Good question. Probably all they know is that Microsoft released a competing browser and just asked the engineering team to do them a tool for showing annoying messages to the users based on the browser. I am sure marketing doesn't know/care if it was done with Chromium, 1994 Mosaic or matchsticks.

This is Google we are talking about. I would imagine they started working on competing strategies even well before Microsoft announced officially they are going to use Chromium.

You people seriously undermine the tech awareness of marketing teams, of Google no less.

This reeks of smug engineering superiority.

I promise you the marketing team does serious competitive intel and probably knows more about the competitive landscape than the engineers themselves. That's true at my place of employment (also a bay area tech company), and I'd be shocked if it's not true at Google.