Basically, while in Gmail, if you're reading an email with an email signature, it will detect this & then check your address book to see that contact can be improved. (all of this in just a few seconds)
1) Go to the Chrome Tool/Settings button in the very top right of your browser, then choose "more tools", then "Extensions".
2) Go to the Evercontact section & click on "options" just underneath the tool.
3) Click "Display in Gmail" and then "save".
4) Now go back to Gmail & reload your browser.
Go to an email that has an email signature & wait a few seconds until you see the contact pop-up in the top right of Gmail as you see below:
5) At this point, you'll see that it will work on any email that you're reading & give you the possibility to save/edit contact details at any point (and to confirm that your contacts are beautifully updated otherwise!).