Printing: Load the source PDF only once.

chrome/utility/printing_handler.h

 // Copyright 2014 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 CHROME_UTILITY_PRINTING_HANDLER_H_
 #define CHROME_UTILITY_PRINTING_HANDLER_H_
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "build/build_config.h"
@@ skipping 18 matching lines @@
  public:
   PrintingHandler();
   ~PrintingHandler() override;
 
   // IPC::Listener:
   bool OnMessageReceived(const IPC::Message& message) override;
 
  private:
   // IPC message handlers.
 #if defined(OS_WIN)
-  void OnRenderPDFPagesToMetafile(IPC::PlatformFileForTransit pdf_transit,
+  void OnRenderPDFPagesToMetafileStart(IPC::PlatformFileForTransit pdf_transit,
                                   const PdfRenderSettings& settings,
                                   bool print_text_with_gdi);
   void OnRenderPDFPagesToMetafileGetPage(
       int page_number,
       IPC::PlatformFileForTransit output_file);
   void OnRenderPDFPagesToMetafileStop();
 #endif  // OS_WIN
 #if BUILDFLAG(ENABLE_PRINT_PREVIEW)
   void OnRenderPDFPagesToPWGRaster(IPC::PlatformFileForTransit pdf_transit,
                                    const PdfRenderSettings& settings,
@@ skipping 13 matching lines @@
                                  const PwgRasterSettings& bitmap_settings,
                                  base::File bitmap_file);
 
   void OnGetPrinterCapsAndDefaults(const std::string& printer_name);
   void OnGetPrinterSemanticCapsAndDefaults(const std::string& printer_name);
 #endif  // ENABLE_PRINT_PREVIEW
 
 #if defined(OS_WIN)
   std::vector<char> pdf_data_;
   PdfRenderSettings pdf_rendering_settings_;
+  void* pdf_handle_ = nullptr;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(PrintingHandler);
 };
 
 }  // namespace printing
 
 #endif  // CHROME_UTILITY_PRINTING_HANDLER_H_