RefCounted types should not have public destructors, printing/ and ui/

printing/backend/print_backend_cups.cc

Index: printing/backend/print_backend_cups.cc
diff --git a/printing/backend/print_backend_cups.cc b/printing/backend/print_backend_cups.cc
index ae0c5532402cc64fc8f5af2489f10491122c48c8..9bba09a74cec67170c2e7126b515a629ef84da27 100644
--- a/printing/backend/print_backend_cups.cc
+++ b/printing/backend/print_backend_cups.cc
@@ -103,22 +103,20 @@ static const char kCUPSPrinterMakeModelOpt[] = "printer-make-and-model";
 class PrintBackendCUPS : public PrintBackend {
  public:
   PrintBackendCUPS(const GURL& print_server_url, bool blocking);
-  virtual ~PrintBackendCUPS() {}
 
   // PrintBackend implementation.
   virtual bool EnumeratePrinters(PrinterList* printer_list) OVERRIDE;
-
   virtual std::string GetDefaultPrinterName() OVERRIDE;
-
   virtual bool GetPrinterCapsAndDefaults(
       const std::string& printer_name,
       PrinterCapsAndDefaults* printer_info) OVERRIDE;
-
   virtual std::string GetPrinterDriverInfo(
       const std::string& printer_name) OVERRIDE;
-
   virtual bool IsValidPrinter(const std::string& printer_name) OVERRIDE;
 
+ protected:
+  virtual ~PrintBackendCUPS() {}
+
  private:
   // Following functions are wrappers around corresponding CUPS functions.
   // <functions>2()  are called when print server is specified, and plain