Remove use of deprecated base::ListValue::Append(Value*) overload in extensions.

chrome/browser/extensions/api/downloads/downloads_api.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_EXTENSIONS_API_DOWNLOADS_DOWNLOADS_API_H_
 #define CHROME_BROWSER_EXTENSIONS_API_DOWNLOADS_DOWNLOADS_API_H_
 
+#include <memory>
 #include <set>
 #include <string>
 
 #include "base/files/file_path.h"
 #include "base/macros.h"
 #include "base/scoped_observer.h"
 #include "base/time/time.h"
 #include "chrome/browser/download/all_download_item_notifier.h"
 #include "chrome/browser/download/download_danger_prompt.h"
 #include "chrome/browser/download/download_path_reservation_tracker.h"
@@ skipping 363 matching lines @@
   };
 
   void CheckForHistoryFilesRemoval();
 
  private:
   void DispatchEvent(
       events::HistogramValue histogram_value,
       const std::string& event_name,
       bool include_incognito,
       const extensions::Event::WillDispatchCallback& will_dispatch_callback,
-      base::Value* json_arg);
+      std::unique_ptr<base::Value> json_arg);
 
   // extensions::ExtensionRegistryObserver.
   void OnExtensionUnloaded(
       content::BrowserContext* browser_context,
       const extensions::Extension* extension,
       extensions::UnloadedExtensionInfo::Reason reason) override;
 
   Profile* profile_;
   AllDownloadItemNotifier notifier_;
   std::set<const extensions::Extension*> shelf_disabling_extensions_;
 
   base::Time last_checked_removal_;
 
   // Listen to extension unloaded notifications.
   ScopedObserver<extensions::ExtensionRegistry,
                  extensions::ExtensionRegistryObserver>
       extension_registry_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionDownloadsEventRouter);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_DOWNLOADS_DOWNLOADS_API_H_