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 f32a0916099756054dcdcf6bb0973e3eee108550..5bfdf96ec8bebcdc9407ee3345a1a3a07273c0cc 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:
@@ -234,6 +236,8 @@ void ServiceWorkerMetrics::RecordEventDuration(EventType event,
     case EventType::FETCH:
     // For now event duration for these events is not recorded.
     case EventType::GEOFENCING:
+    // TODO(nsatragno): create UMA metric.
+    case EventType::NOTIFICATION_CLOSE:
     case EventType::SERVICE_PORT_CONNECT:
     case EventType::MESSAGE:
       break;