Resource-Freshness header is sent when a revalidation request is initiated by the Blink memory cache within the stale-while-revalidate window. On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". PASS FAIL resourceFreshnessHeader is "max-age=0,stale-while-revalidate=1,age=1" should be max-age=0,stale-while-revalidate=1,age=1. Was max-age=0,stale-while-revalidate=1,age=2. PASS successfullyParsed is true TEST COMPLETE