chromeos: Fix shelf appearing at login screen under mash

chrome/browser/ui/views/ash/chrome_browser_main_extra_parts_ash.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_VIEWS_ASH_CHROME_BROWSER_MAIN_EXTRA_PARTS_ASH_H_
 #define CHROME_BROWSER_UI_VIEWS_ASH_CHROME_BROWSER_MAIN_EXTRA_PARTS_ASH_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "chrome/browser/chrome_browser_main_extra_parts.h"
 
 class CastConfigClientMediaRouter;
 class ChromeBrowserMainExtraPartsViews;
 class ChromeLauncherControllerMus;
 class ChromeNewWindowClient;
 class ImmersiveContextMus;
 class ImmersiveHandlerFactoryMus;
 class MediaClient;
 class SessionControllerClient;
 class SystemTrayClient;
 class VolumeController;
 class VpnListForwarder;
 
+// Browser initialization for Ash. Only runs on Chrome OS.
+// TODO(jamescook): Fold this into ChromeBrowserMainPartsChromeOS.
 class ChromeBrowserMainExtraPartsAsh : public ChromeBrowserMainExtraParts {
  public:
   explicit ChromeBrowserMainExtraPartsAsh(
       ChromeBrowserMainExtraPartsViews* extra_parts_views);
   ~ChromeBrowserMainExtraPartsAsh() override;
 
   // Overridden from ChromeBrowserMainExtraParts:
   void PreProfileInit() override;
   void PostProfileInit() override;
   void PostMainMessageLoopRun() override;
 
  private:
   ChromeBrowserMainExtraPartsViews* extra_parts_views_;
 
   std::unique_ptr<ChromeLauncherControllerMus> chrome_launcher_controller_mus_;
   std::unique_ptr<CastConfigClientMediaRouter> cast_config_client_media_router_;
   std::unique_ptr<MediaClient> media_client_;
   std::unique_ptr<ImmersiveHandlerFactoryMus> immersive_handler_factory_;
   std::unique_ptr<ImmersiveContextMus> immersive_context_;
   std::unique_ptr<SessionControllerClient> session_controller_client_;
   std::unique_ptr<SystemTrayClient> system_tray_client_;
   std::unique_ptr<ChromeNewWindowClient> new_window_client_;
   std::unique_ptr<VolumeController> volume_controller_;
   std::unique_ptr<VpnListForwarder> vpn_list_forwarder_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeBrowserMainExtraPartsAsh);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_ASH_CHROME_BROWSER_MAIN_EXTRA_PARTS_ASH_H_