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

chrome/browser/sync_file_system/local/local_file_change_tracker.cc

Index: chrome/browser/sync_file_system/local/local_file_change_tracker.cc
diff --git a/chrome/browser/sync_file_system/local/local_file_change_tracker.cc b/chrome/browser/sync_file_system/local/local_file_change_tracker.cc
index c1e6a7b4929b2e9710726df9ae5dd0f6f858d011..f566fbf9c418dbe49853390ebac154ef7470fc06 100644
--- a/chrome/browser/sync_file_system/local/local_file_change_tracker.cc
+++ b/chrome/browser/sync_file_system/local/local_file_change_tracker.cc
@@ -493,7 +493,7 @@ SyncStatusCode LocalFileChangeTracker::TrackerDB::Init(
   if (env_override_)
     options.env = env_override_;
   leveldb::DB* db;
-  leveldb::Status status = leveldb::DB::Open(options, path, &db);
+  leveldb::Status status = leveldb_env::DBRegistry::Open(options, path, &db);
   UMA_HISTOGRAM_ENUMERATION("SyncFileSystem.TrackerDB.Open",
                             leveldb_env::GetLevelDBStatusUMAValue(status),
                             leveldb_env::LEVELDB_STATUS_MAX);