Using Smart Lock on your Chromebook
If you are a frequent user of a Chromebook, the boot speed is very fast when you turn on your Chromebook and you must enter it each time on the sign-in screen.
The Smart Lock feature on your Chromebook is designed to ease this inconvenience. This means that if you have a smartphone near your Chromebook, you can sign in without a password.
To enable this feature, your smartphone must be at least Bluetooth-enabled Android 5.0, and your Chromebook must be Chrome OS version 40 or higher.
On your Chromebook, you'll need to select Settings menu> Show advanced settings> Use Smart Lock for Chromebook (Beta). When it is selected to use, search for a Bluetooth-enabled smartphone in the vicinity and select the desired smartphone.
After your Smart Lock setup is complete, if your smartphone is nearby and you're signed in, your Chromebook's login status will also be unlocked as shown in the screen below, in which case you can sign in directly without entering your password by clicking the login picture with your mouse. If your smartphone is logged out or powered off, your Chromebook's login will also require a password to sign in.
On your smartphone, you need to set up Settings> Security> Smart Lock> Trusted device.