Change getExtensionPrinters to cr.sendWithPromise

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

 // 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.
 
 #ifndef CHROME_BROWSER_UI_WEBUI_PRINT_PREVIEW_PRINT_PREVIEW_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_PRINT_PREVIEW_PRINT_PREVIEW_HANDLER_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 302 matching lines @@
       const cloud_print::DeviceDescription& description,
       bool has_local_printing,
       base::DictionaryValue* printer_value);
 #endif
 
   // Lazily creates |extension_printer_handler_| that can be used to handle
   // extension printers requests.
   void EnsureExtensionPrinterHandlerSet();
 
   // Called when a list of printers is reported by an extension.
+  // |callback_id|: The javascript callback to call if all extension printers
+  //     are loaded (when |done| = true)
   // |printers|: The list of printers managed by the extension.
   // |done|: Whether all the extensions have reported the list of printers
   //     they manage.
-  void OnGotPrintersForExtension(const base::ListValue& printers, bool done);
+  void OnGotPrintersForExtension(const std::string& callback_id,
+                                 const base::ListValue& printers,
+                                 bool done);
 
   // Called when an extension reports information requested for a provisional
   // printer.
   // |printer_id|: The provisional printer id.
   // |printer_info|: The data reported by the extension.
   void OnGotExtensionPrinterInfo(const std::string& printer_id,
                                  const base::DictionaryValue& printer_info);
 
   // Called when an extension reports the set of print capabilites for a
   // printer.
@@ skipping 65 matching lines @@
   // Proxy for calls to the print backend.  Lazily initialized since web_ui() is
   // not available at construction time.
   std::unique_ptr<printing::PrinterBackendProxy> printer_backend_proxy_;
 
   base::WeakPtrFactory<PrintPreviewHandler> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PrintPreviewHandler);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_PRINT_PREVIEW_PRINT_PREVIEW_HANDLER_H_