Move CrxFile, FileReader, ExtensionResource to src/extensions.

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_
-
-#include <string>
-
-#include "base/callback.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> {
- public:
-  // Reports success or failure and the data of the file upon success.
-  typedef base::Callback<void(bool, const std::string&)> Callback;
-
-  FileReader(const ExtensionResource& resource, const Callback& callback);
-
-  // Called to start reading the file on a background thread.  Upon completion,
-  // the callback will be notified of the results.
-  void Start();
-
- private:
-  friend class base::RefCountedThreadSafe<FileReader>;
-
-  virtual ~FileReader();
-
-  void ReadFileOnBackgroundThread();
-
-  ExtensionResource resource_;
-  Callback callback_;
-  MessageLoop* origin_loop_;
-};
-
-#endif  // CHROME_BROWSER_EXTENSIONS_FILE_READER_H_