@afrangry @stux Yeah, on the mac I used the “Find Any File” App. I did this I think on Sunday. Many of the bits I found had been updated that day, in spite of my having deleted Chrome months ago. If you do a web search on this you can see Google does this and these embedded updaters are aggressive. Some people report bad impacts from them.

I noticed when I had an error on a backup. Checking, it was one of these files which had apparently been in the middle of updating during the backup.