Printing: Add ability to get the default printer from the print backend.

printing/backend/print_backend_win.cc

 // 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.
 
 #include "printing/backend/print_backend.h"
 
 #include <objidl.h>
 #include <winspool.h>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 24 matching lines @@
 
 namespace printing {
 
 class PrintBackendWin : public PrintBackend {
  public:
   PrintBackendWin() {}
   virtual ~PrintBackendWin() {}
 
   virtual bool EnumeratePrinters(PrinterList* printer_list);
 
+  virtual std::string GetDefaultPrinterName();
+
   virtual bool GetPrinterCapsAndDefaults(const std::string& printer_name,
                                          PrinterCapsAndDefaults* printer_info);
 
   virtual bool IsValidPrinter(const std::string& printer_name);
 };
 
 bool PrintBackendWin::EnumeratePrinters(PrinterList* printer_list) {
   DCHECK(printer_list);
   DWORD bytes_needed = 0;
   DWORD count_returned = 0;
   BOOL ret = EnumPrinters(PRINTER_ENUM_LOCAL|PRINTER_ENUM_CONNECTIONS, NULL, 2,
                           NULL, 0, &bytes_needed, &count_returned);
   if (!bytes_needed)
     return false;
   scoped_array<BYTE> printer_info_buffer(new BYTE[bytes_needed]);
   ret = EnumPrinters(PRINTER_ENUM_LOCAL|PRINTER_ENUM_CONNECTIONS, NULL, 2,
                      printer_info_buffer.get(), bytes_needed, &bytes_needed,
                      &count_returned);
   DCHECK(ret);
   if (!ret)
     return false;
 
-  // Getting the name of the default printer.
-  DWORD size = MAX_PATH;
-  TCHAR default_printer_name[MAX_PATH];
-  BOOL default_printer_exists = ::GetDefaultPrinter(
-      default_printer_name, &size);
-
+  std::string default_printer = GetDefaultPrinterName();
   PRINTER_INFO_2* printer_info =
       reinterpret_cast<PRINTER_INFO_2*>(printer_info_buffer.get());
   for (DWORD index = 0; index < count_returned; index++) {
     PrinterBasicInfo info;
     info.printer_name = WideToUTF8(printer_info[index].pPrinterName);
-    if (default_printer_exists)
-      info.is_default = (info.printer_name == WideToUTF8(default_printer_name));
+    info.is_default = (info.printer_name == default_printer);
     if (printer_info[index].pComment)
       info.printer_description = WideToUTF8(printer_info[index].pComment);
     info.printer_status = printer_info[index].Status;
     if (printer_info[index].pLocation)
       info.options[kLocationTagName] =
           WideToUTF8(printer_info[index].pLocation);
     if (printer_info[index].pDriverName)
       info.options[kDriverNameTagName] =
           WideToUTF8(printer_info[index].pDriverName);
     printer_list->push_back(info);
   }
   return true;
 }
 
+std::string PrintBackendWin::GetDefaultPrinterName() {
+  DWORD size = MAX_PATH;
+  TCHAR default_printer_name[MAX_PATH];
+  if (!::GetDefaultPrinter(default_printer_name, &size))
+    return std::string();
+  return WideToUTF8(default_printer_name);
+}
+
 bool PrintBackendWin::GetPrinterCapsAndDefaults(
     const std::string& printer_name,
     PrinterCapsAndDefaults* printer_info) {
   ScopedXPSInitializer xps_initializer;
   if (!xps_initializer.initialized()) {
     // TODO(sanjeevr): Handle legacy proxy case (with no prntvpt.dll)
     return false;
   }
   if (!IsValidPrinter(printer_name)) {
     return false;
@@ skipping 76 matching lines @@
   }
   return ret;
 }
 
 scoped_refptr<PrintBackend> PrintBackend::CreateInstance(
     const DictionaryValue* print_backend_settings) {
   return new PrintBackendWin;
 }
 
 }  // namespace printing