Google has been talking about making SSL a ranking factor since 2014 with the latest update of Chrome. Google will start calling out none HTTPS site as unsafe.
This is from the Google BlogWebmaster level: all
Security is a top priority for Google. We invest a lot in making sure that our services use industry-leading security, like strong HTTPS encryption by default. That means that people using Search, Gmail and Google Drive, for example, automatically have a secure connection to Google.