add print to pdf for headless

headless/app/headless_shell.h

Index: headless/app/headless_shell.h
diff --git a/headless/app/headless_shell.h b/headless/app/headless_shell.h
index 4b0e83f6cbf3e5dd9f19b495af98d69e60599296..8d8a859cebb3ffdbca9bc120668122c5ad819055 100644
--- a/headless/app/headless_shell.h
+++ b/headless/app/headless_shell.h
@@ -63,17 +63,21 @@ class HeadlessShell : public HeadlessWebContents::Observer,
   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 OnScreenshotFileWritten(const base::FilePath file_name,
-                               const int length,
-                               base::File::Error error_code,
-                               int write_result);
-
-  void OnScreenshotFileClosed(base::File::Error error_code);
+  void PrintToPDF();
+
+  void OnPDFCreated(std::unique_ptr<page::PrintToPDFResult> result);
+
+  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;
 
@@ -87,7 +91,7 @@ class HeadlessShell : public HeadlessWebContents::Observer,
   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_;