Use printer id to populate CUPS instead of printer name.

chromeos/printing/printer_configuration.cc

 // Copyright 2016 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 "chromeos/printing/printer_configuration.h"
 
 #include <string>
 
+#include "base/guid.h"
+
 namespace chromeos {
 
-Printer::Printer() {}
+Printer::Printer() {
+  id_ = base::GenerateGUID();
+}
 
-Printer::Printer(const std::string& id) : id_(id) {}
+Printer::Printer(const std::string& id) : id_(id) {
+  if (id_.empty())
+    id_ = base::GenerateGUID();
+}
 
 Printer::Printer(const Printer& other) = default;
 
 Printer& Printer::operator=(const Printer& other) = default;
 
 Printer::~Printer() {}
 
 }  // namespace chromeos