I like Firefox a lot and I also have chromium.
I sometimes use chromium for being practical and having some extensions that Firefox doesn't.
I don't know the mechanics of gnome-keyring but from my perspective it's a master-key prompt login to decrypt other saved passwords.
One big difference about Mozilla Firefox and Chromium is that Firefox by default will not ask a master-key every time you open the browser after boot (only for those who have auto-login with no password enabled).
Chromium uses gnome-keyring so every time I open it, it will annoy me to insert the master-key password.
The thing is, I can press Esc key or choose Cancel in the window above and the effect will be the same - it will still continue to write my saved passwords automatically.
What is the use of asking for a master-key password if you can press Esc and the effect will be the same?