update_engine: Add powerwash flag to update status

Add a powerwash flag to the update status which is set to true if and
only if a powerwash takes place. This will ensure that the user is
informed of a pending powerwash exactly when it is going to happen.

BUG=chromium:1070563
TEST=FEATURES=test emerge-amd64-generic update_engine
channel change and update on test device

Cq-Depend: chromium:2187671
Change-Id: I58314ecc7c9c2e64c906ef5b31cb780948196296
Reviewed-on: https://chromium-review.googlesource.com/c/aosp/platform/system/update_engine/+/2187672
Reviewed-by: Jae Hoon Kim <kimjae@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
Tested-by: Miriam Polzer <mpolzer@google.com>
Commit-Queue: Miriam Polzer <mpolzer@google.com>
diff --git a/update_attempter.cc b/update_attempter.cc
index 0ead18a..6324a48 100644
--- a/update_attempter.cc
+++ b/update_attempter.cc
@@ -1507,6 +1507,12 @@
   system_state_->prefs()->GetString(kPrefsOmahaEolDate, &str_eol_date);
   out_status->eol_date = StringToEolDate(str_eol_date);
 
+  // A powerwash will take place either if the install plan says it is required
+  // or if an enterprise rollback is happening.
+  out_status->will_powerwash_after_reboot =
+      install_plan_ &&
+      (install_plan_->powerwash_required || install_plan_->is_rollback);
+
   return true;
 }