Blocking Adult Content
An easy solution would be changing the DNS server used by your device, by using a DNS server that doesn't resolve porn website hostnames.

You might need a rooted device to change the DNS.

An universal method to change the DNS is by using an app like SetDNS or  OverrideDNS.

Other methods for changing DNS is available here:
(GUIDE) How to Change DNS in Android Device (7 methods)

A few DNS servers that don't resolve porn websites are:


OpenDNS:
208.67.222.123
208.67.220.123
Norton:
199.85.126.20
199.85.127.20


More here:
Source - 5 DNS Services to Block Porn Sites without Installing Software