Register and select printer on click.

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

 // 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 PrinterSetupCallback =
+    base::Callback<void(std::unique_ptr<base::DictionaryValue>)>;
+
 // Returns the name of the default printer.
 std::string GetDefaultPrinterOnBlockingPoolThread();
 
 // Returns printers for display in the print dialog.
 PrinterList EnumeratePrintersOnBlockingPoolThread(Profile* profile);
 
+// Verifies printer setup then retrieves printer capabilities for

[Lei Zhang, 2016/11/03 23:41:46]

Maybe say "Verifies printer setup if needed ..." since on non-ChromeOS, there's
no set up happening.

[skau, 2016/11/04 19:28:59]

Done.

+// |printer_name|.  |cb| is called with the capabilities dictionary or nullptr
+// if one of the steps failed.
+void ConfigurePrinterAndFetchCapabilities(Profile* profile,
+                                          const std::string& printer_name,
+                                          const PrinterSetupCallback& cb);
+
 }  // namespace printing
 
 #endif  // CHROME_BROWSER_UI_WEBUI_PRINT_PREVIEW_PRINTER_BACKEND_PROXY_H_