Add ServiceWorker.NavigationPreload.HeaderSize UMA

content/browser/service_worker/service_worker_metrics.cc

Index: content/browser/service_worker/service_worker_metrics.cc
diff --git a/content/browser/service_worker/service_worker_metrics.cc b/content/browser/service_worker/service_worker_metrics.cc
index aca38b992cbb47ccc9902e4dd28fab7141eba192..d7c7533ba4e44a18343b1a8bae02344fd40a70c3 100644
--- a/content/browser/service_worker/service_worker_metrics.cc
+++ b/content/browser/service_worker/service_worker_metrics.cc
@@ -761,4 +761,10 @@ void ServiceWorkerMetrics::RecordStartStatusAfterFailure(
   }
 }
 
+void ServiceWorkerMetrics::RecordNavigationPreloadRequestHeaderSize(
+    size_t size) {
+  UMA_HISTOGRAM_COUNTS_100000("ServiceWorker.NavigationPreload.HeaderSize",
+                              size);
+}
+
 }  // namespace content