Is this malware? Chromium browser update needed…

I can’t work this one out.  I’ve Googled around the web, but not found anything.  Periodically, I get the following image pop up on my Windows 10 PC:

Update Required

It reads:

Update Required

Your version of Yahoo search is out of date.

There is a newer and improved version available with the fresh and intuitive Chromium browser.  By clicking “OK” you agree to Install Chromium browser as your default browser, install our Desktop search bar, set Yahoo provided search as your default search, homepage and new tab on all of your compatible browsers.

I don’t want any of that! I also don’t use Yahoo search (so I don’t really think this is from Yahoo), which is why I wonder if it is malware.  Windows Defender does not seem to pick anything up.