TRON logging for TextView gesture - Long press.

Bug: 32572232
Test: Manually confirmed that stats were sent for logging by checking
  adb logs according to go/tron-howto.
Change-Id: I1ea09174190247c219ce42f70c7db75148033685
diff --git a/proto/src/metrics_constants.proto b/proto/src/metrics_constants.proto
index 9b4b186..45f2ec7 100644
--- a/proto/src/metrics_constants.proto
+++ b/proto/src/metrics_constants.proto
@@ -2653,6 +2653,12 @@
     // OS: O
     ENTERPRISE_PRIVACY_SETTINGS = 628;
 
+    // ACTION: Longpress on a TextView.
+    //  SUBTYPE: 1 is for START_SELECTION, 2 is for START_DRAG_AND_DROP, 0 is for OTHER.
+    // CATEGORY: TEXT_CONTROLS
+    // OS: O
+    TEXT_LONGPRESS = 629;
+
     // ---- End O Constants, all O constants go above this line ----
 
     // Add new aosp constants above this line.