Add UMA to count directory-changed events by RootType.

ui/file_manager/file_manager/foreground/js/compiled_resources2.gyp

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 {
   'targets': [
     {
       'target_name': 'actions_controller',
       'dependencies': [
         '<(DEPTH)/ui/webui/resources/js/compiled_resources2.gyp:assert',
         '<(DEPTH)/ui/webui/resources/js/compiled_resources2.gyp:cr',
@@ skipping 87 matching lines @@
         '../../common/js/compiled_resources2.gyp:importer_common',
         '../../common/js/compiled_resources2.gyp:metrics',
         'directory_contents',
         'file_watcher',
         'ui/compiled_resources2.gyp:file_list_selection_model',
         'volume_manager_wrapper',
       ],
       'includes': ['../../../compile_js2.gypi'],
     },
     {
+      'target_name': 'navigation_uma',
+      'dependencies': [
+        'dialog_type',
+        'volume_manager_wrapper',
+      ],
+      'includes': ['../../../compile_js2.gypi'],
+    },
+    {
       'target_name': 'directory_tree_naming_controller',
       'dependencies': [
         '../../common/js/compiled_resources2.gyp:util',
         '<(DEPTH)/ui/webui/resources/js/cr/ui/compiled_resources2.gyp:dialogs',
         'directory_model',
         'ui/compiled_resources2.gyp:directory_tree',
       ],
       'includes': ['../../../compile_js2.gypi'],
     },
     {
@@ skipping 414 matching lines @@
     {
       'target_name': 'webui_command_extender',
       'dependencies': [
         '<(DEPTH)/ui/webui/resources/js/compiled_resources2.gyp:cr',
         '<(DEPTH)/ui/webui/resources/js/cr/ui/compiled_resources2.gyp:command',
       ],
       'includes': ['../../../compile_js2.gypi'],
     },
  ],
 }