Add extensions code to use common updater in components/update_client/

components/component_updater/configurator_impl.cc

Index: components/component_updater/configurator_impl.cc
diff --git a/components/component_updater/configurator_impl.cc b/components/component_updater/configurator_impl.cc
index cc6d7f0c4b1df5105475c563ca69795ec85fbfde..fb8f1dbf30442176f235fdc8b983becb94b6c673 100644
--- a/components/component_updater/configurator_impl.cc
+++ b/components/component_updater/configurator_impl.cc
@@ -192,4 +192,8 @@ bool ConfiguratorImpl::UseBackgroundDownloader() const {
   return background_downloads_enabled_;
 }
 
+void ConfiguratorImpl::set_enable_alt_source_url(bool enable_alt_source_url) {
+  fallback_to_alt_source_url_enabled_ = enable_alt_source_url;
+}
+
 }  // namespace component_updater