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

chrome/service/cloud_print/print_system_cups.cc

Index: chrome/service/cloud_print/print_system_cups.cc
===================================================================
--- chrome/service/cloud_print/print_system_cups.cc	(revision 72357)
+++ chrome/service/cloud_print/print_system_cups.cc	(working copy)
@@ -28,9 +28,11 @@
 #include "chrome/service/cloud_print/cloud_print_consts.h"
 #include "chrome/service/cloud_print/cloud_print_helpers.h"
 #include "googleurl/src/gurl.h"
+#include "grit/generated_resources.h"
 #include "printing/backend/cups_helper.h"
 #include "printing/backend/print_backend.h"
 #include "printing/backend/print_backend_consts.h"
+#include "ui/base/l10n/l10n_util.h"
 
 namespace {
 static const char kCUPSPrinterInfoOpt[] = "printer-info";
@@ -73,7 +75,8 @@
   // PrintSystem implementation.
   virtual PrintSystemResult Init();
 
-  virtual void EnumeratePrinters(printing::PrinterList* printer_list);
+  virtual PrintSystem::PrintSystemResult EnumeratePrinters(
+      printing::PrinterList* printer_list);
 
   virtual void GetPrinterCapsAndDefaults(
       const std::string& printer_name,
@@ -151,6 +154,9 @@
 
   int update_timeout_;
   bool initialized_;
+  // A comma separated string of print server names for which enumeration of
+  // printers failed. This is used to prepare a diagnostic error message.
+  std::string enum_failed_server_list_;

[gene1, 2011/01/24 19:46:47]

Can we keep it as a bool flag?
I understand that in the future we might want to report a list of servers, but
in that case I would prefer to keep the list of failed servers and convert them
to the comma-separated list right before sending to the upper level.

[Scott Byer, 2011/01/24 20:02:07]

Since it's not being used, how about making it a bool for now?

 };
 
 class PrintServerWatcherCUPS
@@ -412,8 +418,12 @@
 
 void PrintSystemCUPS::UpdatePrinters() {
   PrintServerList::iterator it;
+  enum_failed_server_list_.clear();
   for (it = print_servers_.begin(); it != print_servers_.end(); ++it) {
-    it->backend->EnumeratePrinters(&it->printers);
+    if (!it->backend->EnumeratePrinters(&it->printers)) {
+      enum_failed_server_list_.append(it->url.spec());
+      enum_failed_server_list_.append(",");
+    }
     it->caps_cache.clear();
     printing::PrinterList::iterator printer_it;
     for (printer_it = it->printers.begin();
@@ -431,7 +441,8 @@
       GetUpdateTimeoutMs());
 }
 
-void PrintSystemCUPS::EnumeratePrinters(printing::PrinterList* printer_list) {
+PrintSystem::PrintSystemResult PrintSystemCUPS::EnumeratePrinters(
+    printing::PrinterList* printer_list) {
   DCHECK(initialized_);
   printer_list->clear();
   PrintServerList::iterator it;
@@ -440,6 +451,13 @@
         it->printers.begin(), it->printers.end());
   }
   VLOG(1) << "CUPS: Total " << printer_list->size() << " printers enumerated.";
+  if (!enum_failed_server_list_.empty()) {
+    // The enumeration failed on some servers.
+    // TODO(sanjeevr): Maybe some day we want to report the actual server names.
+    std::string message = l10n_util::GetStringUTF8(IDS_CLOUD_PRINT_ENUM_FAILED);
+    return PrintSystemResult(false, message);
+  }
+  return PrintSystemResult(true, std::string());
 }
 
 void PrintSystemCUPS::GetPrinterCapsAndDefaults(