Add background-wide file metadata cache.

ui/file_manager/file_manager/common/js/importer_common_unittest.html

Index: ui/file_manager/file_manager/common/js/importer_common_unittest.html
diff --git a/ui/file_manager/file_manager/common/js/importer_common_unittest.html b/ui/file_manager/file_manager/common/js/importer_common_unittest.html
index 57df3cf1a3f657de04838e5f9f2f638a118724fd..0e8361879ea1920433958b96780c2dfe465a8578 100644
--- a/ui/file_manager/file_manager/common/js/importer_common_unittest.html
+++ b/ui/file_manager/file_manager/common/js/importer_common_unittest.html
@@ -11,7 +11,9 @@
   <script src="../../../../../ui/webui/resources/js/cr/ui/array_data_model.js"></script>
   <script src="../../../../../ui/webui/resources/js/load_time_data.js"></script>
   <script src="volume_manager_common.js"></script>
+  <script src="../../common/js/lru_cache.js"></script>
   <script src="../../background/js/entry_location_impl.js"></script>
+  <script src="../../background/js/metadata_proxy.js"></script>
   <script src="../../background/js/mock_file_operation_manager.js"></script>
   <script src="../../background/js/mock_volume_manager.js"></script>
   <script src="../../background/js/mock_media_scanner.js"></script>