service worker: Add a netlog event for navigation preload

content/browser/loader/resource_dispatcher_host_impl.cc

Index: content/browser/loader/resource_dispatcher_host_impl.cc
diff --git a/content/browser/loader/resource_dispatcher_host_impl.cc b/content/browser/loader/resource_dispatcher_host_impl.cc
index e2bf1492e47e1b1d8807f68690ad91d13b7f5c37..90ed1ce30ae58f909973c8347dac8a4a9f14c956 100644
--- a/content/browser/loader/resource_dispatcher_host_impl.cc
+++ b/content/browser/loader/resource_dispatcher_host_impl.cc
@@ -102,6 +102,7 @@
 #include "net/http/http_request_headers.h"
 #include "net/http/http_response_headers.h"
 #include "net/http/http_response_info.h"
+#include "net/log/net_log_with_source.h"
 #include "net/ssl/client_cert_store.h"
 #include "net/ssl/ssl_cert_request_info.h"
 #include "net/url_request/url_request.h"
@@ -1227,6 +1228,15 @@ void ResourceDispatcherHostImpl::ContinuePendingBeginRequest(
                                    : request_data.url,
       request_data.priority, nullptr);
 
+  // Log that this request is a service worker navigation preload request here,
+  // since navigation preload machinery has no access to netlog.
+  // TODO(falken): Figure out how mojom::URLLoaderClient can
+  // access the request's netlog.
+  if (requester_info->IsNavigationPreload()) {
+    new_request->net_log().AddEvent(
+        net::NetLogEventType::SERVICE_WORKER_NAVIGATION_PRELOAD_REQUEST);
+  }
+
   // PlzNavigate: Always set the method to GET when gaining access to the
   // stream that contains the response body of a navigation. Otherwise the data
   // that was already fetched by the browser will not be transmitted to the