update_engine: Pass is_enterprise_rollback in the StatusResult

Currently Chrome uses some sort of version comparison to define whether
an update is a rollback or not. But that is not very robust. The correct
way is the return this value in the StatusResult. We already have this
value as a placeholder in the update_engine.proto. So this is good to
go.

BUG=chromium:864672
TEST=FEATUERS=test emerge-reef update_engine

Change-Id: I8bd3af0d94abd656dc00a9e67550ea6c6913de91
Reviewed-on: https://chromium-review.googlesource.com/c/aosp/platform/system/update_engine/+/1775116
Tested-by: Amin Hassani <ahassani@chromium.org>
Commit-Queue: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Jae Hoon Kim <kimjae@chromium.org>
diff --git a/update_attempter.cc b/update_attempter.cc
index 71463b5..780ba7b 100644
--- a/update_attempter.cc
+++ b/update_attempter.cc
@@ -1382,6 +1382,8 @@
   out_status->progress = download_progress_;
   out_status->new_size_bytes = new_payload_size_;
   out_status->new_version = new_version_;
+  out_status->is_enterprise_rollback =
+      install_plan_ && install_plan_->is_rollback;
   out_status->is_install = is_install_;
   return true;
 }