Divide volume_manager.js into files for each classes and extract interfaces from them.

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 556529dfaf634f4557e287c0e5b0cc1096b35e77..19e7befb5e4443a053a2e047a0b38b34b390fbee 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
@@ -22,10 +22,15 @@
   <script src="../../common/js/importer_common.js"></script>
   <script src="../../common/js/progress_center_common.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="duplicate_finder.js"></script>
-  <script src="volume_manager.js"></script>
+  <script src="volume_info_impl.js"></script>
+  <script src="volume_info_list_impl.js"></script>
+  <script src="volume_manager_factory.js"></script>
+  <script src="volume_manager_impl.js"></script>
+  <script src="volume_manager_util.js"></script>
 
   <script src="duplicate_finder_unittest.js"></script>
 </body>