HTTPS-filtering toggle canary. Loads a known HTTPS tracker subresource
(googletagmanager.com/gtag/js) and reports whether the browser loaded
it. The verdict's expected value depends on the runtime's
filter_encrypted_traffic state, so the test runner — not this page —
interprets pass/fail.
HttpsFilteringToggleTests in
Adblock.ReleaseTests. The runner verdicts off the CDP
Network.responseReceived status code for the
gtm.js subresource (204 = blocked, 200 = allowed) and
pairs that with a CDP securityDetails capture to verify
the cert chain matches the toggle position (spoofed Adblock
CA-issued leaf when on; real googletagmanager.com chain
when off).