What is com.onlineapplicationrequest.AppRequest?
Oops -- I posted too soon.  I have since run Malwarebytes Anti-Malware (thanks to a suggestion on my other post), and this file is identified as an instance of "Adware.Spigot".

I've been laboring under the belief that, as a Mac user who avoids the shady back alleys of the internet, I didn't have to worry about malware.  But apparently that's not quite true!