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/omaha_request_params.cc b/omaha_request_params.cc
index 4b72328..c458424 100644
--- a/omaha_request_params.cc
+++ b/omaha_request_params.cc
@@ -123,7 +123,7 @@
   // Set the interactive flag accordingly.
   interactive_ = in_interactive;
 
-  dlc_ids_.clear();
+  dlc_module_ids_.clear();
   // Set false so it will do update by default.
   is_install_ = false;
   return true;