LevelDBDatabase::Compact compacts db (on disk) w/o requiring reopen.

content/browser/indexed_db/leveldb/leveldb_database.cc

 // Copyright (c) 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 "content/browser/indexed_db/leveldb/leveldb_database.h"
 
 #include <cerrno>
 
 #include "base/basictypes.h"
 #include "base/files/file.h"
@@ skipping 377 matching lines @@
 }
 
 const LevelDBComparator* LevelDBDatabase::Comparator() const {
   return comparator_;
 }
 
 void LevelDBDatabase::Compact(const base::StringPiece& start,
                               const base::StringPiece& stop) {
   const leveldb::Slice start_slice = MakeSlice(start);
   const leveldb::Slice stop_slice = MakeSlice(stop);
+  // NULL batch means just wait for earlier writes to be done
+  db_->Write(leveldb::WriteOptions(), NULL);
   db_->CompactRange(&start_slice, &stop_slice);
 }
 
 void LevelDBDatabase::CompactAll() { db_->CompactRange(NULL, NULL); }
 
 }  // namespace content