service worker: Attribute purpose to start worker attempts for UMA

content/browser/geofencing/geofencing_manager.cc

Index: content/browser/geofencing/geofencing_manager.cc
diff --git a/content/browser/geofencing/geofencing_manager.cc b/content/browser/geofencing/geofencing_manager.cc
index 242b588b80d3a033373942a5edbf2ec86e12f60e..1c315bad7971763467b615a66f35b42bde9c3d8f 100644
--- a/content/browser/geofencing/geofencing_manager.cc
+++ b/content/browser/geofencing/geofencing_manager.cc
@@ -399,7 +399,8 @@ void GeofencingManager::DeliverGeofencingEvent(
                  service_worker_registration, event_type,
                  registration->region_id, registration->region,
                  make_scoped_refptr(active_version)),
-      base::Bind(&GeofencingManager::OnEventError, this));
+      base::Bind(&GeofencingManager::OnEventError, this),
+      ServiceWorkerMetrics::EventType::GEOFENCING);
 }
 
 void GeofencingManager::DeliverEventToRunningWorker(