0x00 problem description
When updating apt sources with apt update today, it was exposed thatW: GPG error: http://dl.google.com/linux/chrome/deb stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 78BD65473CB3BD13
0x01 problem solving
问The essence of the problem is that the public key 78BD65473CB3BD13 is missing, just add it.
0x02 specific steps
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys <PUBKEY>