Google Chrome uses Gnome 'login' keyring to securely store passwords. It is usually protected by a password that matches your login password. Gnome keyring can automatically unlock it when the user logs in. When you login normally, the system gives the password you just entered to gnome-keyring, which then unlocks the login keyring.
So, why am I being asked to unlock a "keyring"?
The 'login' keyring password does not match your login password
When the user changes their password, the PAM module changes the password of the 'login' keyring to match.
If root changes the password, or /etc/shadow is directly edited then due to the lack of the old password, the 'login' keyring cannot be updated.
You have to update the 'login' keyring password manually.
You did not enter your password when logging in
When you have auto-login enabled or use another passwordless authentication method (for example 'fingerprint' device), you don't enter any password, and gnome-keyring cannot unlock the keyring automatically. So it asks you to unlock it.
If you have enabled disk encryption, LUKS passphrase can be reused to decrypt GNOME keyring even with auto-login. This works in Fedora out of box, but propably requires additional configuration tweaks in Ubuntu and Arch to configure initramfs to use systemd (and, therefore, systemd-cryptsetup).
Overwise, if you want to have auto-login and auto-unlock,
you need to remove the keyring's password (set it to a blank one).