chromeos: Remove ash::SystemTrayDelegate::CreateTrayRotationLock

ash/system/tray/system_tray_delegate.cc

 // 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.
 
 #include "ash/system/tray/system_tray_delegate.h"
 
 #include "ash/system/tray/ime_info.h"
-#include "ash/system/tray/system_tray_item.h"
 
 namespace ash {
 
-SystemTrayDelegate::SystemTrayDelegate() {}
+SystemTrayDelegate::SystemTrayDelegate() = default;
 
-SystemTrayDelegate::~SystemTrayDelegate() {}
+SystemTrayDelegate::~SystemTrayDelegate() = default;
 
 void SystemTrayDelegate::Initialize() {}
 
 void SystemTrayDelegate::ShowUserLogin() {}
 
 void SystemTrayDelegate::GetCurrentIME(IMEInfo* info) {}
 
 void SystemTrayDelegate::GetAvailableIMEList(IMEInfoList* list) {}
 
 void SystemTrayDelegate::GetCurrentIMEProperties(IMEPropertyInfoList* list) {}
@@ skipping 20 matching lines @@
     base::TimeDelta* session_length_limit) {
   return false;
 }
 
 void SystemTrayDelegate::ActiveUserWasChanged() {}
 
 bool SystemTrayDelegate::IsSearchKeyMappedToCapsLock() {
   return false;
 }
 
-std::unique_ptr<SystemTrayItem> SystemTrayDelegate::CreateRotationLockTrayItem(
-    SystemTray* tray) {
-  return nullptr;
-}
-
 }  // namespace ash