Implement CUP signing in UpdateClient.

BUG=583027

Review URL: https://codereview.chromium.org/1685323002

Cr-Commit-Position: refs/heads/master@{#375930}
diff --git a/components/component_updater/configurator_impl.cc b/components/component_updater/configurator_impl.cc
index 35c1793a..6372118 100644
--- a/components/component_updater/configurator_impl.cc
+++ b/components/component_updater/configurator_impl.cc
@@ -178,4 +178,8 @@
   return background_downloads_enabled_;
 }
 
+bool ConfiguratorImpl::UseCupSigning() const {
+  return true;
+}
+
 }  // namespace component_updater