Present the printer list from preferences for Chrome OS.

chrome/browser/ui/webui/print_preview/printer_backend_proxy.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 "chrome/browser/ui/webui/print_preview/printer_backend_proxy.h"
+
+#include <string>
+
+#include "base/logging.h"
+#include "base/memory/ref_counted.h"
+#include "content/public/browser/browser_thread.h"
+#include "printing/backend/print_backend.h"
+
+namespace printing {
+
+namespace {
+
+PrinterList EnumeratePrintersOnBlockingPoolThread() {
+  DCHECK(content::BrowserThread::GetBlockingPool()->RunsTasksOnCurrentThread());
+
+  scoped_refptr<PrintBackend> print_backend(
+      PrintBackend::CreateInstance(nullptr));
+
+  PrinterList printer_list;
+  print_backend->EnumeratePrinters(&printer_list);
+
+  return printer_list;
+}
+
+}  // namespace
+
+std::string GetDefaultPrinterOnBlockingPoolThread() {
+  DCHECK(content::BrowserThread::GetBlockingPool()->RunsTasksOnCurrentThread());
+
+  scoped_refptr<printing::PrintBackend> print_backend(
+      PrintBackend::CreateInstance(nullptr));
+
+  std::string default_printer = print_backend->GetDefaultPrinterName();
+  VLOG(1) << "Default Printer: " << default_printer;
+  return default_printer;
+}
+
+void EnumeratePrinters(Profile* /* profile */,
+                       const EnumeratePrintersCallback& cb) {
+  base::PostTaskAndReplyWithResult(
+      content::BrowserThread::GetBlockingPool(), FROM_HERE,
+      base::Bind(&EnumeratePrintersOnBlockingPoolThread), cb);
+}
+
+}  // namespace printing