extensions/browser/file_reader.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef EXTENSIONS_BROWSER_FILE_READER_H_
   6 #define EXTENSIONS_BROWSER_FILE_READER_H_
   7
   8 #include <string>
   9
  10 #include "base/callback.h"
  11 #include "base/memory/ref_counted.h"
  12 #include "extensions/common/extension_resource.h"
  13
  14 namespace base {
  15 class MessageLoop;
  16 }
  17
  18 // This file defines an interface for reading a file asynchronously on a
  19 // background thread.
  20 // Consider abstracting out a FilePathProvider (ExtensionResource) and moving
  21 // back to chrome/browser/net if other subsystems want to use it.
  22 class FileReader : public base::RefCountedThreadSafe<FileReader> {
  23  public:
  24   // Reports success or failure and the data of the file upon success.
  25   typedef base::Callback<void(bool, const std::string&)> Callback;
  26
  27   FileReader(const extensions::ExtensionResource& resource,
  28              const Callback& callback);
  29
  30   // Called to start reading the file on a background thread.  Upon completion,
  31   // the callback will be notified of the results.
  32   void Start();
  33
  34  private:
  35   friend class base::RefCountedThreadSafe<FileReader>;
  36
  37   virtual ~FileReader();
  38
  39   void ReadFileOnBackgroundThread();
  40
  41   extensions::ExtensionResource resource_;
  42   Callback callback_;
  43   base::MessageLoop* origin_loop_;
  44 };
  45
  46 #endif  // EXTENSIONS_BROWSER_FILE_READER_H_