Remove non-cros support from ash/common/system.

ash/common/system/date/tray_date.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 ASH_COMMON_SYSTEM_DATE_TRAY_DATE_H_
 #define ASH_COMMON_SYSTEM_DATE_TRAY_DATE_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
 #include "ash/common/login_status.h"
 #include "ash/common/system/date/clock_observer.h"
 #include "ash/common/system/tray/system_tray_item.h"
 #include "base/macros.h"
 
 namespace ash {
 class DateDefaultView;
-#if defined(OS_CHROMEOS)
 class SystemClockObserver;
-#endif
 
 namespace tray {
 class TimeView;
 }
 
 // System tray item for the time and date.
 class ASH_EXPORT TrayDate : public SystemTrayItem, public ClockObserver {
  public:
   enum ClockLayout {
     HORIZONTAL_CLOCK,
@@ skipping 30 matching lines @@
   // Overridden from ClockObserver.
   void OnDateFormatChanged() override;
   void OnSystemClockTimeUpdated() override;
   void OnSystemClockCanSetTimeChanged(bool can_set_time) override;
   void Refresh() override;
 
   tray::TimeView* time_tray_;
   DateDefaultView* default_view_;
   LoginStatus login_status_;
 
-#if defined(OS_CHROMEOS)
   std::unique_ptr<SystemClockObserver> system_clock_observer_;
-#endif
 
   DISALLOW_COPY_AND_ASSIGN(TrayDate);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_DATE_TRAY_DATE_H_