cros: Remove supervised user methods from SystemTrayDelegate

ash/test/test_system_tray_delegate.h

 // Copyright 2013 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_TEST_TEST_SYSTEM_TRAY_DELEGATE_H_
 #define ASH_TEST_TEST_SYSTEM_TRAY_DELEGATE_H_
 
 #include "ash/system/tray/ime_info.h"
 #include "ash/system/tray/system_tray_delegate.h"
 #include "base/macros.h"
@@ skipping 15 matching lines @@
   void ClearSessionLengthLimit();
 
   // Sets the IME info.
   void SetCurrentIME(const IMEInfo& info);
 
   // Sets the list of available IMEs.
   void SetAvailableIMEList(const IMEInfoList& list);
 
   // SystemTrayDelegate:
   LoginStatus GetUserLoginStatus() const override;
-  std::string GetSupervisedUserManager() const override;
   bool GetSessionStartTime(base::TimeTicks* session_start_time) override;
   bool GetSessionLengthLimit(base::TimeDelta* session_length_limit) override;
   void GetCurrentIME(IMEInfo* info) override;
   void GetAvailableIMEList(IMEInfoList* list) override;
 
  private:
   base::TimeDelta session_length_limit_;
   bool session_length_limit_set_ = false;
   IMEInfo current_ime_;
   IMEInfoList ime_list_;
 
   DISALLOW_COPY_AND_ASSIGN(TestSystemTrayDelegate);
 };
 
 }  // namespace test
 }  // namespace ash
 
 #endif  // ASH_TEST_TEST_SYSTEM_TRAY_DELEGATE_H_