Revert of chromeos: Remove SystemTrayDelegate::GetIMEManagedMessage()

ash/system/tray/system_tray_delegate.h

Index: ash/system/tray/system_tray_delegate.h
diff --git a/ash/system/tray/system_tray_delegate.h b/ash/system/tray/system_tray_delegate.h
index 45d701d097410da87d4e7493cf322347f6facfe6..c0e26deb1215c06be33633d78a3545e84719f846 100644
--- a/ash/system/tray/system_tray_delegate.h
+++ b/ash/system/tray/system_tray_delegate.h
@@ -53,6 +53,9 @@
   // Returns a list of properties for the currently selected IME.
   virtual void GetCurrentIMEProperties(IMEPropertyInfoList* list);
 
+  // Returns a non-empty string if IMEs are managed by policy.
+  virtual base::string16 GetIMEManagedMessage();
+
   // Returns NetworkingConfigDelegate. May return nullptr.
   virtual NetworkingConfigDelegate* GetNetworkingConfigDelegate() const;