When you're just doing poor man debugging, you can do:
LOG(ERROR) << "Simple logging";
If you want to commit logs that will be useful over time:
VLOG(1) << "[IPFS] Test";
Then when you start you can match via file paths like this:
npm start -- --vmodule=*/ipfs/*=1 --enable-logging=stderr
VLOG should be used for debug info not LOG(ERROR).
Sensitive information should never be logged at all. For example, private keys, OAuth tokens, HTTP basic auth credentials, cookies.
If logging URLs, only log origin. URLs should never be logged to disk in Private Window/Tor/Request-OTR mode.