This is a new test added in https://chromium-review.googlesource.com/c/chromium/src/+/916901.

With NetworkService it fails because two expected output lines are missing:
--- /b/s/w/io9W1jrX/layout-test-results/http/tests/inspector-protocol/network/request-interception-raw-headers-expected.txt
+++ /b/s/w/io9W1jrX/layout-test-results/http/tests/inspector-protocol/network/request-interception-raw-headers-actual.txt
@@ -6,8 +6,6 @@
 Runtime agent enabled
 Response.requestHeadersText present: true
 Connection raw header present: true
-Network.requestIntercepted ID 1 GET simple-iframe.html type: Document
-allowRequest ID 1
 Network.responseReceived simple-iframe.html 200 text/html
 Page.frameStoppedLoading

The linked  bug 806281  mentions " we're currently working on re-implementing support for the interception on a different level (it's going to be a proxy for URLLoader/URLLoaderFactory interfaces, so it will be involved on a higher level of network service rather than under net stack)." so I suspect this is expected for now. I'll add expectations or mark the test failing.