Don't use deprecated ListValue::Append(Value*) overload.

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 <stddef.h>
 
 #include <map>
@@ skipping 400 matching lines @@
   DCHECK(BrowserThread::GetBlockingPool()->RunsTasksOnCurrentThread());
 
   scoped_refptr<printing::PrintBackend> print_backend(
       printing::PrintBackend::CreateInstance(nullptr));
 
   VLOG(1) << "Enumerate printers start";
   printing::PrinterList printer_list;
   print_backend->EnumeratePrinters(&printer_list);
 
   for (const printing::PrinterBasicInfo& printer : printer_list) {
-    base::DictionaryValue* printer_info = new base::DictionaryValue;
-    printers->Append(printer_info);
-
+    std::unique_ptr<base::DictionaryValue> printer_info(
+        new base::DictionaryValue);
     const auto printer_name_description = GetPrinterNameAndDescription(printer);
     const std::string& printer_name = printer_name_description.first;
     const std::string& printer_description = printer_name_description.second;
     printer_info->SetString(printing::kSettingDeviceName, printer.printer_name);
     printer_info->SetString(printing::kSettingPrinterName, printer_name);
     printer_info->SetString(printing::kSettingPrinterDescription,
                             printer_description);
 
     base::DictionaryValue* options = new base::DictionaryValue;
     printer_info->Set(printing::kSettingPrinterOptions, options);
     for (const auto opt_it : printer.options)
       options->SetString(opt_it.first, opt_it.second);
 
+    printers->Append(std::move(printer_info));
+
     VLOG(1) << "Found printer " << printer_name << " with device name "
             << printer.printer_name;
   }
   VLOG(1) << "Enumerate printers finished, found " << printers->GetSize()
           << " printers";
 }
 
 std::unique_ptr<base::DictionaryValue>
 GetPrinterCapabilitiesOnBlockingPoolThread(const std::string& device_name) {
   DCHECK(BrowserThread::GetBlockingPool()->RunsTasksOnCurrentThread());
@@ skipping 1346 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;
 }