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

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 ffa7463a0f39d9e7d5dbc46f651c027f7a9fb3b1..57df3cf1a3f657de04838e5f9f2f638a118724fd 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
@@ -10,13 +10,16 @@
   <script src="../../../../../ui/webui/resources/js/cr/event_target.js"></script>
   <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="../../background/js/volume_manager.js"></script>
+  <script src="../../background/js/entry_location_impl.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>
-
+  <script src="../../background/js/volume_info_impl.js"></script>
+  <script src="../../background/js/volume_info_list_impl.js"></script>
+  <script src="../../background/js/volume_manager_factory.js"></script>
+  <script src="../../background/js/volume_manager_impl.js"></script>
+  <script src="../../background/js/volume_manager_util.js"></script>
   <script src="unittest_util.js"></script>
   <script src="test_importer_common.js"></script>
   <script src="mock_entry.js"></script>