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

chrome/service/cloud_print/printer_job_handler.h

Index: chrome/service/cloud_print/printer_job_handler.h
===================================================================
--- chrome/service/cloud_print/printer_job_handler.h	(revision 72042)
+++ chrome/service/cloud_print/printer_job_handler.h	(working copy)
@@ -91,6 +91,10 @@
      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 true if the printer should be deleted from the server,
+     // false otherwise.
+     virtual bool OnPrinterNotFound(const std::string& printer_name) = 0;
 
    protected:
      virtual ~Delegate() {}