update_engine: Move DLC metadata ownership to update_engine

Add dbus messages so dlcservice can let update_engine know when a DLC is
installed or uninstalled.

BUG=chromium:912666
TEST=unittests, install and uninstall DLCs on DUT.

Cq-Depend: chromium:2112994,chromium:2113254
Change-Id: I35374504afcdaf96b099e343cabe072fc18f1022
Reviewed-on: https://chromium-review.googlesource.com/c/aosp/platform/system/update_engine/+/2113134
Reviewed-by: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Jae Hoon Kim <kimjae@chromium.org>
Tested-by: Andrew Lassalle <andrewlassalle@chromium.org>
Commit-Queue: Andrew Lassalle <andrewlassalle@chromium.org>
diff --git a/common_service.cc b/common_service.cc
index a99d10c..b94e734 100644
--- a/common_service.cc
+++ b/common_service.cc
@@ -143,6 +143,17 @@
   return true;
 }
 
+bool UpdateEngineService::SetDlcActiveValue(brillo::ErrorPtr* error,
+                                            bool is_active,
+                                            const string& dlc_id) {
+  if (!system_state_->update_attempter()->SetDlcActiveValue(is_active,
+                                                            dlc_id)) {
+    LogAndSetError(error, FROM_HERE, "SetDlcActiveValue failed.");
+    return false;
+  }
+  return true;
+}
+
 bool UpdateEngineService::GetStatus(ErrorPtr* error,
                                     UpdateEngineStatus* out_status) {
   if (!system_state_->update_attempter()->GetStatus(out_status)) {