Add new MetricsEvent for carrier demo mode dialog

Bug: 34341567
Test: manual - builds

Change-Id: Ibd9f7b2a3e857d712bbc10fd10ddf477a69267cc
diff --git a/proto/src/metrics_constants.proto b/proto/src/metrics_constants.proto
index a590805..e4b53cb 100644
--- a/proto/src/metrics_constants.proto
+++ b/proto/src/metrics_constants.proto
@@ -3388,6 +3388,9 @@
     // OS: O
     FIELD_GESTURE_VELOCITY = 827;
 
+    // OPEN: Carrier demo mode password dialog
+    CARRIER_DEMO_MODE_PASSWORD = 828;
+
     // ---- End O Constants, all O constants go above this line ----
 
     // Add new aosp constants above this line.