chromeos: Remove SystemTrayDelegate::GetIMEManagedMessage()

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 a825be27060f5e5b0bc2b265312fa80997a69ca1..5553ad05d02a2113bb7e08d0faa86fea00078f78 100644
--- a/ash/system/tray/system_tray_delegate.cc
+++ b/ash/system/tray/system_tray_delegate.cc
@@ -22,10 +22,6 @@ void SystemTrayDelegate::GetAvailableIMEList(IMEInfoList* list) {}
 
 void SystemTrayDelegate::GetCurrentIMEProperties(IMEPropertyInfoList* list) {}
 
-base::string16 SystemTrayDelegate::GetIMEManagedMessage() {
-  return base::string16();
-}
-
 NetworkingConfigDelegate* SystemTrayDelegate::GetNetworkingConfigDelegate()
     const {
   return nullptr;