Include USB printers in printer list as "provisional" devices.

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

 // Copyright 2015 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_EXTENSION_PRINTER_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_PRINT_PREVIEW_EXTENSION_PRINTER_HANDLER_H_
 
 #include <string>
+#include <vector>
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/strings/string16.h"
 #include "chrome/browser/ui/webui/print_preview/printer_handler.h"
 #include "extensions/browser/api/printer_provider/printer_provider_api.h"
 
 namespace base {
 class DictionaryValue;
 class ListValue;
 class RefCountedMemory;
 class TaskRunner;
 }
 
 namespace content {
 class BrowserContext;
 }
 
 namespace cloud_devices {
 class CloudDeviceDescription;
 }
 
+namespace device {
+class UsbDevice;
+}
+
 namespace gfx {
 class Size;
 }
 
 namespace local_discovery {
 class PWGRasterConverter;
 }
 
 // Implementation of PrinterHandler interface backed by printerProvider
 // extension API.
@@ skipping 44 matching lines @@
   // Sets print job document data and dispatches it using printerProvider API.
   void DispatchPrintJob(
       const PrinterHandler::PrintCallback& callback,
       scoped_ptr<extensions::PrinterProviderPrintJob> print_job);
 
   // Methods used as wrappers to callbacks for extensions::PrinterProviderAPI
   // methods, primarily so the callbacks can be bound to this class' weak ptr.
   // They just propagate results to callbacks passed to them.
   void WrapGetPrintersCallback(
       const PrinterHandler::GetPrintersCallback& callback,
-      const base::ListValue& pritners,
+      const base::ListValue& printers,
       bool done);
   void WrapGetCapabilityCallback(
       const PrinterHandler::GetCapabilityCallback& callback,
       const std::string& destination_id,
       const base::DictionaryValue& capability);
   void WrapPrintCallback(const PrinterHandler::PrintCallback& callback,
                          bool success,
                          const std::string& status);
+  void OnUsbDevicesEnumerated(
+      const PrinterHandler::GetPrintersCallback& callback,
+      const std::vector<scoped_refptr<device::UsbDevice>>& devices);
 
   content::BrowserContext* browser_context_;
 
   scoped_ptr<local_discovery::PWGRasterConverter> pwg_raster_converter_;
+  int pending_enumeration_count_ = 0;
 
   scoped_refptr<base::TaskRunner> slow_task_runner_;
 
   base::WeakPtrFactory<ExtensionPrinterHandler> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionPrinterHandler);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_PRINT_PREVIEW_EXTENSION_PRINTER_HANDLER_H_