Oh, I didn't think of that. But I don't think that's really true either. There seem to be ads on the homepage before Chrome:
Google News: https://web.archive.org/web/20021001073516/http://www.google...
Google Calendar: https://web.archive.org/web/20060831050142/http://www.google...
For comparison, Chrome: https://web.archive.org/web/20080904192205/http://www.google...
Now admittedly the Chrome one is a bit flashier. Although I haven't exhaustively gone through every homepage variant before Chrome, so it's possible there was something as flashy before Chrome as well.