[sushid]

Thankfully, Chrome has a built-in feature to prevent this from happening (on OSX at least). Just go to Chrome > Warn before Quitting and make sure there's a checkmark next to the option.

Now, if you accidentally press Cmd + Q, it should prompt a "Hold Cmd + Q to Quit" instead of actually quitting.

[tremendo]

Or, Settings > On Startup... "Continue where you left off". This will restore your tabs after launching Chrome.

[Houshalter]

I disabled that warning because it's annoying every time I want to close the browser, even without the dangerous keyboard shortcut. If it happens, you can go to the menu and find "recent tabs" or just ctrl+shift+t.