[Night Light] CL2: Ash and system tray work

ash/metrics/user_metrics_recorder.cc

Index: ash/metrics/user_metrics_recorder.cc
diff --git a/ash/metrics/user_metrics_recorder.cc b/ash/metrics/user_metrics_recorder.cc
index a6ff35eafe6f271c10eeb30f26cd1d2f4cf67d29..a28b656b04e519a80ca18e49b0ffbeefb579d6c1 100644
--- a/ash/metrics/user_metrics_recorder.cc
+++ b/ash/metrics/user_metrics_recorder.cc
@@ -547,6 +547,9 @@ void UserMetricsRecorder::RecordUserMetricsAction(UserMetricsAction action) {
     case UMA_TRAY_LOCK_SCREEN:
       RecordAction(UserMetricsAction("Tray_LockScreen"));
       break;
+    case UMA_TRAY_NIGHT_LIGHT:
+      RecordAction(UserMetricsAction("Tray_NightLight"));
+      break;
     case UMA_TRAY_OVERVIEW:
       RecordAction(UserMetricsAction("Tray_Overview"));
       break;