Turn on verbose flag for compiling file_manager.

ui/file_manager/file_manager/background/js/compiled_resources.gyp

Index: ui/file_manager/file_manager/background/js/compiled_resources.gyp
diff --git a/ui/file_manager/file_manager/background/js/compiled_resources.gyp b/ui/file_manager/file_manager/background/js/compiled_resources.gyp
index 81a2702e47a581db3a96618069767397a02880bf..a0216b549cb69055ce35b07d251d045251749c4b 100644
--- a/ui/file_manager/file_manager/background/js/compiled_resources.gyp
+++ b/ui/file_manager/file_manager/background/js/compiled_resources.gyp
@@ -10,6 +10,7 @@
           '../../../../../third_party/jstemplate/compiled_resources.gyp:jstemplate',
           '../../../../webui/resources/js/load_time_data.js',
           '../../../../webui/resources/js/cr.js',
+          '../../../../webui/resources/js/cr/ui.js',
           '../../../../webui/resources/js/util.js',
           '../../../../webui/resources/js/cr/event_target.js',
           '../../../../webui/resources/js/cr/ui/array_data_model.js',
@@ -38,10 +39,10 @@
           'file_operation_util.js',
           'import_history.js',
           'launcher_search.js',
+          'task_queue.js',
           'media_import_handler.js',
           'media_scanner.js',
           'progress_center.js',
-          'task_queue.js',
           'volume_manager.js',
           'background_base.js',
         ],
@@ -61,6 +62,9 @@
           '../../../externs/platform.js',
           '../../common/js/externs.js',
         ],
+        'closure_args': [
+          'warning_level=VERBOSE'
+        ]
       },
       'includes': [
         '../../../../../third_party/closure_compiler/compile_js.gypi'