User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Firefox/31.0 (Beta/Release) Build ID: 20140716183446 Steps to reproduce: Upgraded to FF version 31.0. Actual results: A significant portion of the newtab page is taken by a Google search bar. Expected results: Presumably exactly that. However, I'd appreciate it being informed of the controls available to me, i.e. through about:config, to turn it off.

There is currently no option to remove it. There's a bug filed to add such an option, so I'm marking this as a duplicate of that bug.

You can remove it trough some hacks, see the original bug linked in comment above. And a tip: you can search bugs to see if they are already reported. But don't worry, marking as duplicate isn't hard. :)