Replace OVERRIDE with its C++11 counterparts in src/printing

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 ba8fe7341695cd517f9de0fbc3e4d446497bfe41..e672b895944b53480eca91a9d23e682f739bddce 100644
--- a/printing/backend/print_backend_cups.cc
+++ b/printing/backend/print_backend_cups.cc
@@ -34,17 +34,17 @@ class PrintBackendCUPS : public PrintBackend {
                    http_encryption_t encryption, bool blocking);
 
   // PrintBackend implementation.
-  virtual bool EnumeratePrinters(PrinterList* printer_list) OVERRIDE;
-  virtual std::string GetDefaultPrinterName() OVERRIDE;
+  virtual bool EnumeratePrinters(PrinterList* printer_list) override;
+  virtual std::string GetDefaultPrinterName() override;
   virtual bool GetPrinterSemanticCapsAndDefaults(
       const std::string& printer_name,
-      PrinterSemanticCapsAndDefaults* printer_info) OVERRIDE;
+      PrinterSemanticCapsAndDefaults* printer_info) override;
   virtual bool GetPrinterCapsAndDefaults(
       const std::string& printer_name,
-      PrinterCapsAndDefaults* printer_info) OVERRIDE;
+      PrinterCapsAndDefaults* printer_info) override;
   virtual std::string GetPrinterDriverInfo(
-      const std::string& printer_name) OVERRIDE;
-  virtual bool IsValidPrinter(const std::string& printer_name) OVERRIDE;
+      const std::string& printer_name) override;
+  virtual bool IsValidPrinter(const std::string& printer_name) override;
 
  protected:
   virtual ~PrintBackendCUPS() {}