Google introduced a built-in timer command last year, but then mysteriously dumped it after a few days. Now the timer is back.
You can set the timer by typing any of the following commands into the Google search box (or directly into your address bar if your default search is set to Google, which is usually the case in Chrome):
set timer 45 seconds set timer 10 minutes 30 seconds set timer an hour and a half set timer 12 hours 6 minutes 3 seconds
If you simply type
set timer, you'll see an option for five minutes. The word
set is also optional.
Google Operating System notes that the option currently only works with desktop search -- but most mobile devices have a timer built into the clock app anyway.
Google's Timer Is Back [Google Operating System]