chromeos: Remove ash::SystemTrayDelegate::CreateTrayRotationLock

ash/system/tray/system_tray_delegate.cc

Index: ash/system/tray/system_tray_delegate.cc
diff --git a/ash/system/tray/system_tray_delegate.cc b/ash/system/tray/system_tray_delegate.cc
index e8f58c74b9b33c10352afbe3570d99a51468d7ac..f25ec4f3436d89296bc393fee477754c9fda52b9 100644
--- a/ash/system/tray/system_tray_delegate.cc
+++ b/ash/system/tray/system_tray_delegate.cc
@@ -5,13 +5,12 @@
 #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() {}
 
@@ -52,9 +51,4 @@ bool SystemTrayDelegate::IsSearchKeyMappedToCapsLock() {
   return false;
 }
 
-std::unique_ptr<SystemTrayItem> SystemTrayDelegate::CreateRotationLockTrayItem(
-    SystemTray* tray) {
-  return nullptr;
-}
-
 }  // namespace ash