Add background-wide file metadata cache.

ui/file_manager/file_manager/background/js/duplicate_finder_unittest.html

Index: ui/file_manager/file_manager/background/js/duplicate_finder_unittest.html
diff --git a/ui/file_manager/file_manager/background/js/duplicate_finder_unittest.html b/ui/file_manager/file_manager/background/js/duplicate_finder_unittest.html
index 19e7befb5e4443a053a2e047a0b38b34b390fbee..dce0ddb2989f89ba1d02ff0bb7e29116d3aa7ebc 100644
--- a/ui/file_manager/file_manager/background/js/duplicate_finder_unittest.html
+++ b/ui/file_manager/file_manager/background/js/duplicate_finder_unittest.html
@@ -22,9 +22,11 @@
   <script src="../../common/js/importer_common.js"></script>
   <script src="../../common/js/progress_center_common.js"></script>
 
+  <script src="metadata_proxy.js"></script>
   <script src="entry_location_impl.js"></script>
   <script src="test_import_history.js"></script>
   <script src="mock_volume_manager.js"></script>
+  <script src="import_history.js"></script>
   <script src="duplicate_finder.js"></script>
   <script src="volume_info_impl.js"></script>
   <script src="volume_info_list_impl.js"></script>