exo: Run exo in mus+ash

chrome/browser/chrome_browser_main_extra_parts_exo.h

 // Copyright 2015 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_CHROME_BROWSER_MAIN_EXTRA_PARTS_EXO_H_
 #define CHROME_BROWSER_CHROME_BROWSER_MAIN_EXTRA_PARTS_EXO_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "chrome/browser/chrome_browser_main_extra_parts.h"
 
 namespace exo {
 class Display;
+class WMHelper;
 namespace wayland {
 class Server;
 }
 }
 
 namespace arc {
 class ArcNotificationSurfaceManager;
 }
 
 class ChromeBrowserMainExtraPartsExo : public ChromeBrowserMainExtraParts {
  public:
   ChromeBrowserMainExtraPartsExo();
   ~ChromeBrowserMainExtraPartsExo() override;
 
   // Overridden from ChromeBrowserMainExtraParts:
   void PreProfileInit() override;
   void PostMainMessageLoopRun() override;
 
  private:
   std::unique_ptr<arc::ArcNotificationSurfaceManager>
       arc_notification_surface_manager_;
+  std::unique_ptr<exo::WMHelper> wm_helper_;
   std::unique_ptr<exo::Display> display_;
   std::unique_ptr<exo::wayland::Server> wayland_server_;
   class WaylandWatcher;
   std::unique_ptr<WaylandWatcher> wayland_watcher_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeBrowserMainExtraPartsExo);
 };
 
 #endif  // CHROME_BROWSER_CHROME_BROWSER_MAIN_EXTRA_PARTS_EXO_H_