PrintPreview: Remove |page_number| from StartPageForVectorCanvas function.

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 42 matching lines @@
 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)
-
-  // The page number in the resulting document.  If the user is only printing
-  // page 2, |page_number| above will 1, but |page_slot| will be 0, as it's the
-  // first page in the final document.
-  IPC_STRUCT_MEMBER(int, page_slot)
 IPC_STRUCT_END()
 
 IPC_STRUCT_BEGIN(PrintMsg_PrintPages_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)
 
   // If empty, this means a request to render all the printed pages.
   IPC_STRUCT_MEMBER(std::vector<int>, pages)
 IPC_STRUCT_END()
@@ skipping 201 matching lines @@
 IPC_MESSAGE_ROUTED1(PrintHostMsg_PagesReadyForPreview,
                     PrintHostMsg_DidPreviewDocument_Params /* params */)
 
 // Tell the browser printing failed.
 IPC_MESSAGE_ROUTED1(PrintHostMsg_PrintingFailed,
                     int /* document cookie */)
 
 // Tell the browser print preview failed.
 IPC_MESSAGE_ROUTED1(PrintHostMsg_PrintPreviewFailed,
                     int /* document cookie */)