leveldb: Add DBTracker for exposing databases to Chrome's memory-infra.

chrome/browser/sync_file_system/drive_backend/metadata_database.cc

Index: chrome/browser/sync_file_system/drive_backend/metadata_database.cc
diff --git a/chrome/browser/sync_file_system/drive_backend/metadata_database.cc b/chrome/browser/sync_file_system/drive_backend/metadata_database.cc
index fd4de8c5ccff273e37f5f101f31c54ba8cf46e1e..432fb0fe13f77aa40ee0898f87e9131eb8bda292 100644
--- a/chrome/browser/sync_file_system/drive_backend/metadata_database.cc
+++ b/chrome/browser/sync_file_system/drive_backend/metadata_database.cc
@@ -224,7 +224,7 @@ SyncStatusCode OpenDatabase(const base::FilePath& path,
     options.env = env_override;
   leveldb::DB* db = nullptr;
   leveldb::Status db_status =
-      leveldb::DB::Open(options, path.AsUTF8Unsafe(), &db);
+      leveldb_env::DBRegistry::Open(options, path.AsUTF8Unsafe(), &db);
   UMA_HISTOGRAM_ENUMERATION("SyncFileSystem.Database.Open",
                             leveldb_env::GetLevelDBStatusUMAValue(db_status),
                             leveldb_env::LEVELDB_STATUS_MAX);