securing Google Chrome browser with a password is important for you to prevent anyone to see your passwords and history that was stored in Google Chrome browser, so to prevent anyone who does not have the password to open the browser and access to history of the sites you've visited
To lock your browser with password you have to activate the option to lock the browser with password : first open the browser and type
chrome://flags in the address bar and then press (Enter) button on the keyboard, now look for (profile management system) and activated by pressing the option (Enable) box below . And then close the browser and open it again
When you run the browser again you will notice the existence of the list at the top containing username and clicking on it will display the names of existing users of the browser, you can click on the lock icon to lock the browser and prevent its use only by entering the password, which will be the same password for your account in Google