add print to pdf for headless

headless/lib/renderer/headless_print_web_view_helper_delegate.cc

Index: headless/lib/renderer/headless_print_web_view_helper_delegate.cc
diff --git a/headless/lib/renderer/headless_print_web_view_helper_delegate.cc b/headless/lib/renderer/headless_print_web_view_helper_delegate.cc
new file mode 100644
index 0000000000000000000000000000000000000000..8afe740fe09479b826934e8b5cfe72667b7299eb
--- /dev/null
+++ b/headless/lib/renderer/headless_print_web_view_helper_delegate.cc
@@ -0,0 +1,44 @@
+// 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 {
+
+HeadlessPrintWebViewHelperDelegate::HeadlessPrintWebViewHelperDelegate() {}
+
+HeadlessPrintWebViewHelperDelegate::~HeadlessPrintWebViewHelperDelegate() {}
+
+bool HeadlessPrintWebViewHelperDelegate::CancelPrerender(
+    content::RenderFrame* render_frame) {
+  return false;
+}
+
+blink::WebElement HeadlessPrintWebViewHelperDelegate::GetPdfElement(
+    blink::WebLocalFrame* frame) {
+  return blink::WebElement();
+}
+
+bool HeadlessPrintWebViewHelperDelegate::IsPrintPreviewEnabled() {
+  return false;
+}
+
+bool HeadlessPrintWebViewHelperDelegate::OverridePrint(
+    blink::WebLocalFrame* frame) {
+  return false;
+}
+
+bool HeadlessPrintWebViewHelperDelegate::IsAskPrintSettingsEnabled() {
+  return false;
+}
+
+#if defined(OS_MACOSX)
+bool HeadlessPrintWebViewHelperDelegate::UseSingleMetafile() {
+  return true;
+}
+#endif
+
+}  // namespace headless