update_engine: fix english

Fix the english for accuracy regarding DLC.

BUG=chromium:897882
TEST=None

Change-Id: I72ab9ecb7903bb5fb35597222cd7c8b1f4244cfc
Reviewed-on: https://chromium-review.googlesource.com/1351359
Commit-Ready: Xiaochu Liu <xiaochu@chromium.org>
Tested-by: Xiaochu Liu <xiaochu@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
diff --git a/update_attempter_unittest.cc b/update_attempter_unittest.cc
index 676f13a..a395e1b 100644
--- a/update_attempter_unittest.cc
+++ b/update_attempter_unittest.cc
@@ -1185,8 +1185,8 @@
                            testing::Return(true)));
 
   attempter_.CheckForUpdate("", "autest", UpdateAttemptFlags::kNone);
-  EXPECT_EQ(attempter_.dlc_ids_.size(), 1);
-  EXPECT_EQ(attempter_.dlc_ids_[0], dlc_module_id);
+  EXPECT_EQ(attempter_.dlc_module_ids_.size(), 1);
+  EXPECT_EQ(attempter_.dlc_module_ids_[0], dlc_module_id);
 }
 
 TEST_F(UpdateAttempterTest, CheckForUpdateAUTest) {