iwyu: Use callback_old.h where appropriate, part 2.

chrome/browser/extensions/file_reader.h

 // Copyright (c) 2011 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_FILE_READER_H_
 #define CHROME_BROWSER_EXTENSIONS_FILE_READER_H_
 #pragma once
 
 #include <string>
 
-#include "base/callback.h"
+#include "base/callback_old.h"
 #include "base/memory/ref_counted.h"
 #include "chrome/common/extensions/extension_resource.h"
 
 class MessageLoop;
 
 // This file defines an interface for reading a file asynchronously on a
 // background thread.
 // Consider abstracting out a FilePathProvider (ExtensionResource) and moving
 // back to chrome/browser/net if other subsystems want to use it.
 class FileReader : public base::RefCountedThreadSafe<FileReader> {
@@ skipping 14 matching lines @@
 
   void ReadFileOnBackgroundThread();
   void RunCallback(bool success, const std::string& data);
 
   ExtensionResource resource_;
   Callback* callback_;
   MessageLoop* origin_loop_;
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_FILE_READER_H_