why did my old history and extensions appear in a fresh install of chrome?

Question

I uninstalled chrome with:

sudo apt-get purge google-chrome-stable

The next day I reinstalled it with:

sudo apt-get install google-chrome-stable

All the old settings from the old install appeared when I opened it up.

Answer 1

None of those commands removes any files in your $HOME directory.

When you apt-get remove apt will leave the (system) configuration files in /etc in place. When you apt-get purge apt will remove the (system) configuration files in /etc as well.

remove
       remove is identical to install except that packages are removed
       instead of installed. Note the removing a package leaves its
       configuration files in system. If a plus sign is appended to the
       package name (with no intervening space), the identified package
       will be installed instead of removed.
purge
       purge is identical to remove except that packages are removed and
       purged (any configuration files are deleted too).

See http://manpages.ubuntu.com/manpages/jaunty/man8/apt-get.8.html for details

Neither option will remove configuration files in your home ($HOME) directory, those have to be removed manually.

Thus when you re-installed it reused all the files you already have.

To remove all that additional stuff run

rm -rf ~/.config/google-chrome