add print to pdf for headless

headless/lib/renderer/headless_print_web_view_helper_delegate.h

Index: headless/lib/renderer/headless_print_web_view_helper_delegate.h
diff --git a/headless/lib/renderer/headless_print_web_view_helper_delegate.h b/headless/lib/renderer/headless_print_web_view_helper_delegate.h
new file mode 100644
index 0000000000000000000000000000000000000000..691974c029b03f39f4a9b802ae2a8297158b61b6
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+++ b/headless/lib/renderer/headless_print_web_view_helper_delegate.h
@@ -0,0 +1,32 @@
+// 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.
+
+#ifndef HEADLESS_LIB_RENDERER_HEADLESS_PRINT_WEB_VIEW_HELPER_DELEGATE_H_
+#define HEADLESS_LIB_RENDERER_HEADLESS_PRINT_WEB_VIEW_HELPER_DELEGATE_H_
+
+#include "components/printing/renderer/print_web_view_helper.h"
+
+namespace headless {
+
+class HeadlessPrintWebViewHelperDelegate
+    : public printing::PrintWebViewHelper::Delegate {
+ public:
+  HeadlessPrintWebViewHelperDelegate();
+  ~HeadlessPrintWebViewHelperDelegate() override;
+
+  // PrintWebViewHelper Delegate implementation.
+  bool CancelPrerender(content::RenderFrame* render_frame) override;
+  bool IsPrintPreviewEnabled() override;
+  bool OverridePrint(blink::WebLocalFrame* frame) override;
+  bool IsAskPrintSettingsEnabled() override;
+  blink::WebElement GetPdfElement(blink::WebLocalFrame* frame) override;
+
+#if defined(OS_MACOSX)
+  bool UseSingleMetafile() override;
+#endif
+};
+
+}  // namespace headless
+
+#endif  // HEADLESS_LIB_RENDERER_HEADLESS_PRINT_WEB_VIEW_HELPER_DELEGATE_H_