[SyncFS] Wire up MetadataDatabaseIndex to MetadataDatabase

chrome/browser/sync_file_system/drive_backend/drive_backend_util.h

Index: chrome/browser/sync_file_system/drive_backend/drive_backend_util.h
diff --git a/chrome/browser/sync_file_system/drive_backend/drive_backend_util.h b/chrome/browser/sync_file_system/drive_backend/drive_backend_util.h
index ba9b851672d3913a20ea5b6b91d54d8b08973124..0d5f2bdaed9798ff0f1dd1d3c4f67687900cc186 100644
--- a/chrome/browser/sync_file_system/drive_backend/drive_backend_util.h
+++ b/chrome/browser/sync_file_system/drive_backend/drive_backend_util.h
@@ -68,6 +68,13 @@ scoped_ptr<google_apis::ResourceEntry> GetOldestCreatedFolderResource(
 SyncStatusCode GDataErrorCodeToSyncStatusCode(
     google_apis::GDataErrorCode error);
 
+template <typename T>
+scoped_ptr<T> Clone(const T* obj) {
+  if (!obj)
+    return scoped_ptr<T>();
+  return scoped_ptr<T>(new T(*obj));
+}
+
 template <typename Src, typename Dest>
 void AppendContents(const Src& src, Dest* dest) {
   dest->insert(dest->end(), src.begin(), src.end());