Printing: Load the source PDF only once.

chrome/common/chrome_utility_printing_messages.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.
 
 // Multiply-included message file, so no include guard.
 
 #include <string>
 #include <vector>
 
 #include "base/strings/string16.h"
@@ skipping 81 matching lines @@
 IPC_MESSAGE_CONTROL1(ChromeUtilityMsg_GetPrinterSemanticCapsAndDefaults,
                      std::string /* printer name */)
 #endif  // ENABLE_PRINT_PREVIEW
 
 // Windows uses messages for printing even without preview. crbug.com/170859
 // Primary user of Windows without preview is CEF. crbug.com/417967
 #if BUILDFLAG(ENABLE_PRINTING) && defined(OS_WIN)
 // Tell the utility process to start rendering the given PDF into a metafile.
 // Utility process would be alive until
 // ChromeUtilityMsg_RenderPDFPagesToMetafiles_Stop message.
-IPC_MESSAGE_CONTROL3(ChromeUtilityMsg_RenderPDFPagesToMetafiles,
+IPC_MESSAGE_CONTROL3(ChromeUtilityMsg_RenderPDFPagesToMetafiles_Start,
                      IPC::PlatformFileForTransit /* input_file */,
                      printing::PdfRenderSettings /* settings */,
                      bool /* print_text_with_gdi */)
 
 // Requests conversion of the next page.
 IPC_MESSAGE_CONTROL2(ChromeUtilityMsg_RenderPDFPagesToMetafiles_GetPage,
                      int /* page_number */,
                      IPC::PlatformFileForTransit /* output_file */)
 
 // Requests utility process to stop conversion and exit.
@@ skipping 48 matching lines @@
                      float /* scale_factor */)
 
 // Request that the given font characters be loaded by the browser so it's
 // cached by the OS. Please see
 // PdfToEmfUtilityProcessHostClient::OnPreCacheFontCharacters for details.
 IPC_SYNC_MESSAGE_CONTROL2_0(ChromeUtilityHostMsg_PreCacheFontCharacters,
                             LOGFONT /* font_data */,
                             base::string16 /* characters */)
 
 #endif  // ENABLE_PRINTING && OS_WIN