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

content/browser/indexed_db/indexed_db_class_factory.h

Index: content/browser/indexed_db/indexed_db_class_factory.h
diff --git a/content/browser/indexed_db/indexed_db_class_factory.h b/content/browser/indexed_db/indexed_db_class_factory.h
index 3c218f0a8343bad65df564fdb908eb43ee5dce85..682efc464ebbce98c890cfb8fff700149fe2a8b0 100644
--- a/content/browser/indexed_db/indexed_db_class_factory.h
+++ b/content/browser/indexed_db/indexed_db_class_factory.h
@@ -19,6 +19,7 @@
 
 namespace leveldb {
 class Iterator;
+class Snapshot;
 }  // namespace leveldb
 
 namespace content {
@@ -55,7 +56,9 @@ class CONTENT_EXPORT IndexedDBClassFactory {
       IndexedDBBackingStore::Transaction* backing_store_transaction);
 
   virtual std::unique_ptr<LevelDBIteratorImpl> CreateIteratorImpl(
-      std::unique_ptr<leveldb::Iterator> iterator);
+      std::unique_ptr<leveldb::Iterator> iterator,
+      LevelDBDatabase* db,
+      const leveldb::Snapshot* snapshot);
 
   virtual scoped_refptr<LevelDBTransaction> CreateLevelDBTransaction(
       LevelDBDatabase* db);