Added a diagnostic user message when enumerating printers fails. Also tweaked...

chrome/service/cloud_print/printer_job_handler.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_PRINTER_JOB_HANDLER_H_
 #define CHROME_SERVICE_CLOUD_PRINT_PRINTER_JOB_HANDLER_H_
 #pragma once
 
 #include <list>
 #include <string>
@@ skipping 73 matching lines @@
     std::string print_data_mime_type_;
     std::vector<std::string> tags_;
   };
 
  public:
   class Delegate {
    public:
      virtual void OnPrinterJobHandlerShutdown(
         PrinterJobHandler* job_handler, const std::string& printer_id) = 0;
      virtual void OnAuthError() = 0;
+     // Called when the PrinterJobHandler cannot find the printer locally. The
+     // delegate returns |delete_from_server| to true if the printer should be
+     // deleted from the server,false otherwise.
+     virtual void OnPrinterNotFound(const std::string& printer_name,
+                                    bool* delete_from_server) = 0;
 
    protected:
      virtual ~Delegate() {}
   };
 
   struct PrinterInfoFromCloud {
     std::string printer_id;
     std::string caps_hash;
     std::string tags_hash;
   };
@@ skipping 187 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(PrinterJobHandler);
 };
 
 // This typedef is to workaround the issue with certain versions of
 // 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 PrinterJobHandler::Delegate PrinterJobHandlerDelegate;
 
 #endif  // CHROME_SERVICE_CLOUD_PRINT_PRINTER_JOB_HANDLER_H_