Chrome Version: 62.0.3202.62 (Official Build) (64-bit)
OS Version: Windows 10 Pro

What steps will reproduce the problem?
1. Visit a page with a CSP violation and a report-uri specified so a report is sent.
2. Add an event listener for SecurityPolicyViolation events and process the event.
3. You can't prevent the browser sending its own CSP report.

What is the expected result?
You should be able to process the event yourself and stop the browser from sending a report.

What happens instead of that?
The browser always sends its own CSP report.

UserAgentString: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.62 Safari/537.36