system_api: Add the churn enums in private computing use case.

Add churn enum values in private_computing_service proto.

BUG=chromium:1405080
TEST=USE=test emerge-hatch chromeos-base/system_api

Change-Id: Ied07a2e49ff5399e7992902bd9e38086a638e0f1
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/4137196
Reviewed-by: Hirthanan Subenderan <hirthanan@google.com>
Commit-Queue: Eric Wang <qianwan@google.com>
Tested-by: Eric Wang <qianwan@google.com>
NOKEYCHECK=True
GitOrigin-RevId: 033a5d9d2f9c4bf4762eb9d171632e1a6ef8a730
diff --git a/dbus/private_computing/private_computing_service.proto b/dbus/private_computing/private_computing_service.proto
index 04edade..984f1c7 100644
--- a/dbus/private_computing/private_computing_service.proto
+++ b/dbus/private_computing/private_computing_service.proto
@@ -14,6 +14,8 @@
   CROS_FRESNEL_DAILY = 1;
   CROS_FRESNEL_FIRST_ACTIVE = 2;
   CROS_FRESNEL_28DAY_ACTIVE = 3;
+  CROS_FRESNEL_CHURN_MONTHLY_COHORT = 4;
+  CROS_FRESNEL_CHURN_MONTHLY_OBSERVATION = 5;
 }
 
 // The preserved file will include the Daily, FirstActive, 28-Day