Hi,
I'm not sure how many different IP addresses/subnets are involved with Google but if you can create a group of IP addresses/networks then you could
- Create ACL rule and log hits to the rule in questions to your syslog server and monitor which hosts are connecting to the said IP addresses
- Create a simple traffic capture on the ASA for the said destination IP addresses and look/parse through the capture file with Wireshark for example
Those are the first two that came to mind.
- Jouni