Implement notificationclose event

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 c1d3699ddaf3580577fadf5723d339c8b38eb4f3..6b74eaf09254c9514960b78e0f864f525f00922b 100644
--- a/content/browser/service_worker/service_worker_metrics.cc
+++ b/content/browser/service_worker/service_worker_metrics.cc
@@ -58,6 +58,8 @@ const char* ServiceWorkerMetrics::EventTypeToString(EventType event_type) {
       return "Sync";
     case EventType::NOTIFICATION_CLICK:
       return "Notification Click";
+    case EventType::NOTIFICATION_CLOSE:
+      return "Notification Close";
     case EventType::PUSH:
       return "Push";
     case EventType::GEOFENCING:
@@ -226,6 +228,10 @@ void ServiceWorkerMetrics::RecordEventDuration(EventType event,
       UMA_HISTOGRAM_MEDIUM_TIMES("ServiceWorker.NotificationClickEvent.Time",
                                  time);
       break;
+    case EventType::NOTIFICATION_CLOSE:
+      UMA_HISTOGRAM_MEDIUM_TIMES("ServiceWorker.NotificationCloseEvent.Time",
+                                 time);
+      break;
     case EventType::PUSH:
       UMA_HISTOGRAM_MEDIUM_TIMES("ServiceWorker.PushEvent.Time", time);
       break;