Selenium based malware (malvertising) checking - A few questions
a. Reviewing the Safe Browsing API Terms of Service together with the Google APIs Terms of Service I cannot find anything that you are doing that falls outside of these.
b. The docs consistently refer to URL rather than domain - having performed some tests (e.g. liderlab.ru / absa/ vs. liderlab.ru /absa / page/ 1) the first is a phising site and gives the appropriate warning whereas the second doesn't).
c. PhishTank is good and free and seems to be a little more current than Google (from a brief investigation). BrightCloud is a reasonably priced pay for service. URL Blacklist is a pay for service that works on a honour system so you can see their data.