As the first step in an effort to improve robustness of the cloud print proxy...

chrome/service/cloud_print/print_system.h

 // Copyright (c) 2010 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.
 
 #ifndef CHROME_SERVICE_CLOUD_PRINT_PRINT_SYSTEM_H_
 #define CHROME_SERVICE_CLOUD_PRINT_PRINT_SYSTEM_H_
 #pragma once
 
 #include <map>
 #include <string>
 #include <vector>
 
+#include "base/callback.h"
 #include "base/ref_counted.h"
 
 #include "printing/backend/print_backend.h"
 
 class DictionaryValue;
 class FilePath;
 
 namespace printing {
 class PrintBackend;
 struct PrinterBasicInfo;
@@ skipping 100 matching lines @@
     // or Delegate::OnJobSpoolFailed methods are called) can fail.
     virtual bool Spool(const std::string& print_ticket,
                        const FilePath& print_data_file_path,
                        const std::string& print_data_mime_type,
                        const std::string& printer_name,
                        const std::string& job_title,
                        const std::vector<std::string>& tags,
                        JobSpooler::Delegate* delegate) = 0;
   };
 
+  typedef Callback3<
+      bool,
+      const std::string&,
+      const printing::PrinterCapsAndDefaults&>::Type
+          PrinterCapsAndDefaultsCallback;
+
   virtual ~PrintSystem();
 
   // Initialize print system. This need to be called before any other function
   // of PrintSystem.
   virtual void Init() = 0;
 
   // Enumerates the list of installed local and network printers.
   virtual void EnumeratePrinters(printing::PrinterList* printer_list) = 0;
 
-  // Gets the capabilities and defaults for a specific printer.
-  virtual bool GetPrinterCapsAndDefaults(
+  // Gets the capabilities and defaults for a specific printer asynchronously.
+  virtual void GetPrinterCapsAndDefaults(
       const std::string& printer_name,
-      printing::PrinterCapsAndDefaults* printer_info) = 0;
+      PrinterCapsAndDefaultsCallback* callback) = 0;
 
   // Returns true if printer_name points to a valid printer.
   virtual bool IsValidPrinter(const std::string& printer_name) = 0;
 
   // Returns true if ticket is valid.
   virtual bool ValidatePrintTicket(const std::string& printer_name,
                                    const std::string& print_ticket_data) = 0;
 
   // Get details for already spooled job.
   virtual bool GetJobDetails(const std::string& printer_name,
@@ skipping 22 matching lines @@
 // Visual Studio where it gets confused between multiple Delegate
 // classes and gives a C2500 error. (I saw this error on the try bots -
 // the workaround was not needed for my machine).
 typedef PrintSystem::PrintServerWatcher::Delegate PrintServerWatcherDelegate;
 typedef PrintSystem::PrinterWatcher::Delegate PrinterWatcherDelegate;
 typedef PrintSystem::JobSpooler::Delegate JobSpoolerDelegate;
 
 }  // namespace cloud_print
 
 #endif  // CHROME_SERVICE_CLOUD_PRINT_PRINT_SYSTEM_H_