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

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

 // 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.
 
 #include "chrome/browser/ui/webui/print_preview/print_preview_handler.h"
 
 #include <ctype.h>
 
 #include <map>
 #include <string>
@@ skipping 1665 matching lines @@
   printer_value->SetBoolean(
       "isUnregistered",
       description.id.empty() &&
       command_line->HasSwitch(switches::kEnablePrintPreviewRegisterPromos));
   printer_value->SetString("cloudID", description.id);
 }
 
 #endif  // defined(ENABLE_SERVICE_DISCOVERY)
 
 void PrintPreviewHandler::EnsureExtensionPrinterHandlerSet() {
-  if (extension_printer_handler_.get())
+  if (extension_printer_handler_)
     return;
 
   extension_printer_handler_ =
       PrinterHandler::CreateForExtensionPrinters(Profile::FromWebUI(web_ui()));
 }
 
 void PrintPreviewHandler::OnGotPrintersForExtension(
     const base::ListValue& printers,
     bool done) {
   web_ui()->CallJavascriptFunction("onExtensionPrintersAdded", printers,
@@ skipping 39 matching lines @@
 
 void PrintPreviewHandler::UnregisterForGaiaCookieChanges() {
   if (gaia_cookie_manager_service_)
     gaia_cookie_manager_service_->RemoveObserver(this);
 }
 
 void PrintPreviewHandler::SetPdfSavedClosureForTesting(
     const base::Closure& closure) {
   pdf_file_saved_closure_ = closure;
 }