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

ui/file_manager/audio_player/js/compiled_resources.gyp

Index: ui/file_manager/audio_player/js/compiled_resources.gyp
diff --git a/ui/file_manager/audio_player/js/compiled_resources.gyp b/ui/file_manager/audio_player/js/compiled_resources.gyp
index ab70260267e4b4fa2cfb67119a1cb20b71a29e27..d5d506edc8ebec6a4ec607d3de8df2414e563359 100644
--- a/ui/file_manager/audio_player/js/compiled_resources.gyp
+++ b/ui/file_manager/audio_player/js/compiled_resources.gyp
@@ -24,8 +24,13 @@
           '../../file_manager/common/js/volume_manager_common.js',
           '../../file_manager/background/js/app_window_wrapper.js',
           '../../file_manager/background/js/background_base.js',
+          '../../file_manager/background/js/entry_location_impl.js',
+          '../../file_manager/background/js/volume_info_impl.js',
+          '../../file_manager/background/js/volume_info_list_impl.js',
+          '../../file_manager/background/js/volume_manager_factory.js',
+          '../../file_manager/background/js/volume_manager_impl.js',
+          '../../file_manager/background/js/volume_manager_util.js',
           '../../file_manager/background/js/test_util_base.js',
-          '../../file_manager/background/js/volume_manager.js',
           'error_util.js',
           'test_util.js',
         ],
@@ -36,9 +41,12 @@
           '<(EXTERNS_DIR)/metrics_private.js',
           '../../../../third_party/analytics/externs.js',
           '../../externs/chrome_test.js',
+          '../../externs/entry_location.js',
           '../../externs/es6_workaround.js',
           '../../externs/platform.js',
           '../../externs/volume_info.js',
+          '../../externs/volume_info_list.js',
+          '../../externs/volume_manager.js',
         ],
       },
       'includes': [
@@ -86,7 +94,6 @@
           '../../file_manager/foreground/js/metadata/metadata_provider.js',
           '../../file_manager/foreground/js/metadata/multi_metadata_provider.js',
           '../../file_manager/foreground/js/metadata/thumbnail_model.js',
-          '../../file_manager/background/js/volume_manager.js',
           '../../file_manager/foreground/js/volume_manager_wrapper.js',
           '../elements/control_panel.js',
           '../elements/track_info_panel.js',
@@ -100,10 +107,14 @@
           '<(EXTERNS_DIR)/metrics_private.js',
           '../../../../third_party/analytics/externs.js',
           '../../externs/audio_player_foreground.js',
+          '../../externs/background_window_common.js',
           '../../externs/chrome_test.js',
+          '../../externs/entry_location.js',
           '../../externs/es6_workaround.js',
           '../../externs/platform.js',
           '../../externs/volume_info.js',
+          '../../externs/volume_info_list.js',
+          '../../externs/volume_manager.js',
         ],
       },
       'includes': [