Remove some pre-md code and assets.

ash/common/system/chromeos/settings/tray_settings.h

Index: ash/common/system/chromeos/settings/tray_settings.h
diff --git a/ash/common/system/chromeos/settings/tray_settings.h b/ash/common/system/chromeos/settings/tray_settings.h
deleted file mode 100644
index 974856c3eb91642fb7c02c7727d849a33a218530..0000000000000000000000000000000000000000
--- a/ash/common/system/chromeos/settings/tray_settings.h
+++ /dev/null
@@ -1,40 +0,0 @@
-// 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_