[IndexedDB] Pool and evict leveldb iterators, to save memory

content/browser/indexed_db/indexed_db_class_factory.cc

 // Copyright 2014 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/indexed_db_class_factory.h"
 
 #include <utility>
 
 #include "base/memory/ptr_util.h"
 #include "content/browser/indexed_db/indexed_db_factory.h"
@@ skipping 36 matching lines @@
   return std::unique_ptr<IndexedDBTransaction>(new IndexedDBTransaction(
       id, connection, scope, mode, backing_store_transaction));
 }
 
 scoped_refptr<LevelDBTransaction>
 IndexedDBClassFactory::CreateLevelDBTransaction(LevelDBDatabase* db) {
   return new LevelDBTransaction(db);
 }
 
 std::unique_ptr<LevelDBIteratorImpl> IndexedDBClassFactory::CreateIteratorImpl(
-    std::unique_ptr<leveldb::Iterator> iterator) {
-  return base::WrapUnique(new LevelDBIteratorImpl(std::move(iterator)));
+    std::unique_ptr<leveldb::Iterator> iterator,
+    LevelDBDatabase* db,
+    const leveldb::Snapshot* snapshot) {
+  return base::WrapUnique(
+      new LevelDBIteratorImpl(std::move(iterator), db, snapshot));
 }
 
 }  // namespace content