Thread::Stop() must be called before any subclass's destructor completes.

net/base/network_change_notifier_linux.cc

 // Copyright (c) 2011 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 "net/base/network_change_notifier_linux.h"
 
 #include <errno.h>
 #include <sys/socket.h>
 
 #include "base/bind.h"
@@ skipping 87 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(Thread);
 };
 
 NetworkChangeNotifierLinux::Thread::Thread()
     : base::Thread("NetworkChangeNotifier"),
       netlink_fd_(kInvalidSocket),
       ALLOW_THIS_IN_INITIALIZER_LIST(ptr_factory_(this)) {
 }
 
-NetworkChangeNotifierLinux::Thread::~Thread() {}
+NetworkChangeNotifierLinux::Thread::~Thread() {
+  DCHECK(!Thread::IsRunning());
+}
 
 void NetworkChangeNotifierLinux::Thread::Init() {
   resolv_file_watcher_.reset(new FilePathWatcher);
   hosts_file_watcher_.reset(new FilePathWatcher);
   file_watcher_delegate_ = new DNSWatchDelegate(base::Bind(
       &NetworkChangeNotifierLinux::Thread::NotifyObserversOfDNSChange,
       base::Unretained(this)));
   if (!resolv_file_watcher_->Watch(
           FilePath(FILE_PATH_LITERAL("/etc/resolv.conf")),
           file_watcher_delegate_.get())) {
@@ skipping 88 matching lines @@
 NetworkChangeNotifierLinux::NetworkChangeNotifierLinux()
     : notifier_thread_(new Thread) {
   // We create this notifier thread because the notification implementation
   // needs a MessageLoopForIO, and there's no guarantee that
   // MessageLoop::current() meets that criterion.
   base::Thread::Options thread_options(MessageLoop::TYPE_IO, 0);
   notifier_thread_->StartWithOptions(thread_options);
 }
 
 NetworkChangeNotifierLinux::~NetworkChangeNotifierLinux() {
-  // We don't need to explicitly Stop(), but doing so allows us to sanity-
-  // check that the notifier thread shut down properly.
+  // Stopping from here allows us to sanity- check that the notifier
+  // thread shut down properly.
   notifier_thread_->Stop();
 }
 
 bool NetworkChangeNotifierLinux::IsCurrentlyOffline() const {
   // TODO(eroman): http://crbug.com/53473
   return false;
 }
 
 }  // namespace net