The default locations of Chrome's profile directory are defined at http://www.chromium.org/user-experience/user-data-directory. For Chrome on Mac, it's
~/Library/Application\ Support/Google/Chrome/Default
--user-data-dir=path/to/directoryDefault/Extensions/Extensions
If that didn't help, you can always do a custom search.
find . -type d -iname jifpbeccnghkjeaalbbjmodiffmgedin