HRESULT XLaunchUri(  
         XUserHandle requestingUser,  
         const char* uri  
)  

HRESULT BeginPlayingMusic(XUserHandle user)
{
    // Launch a well-known companion music application.
    // The game and app both need to agree on the URI scheme.
    HRESULT hr = XLaunchUri(user, "ms-bgm-companion-music-app://launch?play=true");
    if (hr == E_GAMEPACKAGE_NO_PACKAGE_IDENTIFIER)
    {
        // If the music app isn't installed, launch the store page so the user can download it.
        return XLaunchUri(user, "ms-windows-store://pdp/?ProductId=9FAKESTOREID");
    }

    return hr;
}