Add metrics to track auto-brightness settings UI.

This tracks when the UI is displayed/hidden.

Bug: 69795935
Test: build
Change-Id: I9caf913b04735470d1aea9fe6b30a91aaf55cf29
diff --git a/proto/src/metrics_constants.proto b/proto/src/metrics_constants.proto
index 2e4c3b8..89bf608 100644
--- a/proto/src/metrics_constants.proto
+++ b/proto/src/metrics_constants.proto
@@ -5613,6 +5613,11 @@
     // OS: P
     SETTINGS_ZEN_ONBOARDING = 1380;
 
+    // OPEN: Settings > Display > Auto brightness
+    // CATEGORY: SETTINGS
+    // OS: P
+    SETTINGS_AUTO_BRIGHTNESS = 1381;
+
     // ---- End P Constants, all P constants go above this line ----
 
     // First Q constant in master goes here: