[sync] Componentize sync: Part 6: Add more SYNC_EXPORTs to files in src/sync/

sync/syncable/invalid_directory_backing_store.h

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// 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 SYNC_SYNCABLE_INVALID_DIRECTORY_BACKING_STORE_H_
 #define SYNC_SYNCABLE_INVALID_DIRECTORY_BACKING_STORE_H_
 
 #include "sync/syncable/directory_backing_store.h"
+#include "sync/base/sync_export.h"
 
 namespace syncer {
 namespace syncable {
 
 // A class used to test scenarios where loading a directory fails.
-class InvalidDirectoryBackingStore : public DirectoryBackingStore {
+class SYNC_EXPORT_PRIVATE InvalidDirectoryBackingStore
+    : public DirectoryBackingStore {
  public:
   InvalidDirectoryBackingStore();
   virtual ~InvalidDirectoryBackingStore();
   virtual DirOpenResult Load(
       MetahandlesIndex* entry_bucket,
       Directory::KernelLoadInfo* kernel_load_info) OVERRIDE;
  private:
   DISALLOW_COPY_AND_ASSIGN(InvalidDirectoryBackingStore);
 };
 
 }  // namespace syncable
 }  // namespace syncer
 
 #endif  // SYNC_SYNCABLE_INVALID_DIRECTORY_BACKING_STORE_H_