Google Chrome is a great browser when it comes to speed, but it does not provide the ability by default to lock a tab so that it does not get closed accidently. But recently there is new google chrome extension released named Lock Tabs, it allows you to lock tabs in google chrome so that you might not close them by mistake.
After installing this add on in google chrome it will display a cool blue coloured symbol in address bar, which you can click to make a tab permanent or sticky.
After locking a tab in google chrome when ever you try to close it, it will prompt you that the tab has been locked so that you can avoid closing this tab un intentionally. [ as shown in the image below ]
Still if you want to close this tab then click the button Leave this Page