Revert of Remove some pre-md code and assets.

ash/common/system/chromeos/settings/tray_settings.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_CHROMEOS_SETTINGS_TRAY_SETTINGS_H_
+#define ASH_COMMON_SYSTEM_CHROMEOS_SETTINGS_TRAY_SETTINGS_H_
+
+#include "ash/common/system/tray/system_tray_item.h"
+#include "base/macros.h"
+
+namespace ash {
+namespace tray {
+class SettingsDefaultView;
+}
+
+// TODO(tdanderson): Remove this class once material design is enabled by
+// default. See crbug.com/614453.
+class TraySettings : public SystemTrayItem {
+ public:
+  explicit TraySettings(SystemTray* system_tray);
+  ~TraySettings() override;
+
+ private:
+  // Overridden from SystemTrayItem
+  views::View* CreateTrayView(LoginStatus status) override;
+  views::View* CreateDefaultView(LoginStatus status) override;
+  views::View* CreateDetailedView(LoginStatus status) override;
+  void DestroyTrayView() override;
+  void DestroyDefaultView() override;
+  void DestroyDetailedView() override;
+  void UpdateAfterLoginStatusChange(LoginStatus status) override;
+
+  tray::SettingsDefaultView* default_view_;
+
+  DISALLOW_COPY_AND_ASSIGN(TraySettings);
+};
+
+}  // namespace ash
+
+#endif  // ASH_COMMON_SYSTEM_CHROMEOS_SETTINGS_TRAY_SETTINGS_H_