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_engine_client.cc b/update_engine_client.cc
index 9d1e093..f36949b 100644
--- a/update_engine_client.cc
+++ b/update_engine_client.cc
@@ -296,7 +296,7 @@
   DEFINE_bool(last_attempt_error, false, "Show the last attempt error.");
   DEFINE_bool(eol_status, false, "Show the current end-of-life status.");
   DEFINE_bool(install, false, "Requests an install.");
-  DEFINE_string(dlc_ids, "", "colon-separated list of DLC IDs.");
+  DEFINE_string(dlc_module_ids, "", "colon-separated list of DLC IDs.");
 
   // Boilerplate init commands.
   base::CommandLine::Init(argc_, argv_);
@@ -481,24 +481,26 @@
   }
 
   if (FLAGS_install) {
-    // Parse DLC IDs.
-    vector<string> dlc_ids;
-    if (!FLAGS_dlc_ids.empty()) {
-      dlc_ids = base::SplitString(
-          FLAGS_dlc_ids, ":", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
+    // Parse DLC module IDs.
+    vector<string> dlc_module_ids;
+    if (!FLAGS_dlc_module_ids.empty()) {
+      dlc_module_ids = base::SplitString(FLAGS_dlc_module_ids,
+                                         ":",
+                                         base::TRIM_WHITESPACE,
+                                         base::SPLIT_WANT_ALL);
     }
-    if (dlc_ids.empty()) {
-      LOG(ERROR) << "dlc_ids is empty:" << FLAGS_dlc_ids;
+    if (dlc_module_ids.empty()) {
+      LOG(ERROR) << "dlc_module_ids is empty:" << FLAGS_dlc_module_ids;
       return 1;
     }
-    if (!client_->AttemptInstall(FLAGS_omaha_url, dlc_ids)) {
+    if (!client_->AttemptInstall(FLAGS_omaha_url, dlc_module_ids)) {
       LOG(ERROR) << "AttemptInstall failed.";
       return 1;
     }
     return 0;
-  } else if (!FLAGS_dlc_ids.empty()) {
-    LOG(ERROR) << "dlc_ids is not empty while install is not set:"
-               << FLAGS_dlc_ids;
+  } else if (!FLAGS_dlc_module_ids.empty()) {
+    LOG(ERROR) << "dlc_module_ids is not empty while install is not set:"
+               << FLAGS_dlc_module_ids;
     return 1;
   }