add customized printing setting for headless

headless/lib/renderer/headless_print_web_view_helper_delegate.cc

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "headless/lib/renderer/headless_print_web_view_helper_delegate.h"
 
 #include "third_party/WebKit/public/web/WebElement.h"
 
 namespace headless {
 
@@ skipping 14 matching lines @@
 bool HeadlessPrintWebViewHelperDelegate::IsPrintPreviewEnabled() {
   return false;
 }
 
 bool HeadlessPrintWebViewHelperDelegate::OverridePrint(
     blink::WebLocalFrame* frame) {
   return false;
 }
 
 bool HeadlessPrintWebViewHelperDelegate::IsAskPrintSettingsEnabled() {
-  return false;
+  return true;
 }
 
 #if defined(OS_MACOSX)
 bool HeadlessPrintWebViewHelperDelegate::UseSingleMetafile() {
   return true;
 }
 #endif
 
 }  // namespace headless