Remove base::NonThreadSafe now that all users are gone!!

PRESUBMIT.py

 # 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.
 
 """Top-level presubmit script for Chromium.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into depot_tools.
 """
 
@@ skipping 313 matching lines @@
       'BrowserThread::GetBlockingPool',
       (
         'Use base/task_scheduler/post_task.h instead of the blocking pool. See',
         'mapping between both APIs in content/public/browser/browser_thread.h.',
         'For questions, contact base/task_scheduler/OWNERS.',
       ),
       True,
       (),
     ),
     (
-      'base::NonThreadSafe',
-      (
-        'base::NonThreadSafe is deprecated.',
-      ),
-      True,
-      (),
-    ),
-    (
       'base::SequenceChecker',
       (
         'Consider using SEQUENCE_CHECKER macros instead of the class directly.',
       ),
       False,
       (),
     ),
     (
       'base::ThreadChecker',
       (
@@ skipping 2162 matching lines @@
       output_api,
       json_url='http://chromium-status.appspot.com/current?format=json'))
 
   results.extend(
       input_api.canned_checks.CheckPatchFormatted(input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeHasBugField(
       input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeHasDescription(
       input_api, output_api))
   return results