Destroy NightLightController before PrefService

ash/shell.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 "ash/shell.h"
 
 #include <algorithm>
 #include <string>
 #include <utility>
 
@@ skipping 767 matching lines @@
 
   PowerStatus::Shutdown();
 
   // Ensure that DBusThreadManager outlives this Shell.
   DCHECK(chromeos::DBusThreadManager::IsInitialized());
 
   // Needs to happen right before |instance_| is reset.
   shell_port_.reset();
   session_controller_->RemoveObserver(this);
   wallpaper_delegate_.reset();
+  // NightLightController depeneds on the PrefService and must be destructed
+  // before it. crbug.com/724231.
+  night_light_controller_ = nullptr;
   pref_service_ = nullptr;
   shell_delegate_.reset();
 
   DCHECK(instance_ == this);
   instance_ = nullptr;
 }
 
 void Shell::Init(const ShellInitParams& init_params) {
   const Config config = shell_port_->GetAshConfig();
 
@@ skipping 477 matching lines @@
 void Shell::OnPrefServiceInitialized(
     std::unique_ptr<::PrefService> pref_service) {
   if (!instance_)
     return;
   // |pref_service_| is null if can't connect to Chrome (as happens when
   // running mash outside of chrome --mash and chrome isn't built).
   pref_service_ = std::move(pref_service);
 }
 
 }  // namespace ash