Print Preview: Associating preview requests and responses using an identifier

chrome/common/print_messages.h

 // Copyright (c) 2011 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.
 
 // IPC messages for printing.
 // Multiply-included message file, hence no include guard.
 
 #include "base/values.h"
 #include "base/shared_memory.h"
 #include "ipc/ipc_message_macros.h"
@@ skipping 30 matching lines @@
   IPC_STRUCT_MEMBER(int, desired_dpi)
 
   // Cookie for the document to ensure correctness.
   IPC_STRUCT_MEMBER(int, document_cookie)
 
   // Should only print currently selected text.
   IPC_STRUCT_MEMBER(bool, selection_only)
 
   // Does the printer support alpha blending?
   IPC_STRUCT_MEMBER(bool, supports_alpha_blend)
+
+  IPC_STRUCT_MEMBER(int, preview_request_id)
 IPC_STRUCT_END()
 
 IPC_STRUCT_BEGIN(PrintMsg_PrintPage_Params)
   // Parameters to render the page as a printed page. It must always be the same
   // value for all the document.
   IPC_STRUCT_MEMBER(PrintMsg_Print_Params, params)
 
   // The page number is the indicator of the square that should be rendered
   // according to the layout specified in PrintMsg_Print_Params.
   IPC_STRUCT_MEMBER(int, page_number)
@@ skipping 21 matching lines @@
   IPC_STRUCT_MEMBER(uint32, data_size)
 
   // Cookie for the document to ensure correctness.
   IPC_STRUCT_MEMBER(int, document_cookie)
 
   // Store the expected pages count.
   IPC_STRUCT_MEMBER(int, expected_pages_count)
 
   // Whether the preview can be modified.
   IPC_STRUCT_MEMBER(bool, modifiable)
+
+  // The id of the preview request.
+  IPC_STRUCT_MEMBER(int, preview_request_id)
 IPC_STRUCT_END()
 
 // Parameters to describe a rendered page.
 IPC_STRUCT_BEGIN(PrintHostMsg_DidPrintPage_Params)
   // A shared memory handle to the EMF data. This data can be quite large so a
   // memory map needs to be used.
   IPC_STRUCT_MEMBER(base::SharedMemoryHandle, metafile_data_handle)
 
   // Size of the metafile data.
   IPC_STRUCT_MEMBER(uint32, data_size)
@@ skipping 147 matching lines @@
 IPC_MESSAGE_ROUTED1(PrintHostMsg_PrintingFailed,
                     int /* document cookie */)
 
 // Tell the browser print preview failed.
 IPC_MESSAGE_ROUTED1(PrintHostMsg_PrintPreviewFailed,
                     int /* document cookie */)
 
 // Tell the browser print preview was cancelled.
 IPC_MESSAGE_ROUTED1(PrintHostMsg_PrintPreviewCancelled,
                     int /* document cookie */)