Add proto for USB default screen

Bug: 62876645
Test: none
Change-Id: I08de7910c9d7f62760edfcfca24a9807606d7346
diff --git a/proto/src/metrics_constants.proto b/proto/src/metrics_constants.proto
index e118c49..7e86ef5 100644
--- a/proto/src/metrics_constants.proto
+++ b/proto/src/metrics_constants.proto
@@ -5278,6 +5278,11 @@
     // OS: P
     FIELD_QS_MODE = 1311;
 
+    // OPEN: Settings->Developer Options->Default USB
+    // CATEGORY: SETTINGS
+    // OS: P
+    USB_DEFAULT = 1312;
+
     // ---- End P Constants, all P constants go above this line ----
     // Add new aosp constants above this line.
     // END OF AOSP CONSTANTS