Remove OS_CHROMEOS from ui/ash code

chrome/browser/ui/ash/system_tray_delegate_common.h

-// Copyright 2014 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_ASH_SYSTEM_TRAY_DELEGATE_COMMON_H_
-#define CHROME_BROWSER_UI_ASH_SYSTEM_TRAY_DELEGATE_COMMON_H_
-
-#include <memory>
-#include <string>
-
-#include "ash/system/tray/system_tray_delegate.h"
-#include "base/compiler_specific.h"
-#include "base/i18n/time_formatting.h"
-#include "base/macros.h"
-#include "content/public/browser/notification_observer.h"
-#include "content/public/browser/notification_registrar.h"
-
-// Common base class for platform-specific implementations.
-class SystemTrayDelegateCommon : public ash::SystemTrayDelegate,
-                                 public content::NotificationObserver {
- public:
-  SystemTrayDelegateCommon();
-
-  ~SystemTrayDelegateCommon() override;
-
-  // Overridden from ash::SystemTrayDelegate:
-  void Initialize() override;
-  void Shutdown() override;
-  bool GetTrayVisibilityOnStartup() override;
-  ash::user::LoginStatus GetUserLoginStatus() const override;
-  bool IsUserSupervised() const override;
-  bool IsUserChild() const override;
-  void GetSystemUpdateInfo(ash::UpdateInfo* info) const override;
-  base::HourClockType GetHourClockType() const override;
-  void ShowChromeSlow() override;
-  void ShowHelp() override;
-  void RequestRestartForUpdate() override;
-  int GetSystemTrayMenuWidth() override;
-
- private:
-  void UpdateClockType();
-
-  // content::NotificationObserver implementation.
-  void Observe(int type,
-               const content::NotificationSource& source,
-               const content::NotificationDetails& details) override;
-
-  std::unique_ptr<content::NotificationRegistrar> registrar_;
-  base::HourClockType clock_type_;
-
-  DISALLOW_COPY_AND_ASSIGN(SystemTrayDelegateCommon);
-};
-
-#endif  // CHROME_BROWSER_UI_ASH_SYSTEM_TRAY_DELEGATE_COMMON_H_