Hii @kartik,
got the same error using:
<link rel="stylesheet" href="//fonts.googleapis.com/css?family=Source+Sans+Pro:400,400i,700,700i,900,900i" type="text/css" media="all">
But once I added https: in the beginning of the href the error disappeared.
<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Source+Sans+Pro:400,400i,700,700i,900,900i" type="text/css" media="all">
Hope this is helpful!!
Thank you!!