Add metrics constant for feature flag UI

Bug: 36222960
Test: builds
Change-Id: I7726ff827db6d47d5fd1e5a1c8ef65e9e4c1254a
diff --git a/proto/src/metrics_constants.proto b/proto/src/metrics_constants.proto
index ae25932..8e747d9 100644
--- a/proto/src/metrics_constants.proto
+++ b/proto/src/metrics_constants.proto
@@ -4334,6 +4334,10 @@
     // CATEGORY: SETTINGS
     ACTION_MOBILE_NETWORK_SET_UP_DATA_SERVICE = 1155;
 
+    // OPEN: Settings > Developer Options > Experiment dashboard
+    // CATEGORY: SETTINGS
+    SETTINGS_FEATURE_FLAGS_DASHBOARD = 1156;
+
     // Add new aosp constants above this line.
     // END OF AOSP CONSTANTS
   }