Your Safari browser is hijacked. What to do next ?

I got a call from a friend today. He said he was surfing the net on his Macbook and a popup told him to install an update to Adobe reader so he clicked on it. That's when the trouble started. It's obvious that this malware was meant for Windows users but it still locked up his Macbook browser making it unusable. He had no other alternate browser installed. So to get him out of this jam I talked him through the following steps to get his browser working again.

1. If Safari has been hijacked...

Your Safari browser is hijacked. What to do next ?