4 files changed, 30 insertions, 31 deletions
diff --git a/printing/backend/print_backend.h b/printing/backend/print_backend.h
index 8e28b2d..84a9d90 100644
--- a/printing/backend/print_backend.h
+++ b/printing/backend/print_backend.h
@@ -53,8 +53,6 @@ struct PRINTING_EXPORT PrinterCapsAndDefaults {
 class PRINTING_EXPORT PrintBackend
     : public base::RefCountedThreadSafe<PrintBackend> {
  public:
-  virtual ~PrintBackend();
-
   // Enumerates the list of installed local and network printers.
   virtual bool EnumeratePrinters(PrinterList* printer_list) = 0;
 
@@ -78,6 +76,10 @@ class PRINTING_EXPORT PrintBackend
   // Return NULL if no print backend available.
   static scoped_refptr<PrintBackend> CreateInstance(
       const base::DictionaryValue* print_backend_settings);
+
+ protected:
+  friend class base::RefCountedThreadSafe<PrintBackend>;
+  virtual ~PrintBackend();
 };
 
 }  // namespace printing
diff --git a/printing/backend/print_backend_chromeos.cc b/printing/backend/print_backend_chromeos.cc
index 767251c..003b0fd 100644
--- a/printing/backend/print_backend_chromeos.cc
+++ b/printing/backend/print_backend_chromeos.cc
@@ -12,21 +12,19 @@ namespace printing {
 class PrintBackendChromeOS : public PrintBackend {
  public:
   PrintBackendChromeOS();
-  virtual ~PrintBackendChromeOS() {}
 
   // PrintBackend implementation.
-  virtual bool EnumeratePrinters(PrinterList* printer_list);
-
-  virtual std::string GetDefaultPrinterName();
-
-  virtual bool GetPrinterCapsAndDefaults(const std::string& printer_name,
-                                         PrinterCapsAndDefaults* printer_info);
-
-  virtual std::string GetPrinterDriverInfo(const std::string& printer_name);
-
-  virtual bool IsValidPrinter(const std::string& printer_name);
-
- private:
+  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 ~PrintBackendChromeOS() {}
 };
 
 PrintBackendChromeOS::PrintBackendChromeOS() {}
diff --git a/printing/backend/print_backend_cups.cc b/printing/backend/print_backend_cups.cc
index ae0c553..9bba09a 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
diff --git a/printing/backend/print_backend_win.cc b/printing/backend/print_backend_win.cc
index ae178c7..8dca223 100644
--- a/printing/backend/print_backend_win.cc
+++ b/printing/backend/print_backend_win.cc
@@ -38,18 +38,19 @@ namespace printing {
 class PrintBackendWin : public PrintBackend {
  public:
   PrintBackendWin() {}
-  virtual ~PrintBackendWin() {}
-
-  virtual bool EnumeratePrinters(PrinterList* printer_list);
-
-  virtual std::string GetDefaultPrinterName();
 
-  virtual bool GetPrinterCapsAndDefaults(const std::string& printer_name,
-                                         PrinterCapsAndDefaults* printer_info);
-
-  virtual std::string GetPrinterDriverInfo(const std::string& printer_name);
-
-  virtual bool IsValidPrinter(const std::string& printer_name);
+  // 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 ~PrintBackendWin() {}
 };
 
 bool PrintBackendWin::EnumeratePrinters(PrinterList* printer_list) {