Google Search Console just sent me an email about a particular website I own that says:
Starting October 2017, Chrome (version 62) will show a “NOT SECURE” warning when users enter text in a form on an HTTP page, and for all HTTP pages in Incognito mode.
I know from past experience that when things like this happen a lot of customers will see the "NOT SECURE" warning and freak out. Nothing is technically changing, it's just Google Chrome making sure that you're aware of the fact that the data you transmit might be susceptible to a hacker listening in on your connection to that website.
All too often I have seen clients who pick up the phone in the middle of the night and call their "web guy" to make them aware of the notification that Chrome just gave them. So my advice if you own a web agency or manage websites for any type of clients (and you don't want to get a rude email/phone call from your clients) - make sure you have an SSL installed on their website, if that website contains a form. If you manage websites that don't contain any forms - then you're all good. However, Google still may not be ranking you as high in the SERPs if you don't have an SSL.