C++ random generator mt19937, is it in

I've confirmed from here and (more definitively) here that you need to #include<random> to use std::mt19937, but when I do this in CLion, CLion flags it red and suggests that it's in <bits/random.h>. So which one is it? Am I supposed to #include both? But I thought header files with .h extension are deprecated?

By the way I'm using CLion 1.2.1 with GCC 4.8.3 on CentOS Linux release 7.1.1503.