update_engine: Rename policy values of DeviceRollbackToTargetVersion

Rename the following values for better understanding and
consistency:
- RollbackWithFullPowerwash to RollbackAndPowerwash
- RollbackWithRestoreOnly to RollbackOnlyIfRestorePossible

BUG=chromium:878736
TEST='cros_run_unit_tests --board=caroline --packages update_engine'

Change-Id: Ib4129d2c297697e850d3027d35599fc37e104b0e
Reviewed-on: https://chromium-review.googlesource.com/1198533
Commit-Ready: Marton Hunyady <hunyadym@chromium.org>
Tested-by: Marton Hunyady <hunyadym@chromium.org>
Reviewed-by: Sen Jiang <senj@chromium.org>
diff --git a/update_manager/boxed_value_unittest.cc b/update_manager/boxed_value_unittest.cc
index b15a504..99d578c 100644
--- a/update_manager/boxed_value_unittest.cc
+++ b/update_manager/boxed_value_unittest.cc
@@ -203,19 +203,20 @@
             BoxedValue(
                 new RollbackToTargetVersion(RollbackToTargetVersion::kDisabled))
                 .ToString());
-  EXPECT_EQ("Rollback with full powerwash",
+  EXPECT_EQ("Rollback and powerwash",
             BoxedValue(new RollbackToTargetVersion(
-                           RollbackToTargetVersion::kRollbackWithFullPowerwash))
+                           RollbackToTargetVersion::kRollbackAndPowerwash))
                 .ToString());
   EXPECT_EQ(
       "Rollback and restore if possible",
       BoxedValue(new RollbackToTargetVersion(
                      RollbackToTargetVersion::kRollbackAndRestoreIfPossible))
           .ToString());
-  EXPECT_EQ("Rollback with restore only",
-            BoxedValue(new RollbackToTargetVersion(
-                           RollbackToTargetVersion::kRollbackWithRestoreOnly))
-                .ToString());
+  EXPECT_EQ(
+      "Rollback only if restore is possible",
+      BoxedValue(new RollbackToTargetVersion(
+                     RollbackToTargetVersion::kRollbackOnlyIfRestorePossible))
+          .ToString());
 }
 
 TEST(UmBoxedValueTest, SetConnectionTypeToString) {