How to view HTML source without refreshing the page in Chrome

I think none of the other answers really answer your question.

You want the exact response from the server, not the current DOM, and you want it with the exact request headers that was sent the first time.

To do so, open the Chrome Dev Tools and select the "Network" tab.

The very first request should be the page you requested. Click it and select the tab "Response" on the right side to get the exact response the server gave you.