[Sync] Convert sync to a static library.

components/sync/syncable/in_memory_directory_backing_store.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_SYNCABLE_IN_MEMORY_DIRECTORY_BACKING_STORE_H_
 #define COMPONENTS_SYNC_SYNCABLE_IN_MEMORY_DIRECTORY_BACKING_STORE_H_
 
 #include <string>
 
 #include "base/macros.h"
-#include "components/sync/base/sync_export.h"
 #include "components/sync/syncable/directory_backing_store.h"
 
 namespace syncer {
 namespace syncable {
 
 // This implementation of DirectoryBackingStore is used in tests that do not
 // require us to write to a file.  An in-memory sqlite database is much faster
 // than an on-disk database, so this can result in significant speedups in our
 // unit tests.
 //
 // An InMemoryDirectoryBackingStore cannot load data from existing databases.
 // When an InMemoryDirectoryBackingStore is destroyed, all data stored in this
 // database is lost.  If these limitations are a problem for you, consider using
 // TestDirectoryBackingStore.
-class SYNC_EXPORT InMemoryDirectoryBackingStore : public DirectoryBackingStore {
+class InMemoryDirectoryBackingStore : public DirectoryBackingStore {
  public:
   explicit InMemoryDirectoryBackingStore(const std::string& dir_name);
   DirOpenResult Load(Directory::MetahandlesMap* handles_map,
                      JournalIndex* delete_journals,
                      MetahandleSet* metahandles_to_purge,
                      Directory::KernelLoadInfo* kernel_load_info) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(InMemoryDirectoryBackingStore);
 };
 
 }  // namespace syncable
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_SYNCABLE_IN_MEMORY_DIRECTORY_BACKING_STORE_H_