close_transaction_;
 
   DISALLOW_COPY_AND_ASSIGN(ReadTransaction);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_CORE_READ_TRANSACTION_H_