Enable the cups backend when --enable-native-cups is specified.

printing/backend/print_backend_chromeos.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "printing/backend/print_backend.h"
 
 #include "base/logging.h"
+#include "base/values.h"
+#include "printing/backend/print_backend_consts.h"
+#include "url/gurl.h"
+
+#if defined(USE_CUPS)
+#include "printing/backend/print_backend_cups.h"
+#endif  // defined(USE_CUPS)
 
 namespace printing {
 
 // Provides a stubbed out PrintBackend implementation for use on ChromeOS.
 class PrintBackendChromeOS : public PrintBackend {
  public:
   PrintBackendChromeOS();
 
   // PrintBackend implementation.
   bool EnumeratePrinters(PrinterList* printer_list) override;
@@ skipping 47 matching lines @@
   return std::string();
 }
 
 bool PrintBackendChromeOS::IsValidPrinter(const std::string& printer_name) {
   NOTREACHED();
   return true;
 }
 
 scoped_refptr<PrintBackend> PrintBackend::CreateInstance(
     const base::DictionaryValue* print_backend_settings) {
+  if (GetNativeCupsEnabled()) {
+#if defined(USE_CUPS)
+    std::string print_server_url_str;
+    std::string cups_blocking;
+    int encryption = HTTP_ENCRYPT_NEVER;
+    if (print_backend_settings) {
+      print_backend_settings->GetString(kCUPSPrintServerURL,
+                                        &print_server_url_str);
+
+      print_backend_settings->GetString(kCUPSBlocking, &cups_blocking);
+
+      print_backend_settings->GetInteger(kCUPSEncryption, &encryption);
+    }
+    GURL print_server_url(print_server_url_str.c_str());
+    return new PrintBackendCUPS(print_server_url,
+                                static_cast<http_encryption_t>(encryption),
+                                cups_blocking == kValueTrue);
+#endif  // defined(USE_CUPS)
+  }
+
   return new PrintBackendChromeOS();
 }
 
 }  // namespace printing
-