An intervention is when a user agent does not honor an application request for security, performance, or annoyance reasons. With this change, Chrome will both send the report to your servers using the Report-To HTTP Response header field and surface the report in the ReportingObserver interface.
Docs: https://groups.google.com/a/chromium.org/forum/#!searchin/blink-dev/sort:relevance/blink-dev/V38Q47CxTIY/vIEsirLTDwAJ https://groups.google.com/a/chromium.org/forum/#!searchin/blink-dev/sort:relevance/blink-dev/B1oztuLlzxg/tuFtADi0AgAJ