nsresult ConstructContractID(nsString& aContractID, const nsString& aMimeType)
nsresult ConstructContractID(nsCString& aContractID, const nsString& aMimeType)
nsresult ConstructContractID(nsString& aContractID, const nsString& aMimeType){  aContractID.AssignWithConversion(kTransformerContractIDPrefix);  aContractID.Append(aMimeType);  return NS_OK;}