im not sure you can deserialize the proto data within chrome itself, but you can easily do it with mitmproxy, install it and start a instance using "mitmweb",setup a system wide proxy to point to localhost and mitmweb port(default is 8080), mitmweb should deserialize the data automatically, if not, copy the hexdump of the request or response you're interested in,to and head over to cyberchef, decode the data from hexdump and use proto decode, make sure to remove the first 3-n bytes based on the message length, it should decode it successfully