Domain Reliability: Add was_proxied field to beacons.

components/domain_reliability/monitor.cc

Index: components/domain_reliability/monitor.cc
diff --git a/components/domain_reliability/monitor.cc b/components/domain_reliability/monitor.cc
index bd86ad9d4f0f23e4a21d546cb8ac7dd78a8057a4..83a6af19252425f7ee953bfe87d6b4c074500883 100644
--- a/components/domain_reliability/monitor.cc
+++ b/components/domain_reliability/monitor.cc
@@ -280,6 +280,7 @@ void DomainReliabilityMonitor::OnRequestLegComplete(
   beacon.http_response_code = response_code;
   beacon.start_time = request.load_timing_info.request_start;
   beacon.elapsed = time_->NowTicks() - beacon.start_time;
+  beacon.was_proxied = request.response_info.was_fetched_via_proxy;
   beacon.domain = request.url.host();
   context_manager_.RouteBeacon(request.url, beacon);
 }