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

content/browser/BUILD.gn

 # 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.
 
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//media/media_options.gni")
 import("//ppapi/features/features.gni")
 import("//printing/features/features.gni")
 import("//third_party/WebKit/public/public_features.gni")
@@ skipping 758 matching lines @@
     "indexed_db/indexed_db_transaction_coordinator.cc",
     "indexed_db/indexed_db_transaction_coordinator.h",
     "indexed_db/indexed_db_value.cc",
     "indexed_db/indexed_db_value.h",
     "indexed_db/leveldb/leveldb_comparator.h",
     "indexed_db/leveldb/leveldb_database.cc",
     "indexed_db/leveldb/leveldb_database.h",
     "indexed_db/leveldb/leveldb_env.cc",
     "indexed_db/leveldb/leveldb_env.h",
     "indexed_db/leveldb/leveldb_factory.h",
+    "indexed_db/leveldb/leveldb_iterator.cc",
     "indexed_db/leveldb/leveldb_iterator.h",
     "indexed_db/leveldb/leveldb_iterator_impl.cc",
     "indexed_db/leveldb/leveldb_iterator_impl.h",
+    "indexed_db/leveldb/leveldb_iterator_pool_controller.h",
     "indexed_db/leveldb/leveldb_transaction.cc",
     "indexed_db/leveldb/leveldb_transaction.h",
     "indexed_db/leveldb/leveldb_write_batch.cc",
     "indexed_db/leveldb/leveldb_write_batch.h",
     "leveldb_wrapper_impl.cc",
     "leveldb_wrapper_impl.h",
     "loader/async_resource_handler.cc",
     "loader/async_resource_handler.h",
     "loader/async_revalidation_driver.cc",
     "loader/async_revalidation_driver.h",
@@ skipping 1242 matching lines @@
   if (!is_component_build) {
     public_deps = [
       ":browser",
     ]
   } else {
     public_deps = [
       "//third_party/leveldatabase",
     ]
   }
 }