mash: Fix system tray clock 12/24 hour time setting

ash/mus/system_tray_delegate_mus.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_MUS_SYSTEM_TRAY_DELEGATE_MUS_H_
+#define ASH_MUS_SYSTEM_TRAY_DELEGATE_MUS_H_
+
+#include "ash/common/system/tray/default_system_tray_delegate.h"
+#include "ash/public/interfaces/system_tray.mojom.h"
+#include "base/i18n/time_formatting.h"
+#include "base/macros.h"
+
+namespace ash {
+
+// Handles the settings displayed in the system tray menu. For mus most settings
+// are obtained from chrome browser via mojo IPC. For the classic ash version
+// see SystemTrayDelegateChromeOS.
+//
+// TODO: Support all methods in SystemTrayDelegate. http://crbug.com/647412.
+class SystemTrayDelegateMus : public DefaultSystemTrayDelegate,
+                              public mojom::SystemTray {
+ public:
+  SystemTrayDelegateMus();
+  ~SystemTrayDelegateMus() override;
+
+  static SystemTrayDelegateMus* Get();
+
+ private:
+  // SystemTrayDelegate:
+  base::HourClockType GetHourClockType() const override;
+
+  // mojom::SystemTray:
+  void SetUse24HourClock(bool use_24_hour) override;
+
+  // 12 or 24 hour display.
+  base::HourClockType hour_clock_type_;
+
+  DISALLOW_COPY_AND_ASSIGN(SystemTrayDelegateMus);
+};
+
+}  // namespace ash
+
+#endif  // ASH_MUS_SYSTEM_TRAY_DELEGATE_MUS_H_