Implement Windows GPO support for "dlpref" in component updater.

components/component_updater/configurator_impl.h

Index: components/component_updater/configurator_impl.h
diff --git a/components/component_updater/configurator_impl.h b/components/component_updater/configurator_impl.h
index 959a9b193b78ea975a1e38fe18b24ae70fbae4d3..09170d46962ee851d2e0d50c0d05796f774909f2 100644
--- a/components/component_updater/configurator_impl.h
+++ b/components/component_updater/configurator_impl.h
@@ -67,6 +67,10 @@ class ConfiguratorImpl {
   // XML element.
   std::string ExtraRequestParams() const;
 
+  // Provides a hint for the server to control the order in which multiple
+  // download urls are returned.
+  std::string GetDownloadPreference() const;
+
   // The source of contexts for all the url requests.
   net::URLRequestContextGetter* RequestContext() const;