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

content/browser/indexed_db/indexed_db_cleanup_on_io_error_unittest.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 <cerrno>
 
 #include "base/files/file.h"
 #include "base/files/file_path.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/macros.h"
@@ skipping 24 matching lines @@
 }
 
 namespace content {
 class IndexedDBFactory;
 }
 
 namespace {
 
 class BustedLevelDBDatabase : public LevelDBDatabase {
  public:
-  BustedLevelDBDatabase() {}
+  BustedLevelDBDatabase()
+      : LevelDBDatabase(LevelDBDatabase::kDefaultMaxOpenIteratorsPerDatabase) {}
   static std::unique_ptr<LevelDBDatabase> Open(
       const base::FilePath& file_name,
       const LevelDBComparator* /*comparator*/) {
     return base::MakeUnique<BustedLevelDBDatabase>();
   }
   leveldb::Status Get(const base::StringPiece& key,
                       std::string* value,
                       bool* found,
                       const LevelDBSnapshot* = 0) override {
     return leveldb::Status::IOError("It's busted!");
@@ skipping 108 matching lines @@
                                           leveldb_env::kNewLogger,
                                           base::File::FILE_ERROR_FAILED));
   scoped_refptr<IndexedDBBackingStore> backing_store4 =
       IndexedDBBackingStore::Open(
           factory, origin, path, request_context_getter, &data_loss_info,
           &disk_full, &mock_leveldb_factory, task_runner, clean_journal, &s);
   ASSERT_TRUE(s.IsIOError());
 }
 
 }  // namespace