[Sync] Convert sync to a static library.

components/sync/api/metadata_batch.h

 // Copyright 2015 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_API_METADATA_BATCH_H_
 #define COMPONENTS_SYNC_API_METADATA_BATCH_H_
 
 #include <map>
 #include <string>
 
-#include "components/sync/base/sync_export.h"
 #include "components/sync/protocol/data_type_state.pb.h"
 #include "components/sync/protocol/entity_metadata.pb.h"
 
 namespace syncer_v2 {
 
 // Map of client tag to EntityMetadata proto.
 typedef std::map<std::string, sync_pb::EntityMetadata> EntityMetadataMap;
 
 // Container used to pass sync metadata from services to their processor.
-class SYNC_EXPORT MetadataBatch {
+class MetadataBatch {
  public:
   MetadataBatch();
   virtual ~MetadataBatch();
 
   // Allows the caller to take ownership of the entire metadata map. This is
   // done because the caller will probably swap out all the EntityMetadata
   // protos from the map for performance reasons.
   EntityMetadataMap&& TakeAllMetadata();
 
   // Add |metadata| for |client_tag| to the batch.
   void AddMetadata(const std::string& client_tag,
                    const sync_pb::EntityMetadata& metadata);
 
   // Get the DataTypeState for this batch.
   const sync_pb::DataTypeState& GetDataTypeState() const;
 
   // Set the DataTypeState for this batch.
   void SetDataTypeState(const sync_pb::DataTypeState& state);
 
  private:
   EntityMetadataMap metadata_map_;
   sync_pb::DataTypeState state_;
 };
 
 }  // namespace syncer_v2
 
 #endif  // COMPONENTS_SYNC_API_METADATA_BATCH_H_