If customization includes default wallpaper, download and apply it.

chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc

Index: chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
diff --git a/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc b/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
index f28d7831e12e690be48a742c2084b8755c8fa7b9..a8793ee5965308b7738593ab0447f1ae933c91d0 100644
--- a/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
+++ b/chrome/browser/ui/webui/chromeos/login/signin_screen_handler.cc
@@ -448,6 +448,9 @@ void SigninScreenHandler::DeclareLocalizedValues(
 void SigninScreenHandler::Show(const LoginScreenContext& context) {
   CHECK(delegate_);
 
+  // Restart fetch if previous attempt failed.
+  ServicesCustomizationDocument::GetInstance()->StartFetching();
+
   // Just initialize internal fields from context and call ShowImpl().
   oobe_ui_ = context.oobe_ui();
   if (!context.email().empty())