I have a Rails 4.2.6 application running. In some of my pages, I use iframe to put Google Map Embedded api to show maps of some locations. My whole website is https secured using letsencrypt. However the pages that use google map api always get a "Not Secure" warning from Chrome or Firefox. When I remove the google map iframes, the warning disappears.
I have googled a lot and there is a workaround in here using meta tag. The workaround is an HTML format, but I still don't know how to put the meta tag to my rails application. The keyword seems to be "upgrade-insecure-requests".
Please help, thank you .