Add granular file tracing.

base/base.gypi

 # Copyright (c) 2012 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.
 
 {
   'includes': [
     'trace_event/trace_event.gypi',
   ],
   'target_defaults': {
     'variables': {
@@ skipping 191 matching lines @@
           'files/file_path_watcher_fsevents.h',
           'files/file_path_watcher_kqueue.cc',
           'files/file_path_watcher_kqueue.h',
           'files/file_path_watcher_linux.cc',
           'files/file_path_watcher_mac.cc',
           'files/file_path_watcher_stub.cc',
           'files/file_path_watcher_win.cc',
           'files/file_posix.cc',
           'files/file_proxy.cc',
           'files/file_proxy.h',
+          'files/file_tracing.cc',
+          'files/file_tracing.h',
           'files/file_util.cc',
           'files/file_util.h',
           'files/file_util_android.cc',
           'files/file_util_linux.cc',
           'files/file_util_mac.mm',
           'files/file_util_posix.cc',
           'files/file_util_proxy.cc',
           'files/file_util_proxy.h',
           'files/file_util_win.cc',
           'files/file_win.cc',
@@ skipping 798 matching lines @@
           'i18n/time_formatting.h',
           'i18n/timezone.cc',
           'i18n/timezone.h',
           'i18n/utf8_validator_tables.cc',
           'i18n/utf8_validator_tables.h',
         ],
       }]
     ],
   },
 }