Require FilePathWatcher destructor to be called in sequence with Watch().

base/files/file_path_watcher_linux.cc

 // 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.
 
 #include "base/files/file_path_watcher.h"
 
 #include <errno.h>
 #include <stddef.h>
 #include <string.h>
 #include <sys/inotify.h>
@@ skipping 639 matching lines @@
   for (size_t i = 0; i < watches_.size() - 1; ++i) {
     if (watches_[i].subdir.empty())
       return false;
   }
   return watches_.back().subdir.empty();
 }
 
 }  // namespace
 
 FilePathWatcher::FilePathWatcher() {
+  sequence_checker_.DetachFromSequence();
   impl_ = new FilePathWatcherImpl();
 }
 
 }  // namespace base