Comment # 30 on bug 1008325 from Peter Tselios

This is marked as fixed. However, in Leap 42.3 I still have the same issue. 
My libzypp is: 
libzypp-16.17.4-15.1.x86_64

However:
zypper ref

Retrieving repository 'google-chrome' metadata
---------------------------------------------------------------------------------------------------------------[/]
Warning: File 'repomd.xml' from repository 'google-chrome' is signed with an
unknown key '1397BC53640DB551'.

    Note: Signing data enables the recipient to verify that no modifications
occurred after the data
    were signed. Accepting data with no, wrong or unknown signature can lead to
a corrupted system
    and in extreme cases even to a system compromise.

    Note: File 'repomd.xml' is the repositories master index file. It ensures
the integrity of the
    whole repo.

    Warning: We can't verify that no one meddled with this file, so it might
not be trustworthy
    anymore! You should not continue unless you know it's safe.

File 'repomd.xml' from repository 'google-chrome' is signed with an unknown key
'1397BC53640DB551'. Continue? [yes/no] (no): 

FYI, I had removed all Google keys and I added them manually:

wget https://dl-ssl.google.com/linux/linux_signing_key.pub
rpm --import linux_signing_key.pub