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

ash/common/system/date/tray_system_info.h

 // Copyright 2016 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_SYSTEM_INFO_H_
 #define ASH_COMMON_SYSTEM_DATE_TRAY_SYSTEM_INFO_H_
 
-#if defined(OS_CHROMEOS)
 #include <memory>
-#endif  // defined(OS_CHROMEOS)
 
 #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 views {
 class Label;
 }
 
 namespace ash {
+class SystemClockObserver;
 class SystemInfoDefaultView;
-#if defined(OS_CHROMEOS)
-class SystemClockObserver;
-#endif
 
 namespace tray {
 class TimeView;
 }
 
 // The bottom row of the system menu. The default view shows the current date
 // and power status. The tray view shows the current time.
 class ASH_EXPORT TraySystemInfo : public SystemTrayItem, public ClockObserver {
  public:
   explicit TraySystemInfo(SystemTray* system_tray);
@@ skipping 17 matching lines @@
   void OnSystemClockCanSetTimeChanged(bool can_set_time) override;
   void Refresh() override;
 
   void SetupLabelForTimeTray(views::Label* label);
   void UpdateTimeFormat();
 
   tray::TimeView* tray_view_;
   SystemInfoDefaultView* default_view_;
   LoginStatus login_status_;
 
-#if defined(OS_CHROMEOS)
   std::unique_ptr<SystemClockObserver> system_clock_observer_;
-#endif
 
   DISALLOW_COPY_AND_ASSIGN(TraySystemInfo);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_DATE_TRAY_SYSTEM_INFO_H_