linux: add UMA stat for the file system where the prefs are stored

base/base.gypi

 # Copyright (c) 2010 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.
 
 {
   'target_defaults': {
     'variables': {
       'base_target': 0,
       'base_extra_target': 0,
     },
@@ skipping 59 matching lines @@
           'event_trace_controller_win.h',
           'event_trace_provider_win.cc',
           'event_trace_provider_win.h',
           'event_synthesis_gtk.cc',
           'event_synthesis_gtk.h',
           'file_path.cc',
           'file_path.h',
           'file_util.cc',
           'file_util.h',
           'file_util_deprecated.h',
+          'file_util_linux.cc',
           'file_util_mac.mm',
           'file_util_posix.cc',
           'file_util_win.cc',
           'file_version_info.h',
           'file_version_info_mac.h',
           'file_version_info_mac.mm',
           'file_version_info_win.cc',
           'file_version_info_win.h',
           'fix_wp64.h',
           'float_util.h',
@@ skipping 662 matching lines @@
             'third_party/xdg_mime/xdgmimemagic.c',
             'third_party/xdg_mime/xdgmimemagic.h',
             'third_party/xdg_mime/xdgmimeparent.c',
             'third_party/xdg_mime/xdgmimeparent.h',
           ],
         },
       ],
     }],
   ],
 }