Tron/proto: Add ACTION and FIELD for logging the boot reason string value through metrics.

Bug: 63584589
Test: None
Change-Id: Iad6941df5a357e3a1471d446e9776d8412d9e215
(cherry picked from commit b1dc6ca8c9)

proto/src/metrics_constants.proto

@@ -4311,6 +4311,14 @@ message MetricsEvent {
     // OS: O MR
     FIELD_SETTINGS_SMART_SUGGESTIONS_ENABLED = 1097;
 
+    // ACTION: The device boots
+    ACTION_BOOT = 1098;
+
+    // FIELD: A string value representing some state of the platform, e.g., boot reason
+    FIELD_PLATFORM_REASON = 1099;
+
+    // ---- End O-MR1 Constants, all O-MR1 constants go above this line ----
+
     // Add new aosp constants above this line.
     // END OF AOSP CONSTANTS
   }