On all versions of Windows, Chrome usually updates automatically and silently using a process titled GoogleUpdate.exe. There's no way to uninstall the updater other than removing Chrome, so unless something goes wrong with the updater, the browser always stays up to date. If you ever do need a manual update, Chrome colors the Menu button and inserts an update button in the menu.
Google Update checks for new versions of Chrome every five hours, as long as your computer is online. The updater runs in the background on your computer from the moment you turn it on, so your browser stays up to date even if you don't open it. During regular day-to-day use, there's almost never any need to check for updates manually.
If Chrome does fall out of date, such as if the GoogleUpdate.exe process crashes or if you prevent it from running when the system boots, you'll see the Menu icon in Chrome change colors. Normally gray, the icon progresses through green, yellow and red as the browser becomes two, four and seven days out of date. When you notice the color change, open the menu and click Update Google Chrome to update. To see the current version and force an update check when the color hasn't changed, click About Google Chrome instead.
The Chrome app for Android and iOS only updates automatically if you have your apps set to auto-update. To update Chrome on your phone or tablet, download the new version from Google Play or the App Store.