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_status_utils_unittest.cc b/update_status_utils_unittest.cc
index dbd80d7..3af30c7 100644
--- a/update_status_utils_unittest.cc
+++ b/update_status_utils_unittest.cc
@@ -24,22 +24,11 @@
 
 namespace chromeos_update_engine {
 
-TEST(UpdateStatusUtilsTest, UpdateEngineStatusToStringDefaultTest) {
-  string print =
-      R"(CURRENT_OP=UPDATE_STATUS_IDLE
-IS_INSTALL=false
-LAST_CHECKED_TIME=0
-NEW_SIZE=0
-NEW_VERSION=
-PROGRESS=0.0
-)";
-  EXPECT_EQ(print, UpdateEngineStatusToString({}));
-}
-
 TEST(UpdateStatusUtilsTest, UpdateEngineStatusToStringTest) {
   update_engine::UpdateEngineStatus update_engine_status = {
       .status = update_engine::UpdateStatus::CHECKING_FOR_UPDATE,
       .is_install = true,
+      .is_enterprise_rollback = true,
       .last_checked_time = 156000000,
       .new_size_bytes = 888,
       .new_version = "12345.0.0",
@@ -47,6 +36,7 @@
   };
   string print =
       R"(CURRENT_OP=UPDATE_STATUS_CHECKING_FOR_UPDATE
+IS_ENTERPRISE_ROLLBACK=true
 IS_INSTALL=true
 LAST_CHECKED_TIME=156000000
 NEW_SIZE=888