Disable secure DNS for captive portal probes.

Bug: 10161646
Change-Id: I66061df5533dc00e8c07e354098f6735f366a3c1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1870492
Commit-Queue: Katharine Daly <dalyk@google.com>
Reviewed-by: Matt Menke <mmenke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#710962}

components/captive_portal/captive_portal_detector.cc

@@ -90,6 +90,12 @@ void CaptivePortalDetector::StartProbe(
   resource_request->load_flags = net::LOAD_BYPASS_CACHE;
   resource_request->credentials_mode = network::mojom::CredentialsMode::kOmit;
 
+  // Secure DNS should be disabled for captive portal probes so that when a
+  // captive portal is present, the DNS lookup for the probe domain succeeds or
+  // is intercepted.
+  resource_request->trusted_params = network::ResourceRequest::TrustedParams();
+  resource_request->trusted_params->disable_secure_dns = true;
+
   simple_loader_ = network::SimpleURLLoader::Create(std::move(resource_request),
                                                     traffic_annotation);
   simple_loader_->SetAllowHttpErrorResults(true);