add print to pdf for headless

headless/app/headless_shell.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.
 
 #include "base/files/file_proxy.h"
 #include "base/memory/weak_ptr.h"
 #include "headless/app/shell_navigation_request.h"
 #include "headless/public/devtools/domains/emulation.h"
 #include "headless/public/devtools/domains/inspector.h"
 #include "headless/public/devtools/domains/page.h"
@@ skipping 45 matching lines @@
 
   void InputExpression();
 
   void OnExpressionResult(std::unique_ptr<runtime::EvaluateResult> result);
 
   void CaptureScreenshot();
 
   void OnScreenshotCaptured(
       std::unique_ptr<page::CaptureScreenshotResult> result);
 
-  void OnScreenshotFileOpened(
-      std::unique_ptr<page::CaptureScreenshotResult> result,
-      const base::FilePath file_name,
-      base::File::Error error_code);
+  void PrintToPDF();
 
-  void OnScreenshotFileWritten(const base::FilePath file_name,
-                               const int length,
-                               base::File::Error error_code,
-                               int write_result);
+  void OnPDFCreated(std::unique_ptr<page::PrintToPDFResult> result);
 
-  void OnScreenshotFileClosed(base::File::Error error_code);
+  void WriteFile(const std::string& switch_string,
+                 const std::string& default_file_name,
+                 const std::string& data);
+  void OnFileOpened(const std::string& data,
+                    const base::FilePath file_name,
+                    base::File::Error error_code);
+  void OnFileWritten(const base::FilePath file_name,
+                     const int length,
+                     base::File::Error error_code,
+                     int write_result);
+  void OnFileClosed(base::File::Error error_code);
 
   bool RemoteDebuggingEnabled() const;
 
   HeadlessDevToolsClient* devtools_client() const {
     return devtools_client_.get();
   }
 
  private:
   GURL url_;
   HeadlessBrowser* browser_;  // Not owned.
   std::unique_ptr<HeadlessDevToolsClient> devtools_client_;
   HeadlessWebContents* web_contents_;
   bool processed_page_ready_;
-  std::unique_ptr<base::FileProxy> screenshot_file_proxy_;
+  std::unique_ptr<base::FileProxy> file_proxy_;
   HeadlessBrowserContext* browser_context_;
   std::unique_ptr<DeterministicDispatcher> deterministic_dispatcher_;
   base::WeakPtrFactory<HeadlessShell> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(HeadlessShell);
 };
 
 }  // namespace headless