add print to pdf for headless

headless/lib/browser/headless_print_manager.h

+// 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_BROWSER_HEADLESS_PRINT_MANAGER_H_
+#define HEADLESS_LIB_BROWSER_HEADLESS_PRINT_MANAGER_H_
+
+#include <memory>
+#include <string>
+
+#include "components/printing/browser/print_manager.h"
+#include "content/public/browser/render_frame_host.h"
+#include "content/public/browser/web_contents_user_data.h"
+
+struct PrintHostMsg_DidPrintPage_Params;
+
+namespace printing {
+
+class HeadlessPrintManager
+    : public PrintManager,
+      public content::WebContentsUserData<HeadlessPrintManager> {
+ public:
+  enum PrintResult {
+    kPrintSuccess,

[Lei Zhang, 2017/03/29 05:30:16]

Chromium C++ style diverges slightly from Google style here due to historic
reasons. So these should be MACRO_STYLE.
https://chromium.googlesource.com/chromium/src/+/master/styleguide/c++/c++.md

[jzfeng, 2017/03/30 03:04:57]

Done.

+    kPrintingFailed,
+    kInvalidPrinterSettings,
+    kInvalidMemoryHandle,
+    kMetafileMapError,
+    kUnexpectedValidMemoryHandle,
+    kMetafileInvalidHeader,
+    kMetafileGetDataError,
+    kDuplicatedPrintingError,

[Eric Seckler, 2017/03/29 11:21:20]

nit: kSimultaneousPrintActive?

[jzfeng, 2017/03/30 03:04:57]

Done.

+  };
+
+  using GetPDFCallback = base::Callback<void(PrintResult, const std::string&)>;
+
+  ~HeadlessPrintManager() override;
+
+  static std::string PrintResultToErrMsg(PrintResult result);
+  static std::unique_ptr<base::DictionaryValue> PDFContentsToDictionaryValue(
+      const std::string& data);
+
+  // Prints the current document immediately. Since the rendering is
+  // asynchronous, the actual printing will not be completed on the return of
+  // this function.

[Lei Zhang, 2017/03/29 05:30:16]

You may want to say |callback| will always get called when printing finishes.

[jzfeng, 2017/03/30 03:04:57]

Done.

+  void GetPDFContents(content::RenderFrameHost* rfh,
+                      const GetPDFCallback& callback);
+
+ private:
+  explicit HeadlessPrintManager(content::WebContents* web_contents);
+  friend class content::WebContentsUserData<HeadlessPrintManager>;
+
+  // content::WebContentsObserver implementation.
+  bool OnMessageReceived(const IPC::Message& message,
+                         content::RenderFrameHost* render_frame_host) override;
+
+  // IPC Message handlers.
+  void OnGetDefaultPrintSettings(IPC::Message* reply_msg);
+  void OnShowInvalidPrinterSettingsError();
+  void OnPrintingFailed(int cookie) override;
+  void OnDidPrintPage(const PrintHostMsg_DidPrintPage_Params& params);
+
+  void Reset();
+  void ReleaseJob(PrintResult result);
+
+  content::RenderFrameHost* printing_rfh_;
+  GetPDFCallback callback_;
+  std::string data_;
+  bool is_active_;

[Lei Zhang, 2017/03/29 05:30:16]

You may want to just remove this and check if |callback_| is_null() instead.
You'll need to call callback_.Reset() in Reset() for that to work.

[jzfeng, 2017/03/30 03:04:57]

Cool! Done.

+
+#if !defined(OS_MACOSX)
+  // Set to true when OnDidPrintPage() should be expecting the first page.
+  bool expecting_first_page_;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(HeadlessPrintManager);
+};
+
+}  // namespace printing
+
+#endif  // HEADLESS_LIB_BROWSER_HEADLESS_PRINT_MANAGER_H_