HRESULT XUserGetTokenAndSignatureUtf16Async(  
         XUserHandle user,  
         XUserGetTokenAndSignatureOptions options,  
         const wchar_t* method,  
         const wchar_t* url,  
         size_t headerCount,  
         const XUserGetTokenAndSignatureUtf16HttpHeader* headers,  
         size_t bodySize,  
         const void* bodyBuffer,  
         XAsyncBlock* async  
)