The native string type on Windows is a UTF-16 string. This matches our base::string16 type. I notice that there are spots in the notifications code where strings obtained from the OS (e.g., command lines) are converted to ASCII and then passed around as std::strings. I think it would be an improvement to stick with string16 (at least in Win-specific code) to reduce the number of conversions and to remove any confusion about when to use ASCII vs UTF8.