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

ios/chrome/browser/component_updater/ios_component_updater_configurator.cc

Index: ios/chrome/browser/component_updater/ios_component_updater_configurator.cc
diff --git a/ios/chrome/browser/component_updater/ios_component_updater_configurator.cc b/ios/chrome/browser/component_updater/ios_component_updater_configurator.cc
index f196385c8f9b7ffe5c79aec8e8110d00762543ac..1c1025c3cfa4d8ca2dc6fb67cc8fcd6750400a49 100644
--- a/ios/chrome/browser/component_updater/ios_component_updater_configurator.cc
+++ b/ios/chrome/browser/component_updater/ios_component_updater_configurator.cc
@@ -36,6 +36,7 @@ class IOSConfigurator : public update_client::Configurator {
   std::string GetLang() const override;
   std::string GetOSLongName() const override;
   std::string ExtraRequestParams() const override;
+  std::string GetDownloadPreference() const override;
   net::URLRequestContextGetter* RequestContext() const override;
   scoped_refptr<update_client::OutOfProcessPatcher> CreateOutOfProcessPatcher()
       const override;
@@ -105,6 +106,10 @@ std::string IOSConfigurator::ExtraRequestParams() const {
   return configurator_impl_.ExtraRequestParams();
 }
 
+std::string IOSConfigurator::GetDownloadPreference() const {
+  return configurator_impl_.GetDownloadPreference();
+}
+
 net::URLRequestContextGetter* IOSConfigurator::RequestContext() const {
   return configurator_impl_.RequestContext();
 }