Use file handles to interact with utility process.

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 "ipc/ipc_message_macros.h"
@@ skipping 103 matching lines @@
 // Reply when the utility process has failed to obtain the printer
 // semantic capabilities and defaults.
 IPC_MESSAGE_CONTROL1(
   ChromeUtilityHostMsg_GetPrinterSemanticCapsAndDefaults_Failed,
   std::string /* printer name */)
 
 #endif  // ENABLE_FULL_PRINTING
 
 #if defined(OS_WIN)
 // Tell the utility process to render the given PDF into a metafile.
-// The metafile path will have ".%d" inserted where the %d is the page number.
-// If no page range is specified, all pages will be converted.
-IPC_MESSAGE_CONTROL4(ChromeUtilityMsg_RenderPDFPagesToMetafiles,
-                     IPC::PlatformFileForTransit,  // PDF file
-                     base::FilePath,  // Base location for output metafile
-                     printing::PdfRenderSettings,  // PDF render settings
-                     std::vector<printing::PageRange>)
+IPC_MESSAGE_CONTROL2(ChromeUtilityMsg_RenderPDFPagesToMetafiles,

[Lei Zhang, 2014/09/15 21:49:53]

BTW, this should go in the "Utility process messages" section between lines
60-86.

[Vitaly Buka (NO REVIEWS), 2014/09/15 22:33:50]

Done.

+                     IPC::PlatformFileForTransit, /* input_file */
+                     printing::PdfRenderSettings /* settings */)
 
-// Reply when the utility process has succeeded in rendering the PDF.
-IPC_MESSAGE_CONTROL2(ChromeUtilityHostMsg_RenderPDFPagesToMetafiles_Succeeded,
-                     std::vector<printing::PageRange>,  // Pages rendered
-                     double)                            // Scale factor
+// Reply when the utility process has succeeded in rendering the PDF page.
+IPC_MESSAGE_CONTROL1(ChromeUtilityHostMsg_RenderPDFPagesToMetafiles_PageCount,
+                     int /* page_count */)
 
-// Reply when an error occurred rendering the PDF.
-IPC_MESSAGE_CONTROL0(ChromeUtilityHostMsg_RenderPDFPagesToMetafile_Failed)
+// Requests conversion of the next page.
+IPC_MESSAGE_CONTROL2(ChromeUtilityHostMsg_RenderPDFPagesToMetafiles_GetPage,

[Lei Zhang, 2014/09/15 21:49:53]

This should be a ChromeUtilityMsg and go in the above section.

[Vitaly Buka (NO REVIEWS), 2014/09/15 22:33:50]

Done.

+                     int /* page_number */,
+                     IPC::PlatformFileForTransit /* output_file */)
 
+// Reply when the utility process has succeeded in rendering the PDF page.
+IPC_MESSAGE_CONTROL2(ChromeUtilityHostMsg_RenderPDFPagesToMetafiles_PageDone,
+                     bool /* success */,
+                     double /* scale_factor */)
 #endif  // OS_WIN