How to Reset Google Keys in Debian Apt  
When doing apt-get update and having google packages installed (google earth, chrome, chrome-remote-desktop, etc), you may sometimes get some error of the sort:
W: GPG error: stable Release: The following signatures were invalid: KEYEXPIRED D38B4796  KEYEXPIRED 7FAC5991
This can be fixed by deleting the keys and reinstalling them:
sudo apt-key del D38B4796
sudo apt-key del 7FAC5991
wget -q -O - | sudo apt-key add -
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