Chrome: We're big fans of the Noisli web app, which allows you to create background noise so you can focus on your work. The new Chrome extension works the same way, but you don't need to keep that extra tab open to use it.
The Chrome extension connects to the web app, so all the noise generation combos you've saved there are accessible from the extension. You can also set up a timer if you like to use Noisli as a motivator for work. If you're a user of the web app or the iOS app, the extension works between them all.
Noisli (Free) [Chrome Web Store]