Using Google search to set a timer isn't a new feature, per se. The ability to set a timer in Google Search was around last August when Dan Graziano put together a post detailing useful tips for Google search.
But then the feature disappeared from Google search, with no mention as to why, or if it would ever return. Then, just this week, Lifehacker found the timer feature active once again on Google.com.
Setting a timer is simple; as long as you have the word "timer" and an amount of time in the search query, Google will start a timer for the requested time. You can take the timer full-screen by clicking on the box icon.
You'll need to leave the Web page open in order for the timer to work, of course.
Pretty much every device I use on a regular basis has a timer app or service, with the exception being my Mac. Instead of having to browse the Internet for yet another app, I can now use Google.com and skip an unnecessary installation.