Add metric for Smart battery page.

Bug: 71502850
Test: Build
Change-Id: I08082b96f0bae1472db1f13ef89488fb08be21b7
diff --git a/proto/src/metrics_constants.proto b/proto/src/metrics_constants.proto
index 1aaa538..4f04d36 100644
--- a/proto/src/metrics_constants.proto
+++ b/proto/src/metrics_constants.proto
@@ -5124,6 +5124,11 @@
     // OS: P
     ACTION_USB_CONFIG_ACCESSORY = 1280;
 
+    // OPEN: Settings > Battery > Smart Battery
+    // CATEGORY: SETTINGS
+    // OS: P
+    FUELGAUGE_SMART_BATTERY = 1281;
+
     // ---- End P Constants, all P constants go above this line ----
     // Add new aosp constants above this line.
     // END OF AOSP CONSTANTS