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

chrome/browser/sync_file_system/local/local_file_change_tracker.cc

 // Copyright 2013 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.
 
 #include "chrome/browser/sync_file_system/local/local_file_change_tracker.h"
 
 #include <stddef.h>
 #include <queue>
 #include <utility>
 
@@ skipping 475 matching lines @@
 
   std::string path =
       storage::FilePathToString(base_path_.Append(kDatabaseName));
   leveldb::Options options;
   options.max_open_files = 0;  // Use minimum.
   options.create_if_missing = true;
   options.reuse_logs = leveldb_env::kDefaultLogReuseOptionValue;
   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);
   if (status.ok()) {
     db_.reset(db);
     return SYNC_STATUS_OK;
   }
 
   HandleError(FROM_HERE, status);
   if (!status.IsCorruption())
@@ skipping 117 matching lines @@
   if (!status.ok() && !status.IsNotFound()) {
     HandleError(FROM_HERE, status);
     db_status_ = LevelDBStatusToSyncStatusCode(status);
     db_.reset();
     return db_status_;
   }
   return SYNC_STATUS_OK;
 }
 
 }  // namespace sync_file_system