To prevent the dialog "Enter password for keyring 'Default keyring' to unlock" always pop-up, you can assign a blank password to keyring.
Be careful -
By choosing to use a blank password, your stored passwords will not be safely encrypted. They will be accessible by anyone with access to your files.
Run Setting - Passwords and Keys
Right click "Default keyring" and "Change Password"
Enter old password
Leave blank in new password