Present the printer list from preferences for Chrome OS.

chrome/browser/ui/webui/print_preview/printer_backend_proxy.h

Index: chrome/browser/ui/webui/print_preview/printer_backend_proxy.h
diff --git a/chrome/browser/ui/webui/print_preview/printer_backend_proxy.h b/chrome/browser/ui/webui/print_preview/printer_backend_proxy.h
new file mode 100644
index 0000000000000000000000000000000000000000..33173a8d165acdae8e6718f592cfa3ed10bf662c
--- /dev/null
+++ b/chrome/browser/ui/webui/print_preview/printer_backend_proxy.h
@@ -0,0 +1,30 @@
+// 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.
+
+#ifndef CHROME_BROWSER_UI_WEBUI_PRINT_PREVIEW_PRINTER_BACKEND_PROXY_H_
+#define CHROME_BROWSER_UI_WEBUI_PRINT_PREVIEW_PRINTER_BACKEND_PROXY_H_
+
+#include <memory>
+#include <string>
+
+#include "base/callback_forward.h"
+#include "base/values.h"
+#include "printing/backend/print_backend.h"
+
+class Profile;
+
+namespace printing {
+
+using EnumeratePrintersCallback = base::Callback<void(const PrinterList&)>;
+
+// Returns the name of the default printer.
+std::string GetDefaultPrinterOnBlockingPoolThread();
+
+// Retrieves printers for display in the print dialog and calls |cb| with the
+// list.

[Lei Zhang, 2016/11/04 21:46:51]

Mention this must be called on the UI thread.

[skau, 2016/11/04 22:31:16]

Done.

+void EnumeratePrinters(Profile* profile, const EnumeratePrintersCallback& cb);
+
+}  // namespace printing
+
+#endif  // CHROME_BROWSER_UI_WEBUI_PRINT_PREVIEW_PRINTER_BACKEND_PROXY_H_