The latest version of Chrome (39) introduced some annoying behavior when revealing and hiding the top bar, so annoying that I wrote up a bug report, and decided to keep using the previous version (37). But I kept getting this warning when starting the application:

Your profile can not be used because it is from a newer version of Google Chrome. Some features may be unavailable. Please specify a different profile directory or use a newer version of Chrome.

And my search settings (for which I have a lot of nifty shortcuts) were vaporized every time.

Here’s how I solved that problem:

cd ~/Library/Application Support/Google/Chrome/Default
mv Web\ Data Web\ Data.old

The warning is gone, and upon signing in to Chrome, my search settings were restored.