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

sync/syncable/on_disk_directory_backing_store.h

Index: sync/syncable/on_disk_directory_backing_store.h
diff --git a/sync/syncable/on_disk_directory_backing_store.h b/sync/syncable/on_disk_directory_backing_store.h
index 0bf720bf540a2eb85d05189734c74d828ff457f9..95a61e1e9a702c48d3f06189bc420f4f01451852 100644
--- a/sync/syncable/on_disk_directory_backing_store.h
+++ b/sync/syncable/on_disk_directory_backing_store.h
@@ -1,4 +1,4 @@
-// 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.
 
@@ -6,6 +6,7 @@
 #define SYNC_SYNCABLE_ON_DISK_DIRECTORY_BACKING_STORE_H_
 
 #include "base/file_path.h"
+#include "sync/base/sync_export.h"
 #include "sync/syncable/directory_backing_store.h"
 
 namespace syncer {
@@ -13,7 +14,8 @@ namespace syncable {
 
 // This is the concrete class that provides a useful implementation of
 // DirectoryBackingStore.
-class OnDiskDirectoryBackingStore : public DirectoryBackingStore {
+class SYNC_EXPORT_PRIVATE OnDiskDirectoryBackingStore
+    : public DirectoryBackingStore {
  public:
   OnDiskDirectoryBackingStore(const std::string& dir_name,
                               const FilePath& backing_filepath);
@@ -37,6 +39,8 @@ class OnDiskDirectoryBackingStore : public DirectoryBackingStore {
 
   bool allow_failure_for_test_;
   FilePath backing_filepath_;
+
+  DISALLOW_COPY_AND_ASSIGN(OnDiskDirectoryBackingStore);
 };
 
 }  // namespace syncable