mMimeURLUtilsFactory = null_nsCOMPtr();
void nsMimeModule::Shutdown(){    // Release the factory object    mObjectClassAccessFactory = null_nsCOMPtr();    mMimeConverterFactory = null_nsCOMPtr();    mStreamConverterFactory = null_nsCOMPtr();    mMsgHeaderParserFactory = null_nsCOMPtr();    mMimeURLUtilsFactory = null_nsCOMPtr();    mMimeHeadersFactory = null_nsCOMPtr();}