Is it still possible to lock or password-protect Chrome profiles?

You have to :

1. Enable the New Management Profile there by entering this : chrome://flags/#enable-new-profile-management in you address bar and selecting Enabled in the dropdown menu.
2. After relaunching Chrome, you have to create a supervised account in Preferences > People > Add Person, Control and view the websites this person views should be checked.

UPDATE Chrome 59.0.3071.109 (Versão oficial) 64 bits (coorte: 59_104_Win)

In Chrome 59 (at least) the flag above doesn't exist anymore, so you just need to go throught previous step 2 and be happy.

1. Create a supervised account, click in: your name (top right) > Manage People > Add People.

2. Check the checkbox for:

   Supervise this person to track and view the sites they visit using their Google Account.

3. Select your account as supervisor on the select box right below the previous checked field.

4. Don't forget to "Exit and lock" your account when you finish using the browser. For this click in: your name (top right) > Exit and lock.

Once I did that, I was able to lock Chrome.

You can achieve this by storing Chrome profile on an encrypted or removable USB drive and use Directory Junction

Steps

1. Create a new Chrome profile as you normally do.
2. Go to %LOCALAPPDATA%\Google\Chrome\User Data and locate the newly created profile folder (You can find it by sorting by Date Modified).
3. Close Chrome.
4. Move the newly created profile folder onto a secure location. e.g. a VHD file encrypted with Bitlocker or a removable drive that you have physical control.

5. Create the junction

   Suppose that the newly created profile folder is Profile 2. The secure location you copied to is F:\Profile 2

   Run the following command in Command Prompt (Win+R, cmd, OK)

   mklink /J "%LOCALAPPDATA%\Google\Chrome\User Data\Profile 2" "F:\Profile 2"

Result

Now your profile will show up in Chrome Profile list. But will not open if the profile data is not available.

You can use a Google Chrome Extension called LockPW:

LockPW is a password protection for Browser.

LockPW Free (Lock Password) Extension for Google Chrome browser allows you to set a password to activate the browser. Functional:

• Lock using the hotkey Ctrl + Shift + L
  • Manual override
  • Lock simple
  • Lock starnitsu site (Beta)
  • Limit login attempts with an action:
    1. Open a new window in incognito
    2. Delete Browsing History

You can install it on your own personal user on chrome and set it up. And if you leave your user as when you quit the chrome, the next time you open the chrome it will ask you to enter the password that you've previously entered.

And if you switch to other user while quitting chrome, it will open as normal user with no password. It works, go try it!

Unfortunately Chrome doesn't allow you to password protect user profiles anymore.

Basically, you load your Chrome Profile from an encrypted volume using Veracrypt residing in the computer or your external USB drive. When you're done, close Chrome and simply unmount the volume. You can do similar for Windows or Mac OS but specifics may differ. You may need admin privileges to mount/unmount.

Here is my setup in my Ubuntu 18.04:

First create a new User Profile in Chrome.

Open Terminal

cd ~/.config/google-chrome 
ls -al

You should see a new profile directory that is just created say, Profile 4.

Sync to your Google profile and all Chrome extensions now if you like so you know roughly how much space to allocate on the encrypted volume. Example:

du -ch 'Profile 4'

Create encrypted Veracrypt volume file

Download GUI or Console version of Veracrypt for your OS distribution.

Create encrypted volume file somewhere not so obvious example:

touch ~/.config/profile.vc

Here is an example of using Veracrypt from the Terminal to create 1 GB (check your space requirement) Ext4 encrypted volume for your User Profile. You can use the GUI version if you want.

veracrypt -t -c --volume-type=normal ~/.config/profile.vc --size=1G --encryption=aes --hash=sha-512 --filesystem=ext4 --pim=0 -k "" --random-source=/dev/urandom

You will be prompted to assign your password. Also, enter administrator password if asked.

Mount Veracrypt volume you just created. Your mount directory now becomes something like /media/veracrypt1

After mount is successful, close Veracrypt GUI if you are in a shared computer.

Exit any running Chrome applications – important!

Move chrome profile directory to your encrypted volume.

mv 'Profile 4' /media/veracrypt1/.

Create a symbolic link.

ln -s "/media/veracrypt1/Profile 4" 'Profile 4'

Open Chrome and you can now switch to your user profile from encrypted volume.

When done, quit the whole Chrome application.

Then unmount your encrypted drive from Veracrypt and open Chrome again. You'll see your extra Chrome Profile avatar but can't switch into it.

Script for convenience

Create a bash script and make it executable.

touch ~/.config/profile 
chmod +x ~/.config/profile 
vim ~/.config/profile 

Add the following to the bash file:

#!/bin/bash 
VOL=~/.config/profile.vc
if [ $1 -eq 1 ] 
then 
    echo "Mounting..." 
    veracrypt -t -k "" --pim=0 --protect-hidden=no $VOL /media/veracrypt1
    sleep 2
    nohup google-chrome --profile-directory='Profile 4' &>/dev/null &

elif [ $1 -eq 0 ]
then 
    echo "Dismounting..."
    pkill --oldest chrome
    sleep 2
    veracrypt -t -d $VOL
else
    echo "Usage: ./profile 0 or ./profile 1"
fi

Usage

To mount encrypted volume and open Chrome using your user profile

. ~/.config/profile 1    # Prompts for your password :)

To close Chrome and unmount encrypted volume

. ~/.config/profile 0