Add the ability for objects which derive from RefCountedThreadSafe to specify...

chrome/browser/renderer_host/file_system_accessor.h

-// Copyright (c) 2006-2009 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.
-//
-// FileSystemAccessor provides functions so consumers can do file access
-// asynchronously. It would PostTask to FILE thread to access file info, then on
-// completion PostTask back to the caller thread and pass the result back.
-// Here is an example on how to use it to get file size:
-//   1. Define a callback function so FileSystemAccessor could run it after the
-//      task has been completed:
-//      void Foo::GetFileSizeCallback(int64 result, void* param) {
-//      }
-//   2. Call static function FileSystemAccessor::RequestFileSize, provide file
-//      path, param (any object you want to pass back to the callback function)
-//      and callback:
-//      FileSystemAccessor::RequestFileSize(
-//          path,
-//          param,
-//          NewCallback(this, &Foo::GetFileSizeCallback));
-//   3. FileSystemAceessor would PostTask to FILE thread to get file size, then
-//      on completion it would PostTask back to the current thread and run
-//      Foo::GetFileSizeCallback.
-//
-
-#ifndef CHROME_BROWSER_RENDERER_HOST_FILE_SYSTEM_ACCESSOR_H_
-#define CHROME_BROWSER_RENDERER_HOST_FILE_SYSTEM_ACCESSOR_H_
-
-#include "base/scoped_ptr.h"
-#include "base/ref_counted.h"
-#include "base/task.h"
-
-class FilePath;
-class MessageLoop;
-
-class FileSystemAccessor
-    : public base::RefCountedThreadSafe<FileSystemAccessor> {
- public:
-  typedef Callback2<int64, void*>::Type FileSizeCallback;
-
-  virtual ~FileSystemAccessor();
-
-  // Request to get file size.
-  //
-  // param is an object that is owned by the caller and needs to pass back to
-  // the caller by FileSystemAccessor through the callback function.
-  // It can be set to NULL if no object needs to pass back.
-  //
-  // FileSizeCallback function is defined as:
-  // void f(int64 result, void* param);
-  // Variable result has the file size. If the file does not exist or there is
-  // error accessing the file, result is set to -1. If the given path is a
-  // directory, result is set to 0.
-  static void RequestFileSize(const FilePath& path,
-                              void* param,
-                              FileSizeCallback* callback);
-
- private:
-  FileSystemAccessor(void* param, FileSizeCallback* callback);
-
-  // Get file size on the worker thread and pass result back to the caller
-  // thread.
-  void GetFileSize(const FilePath& path);
-
-  // Getting file size completed, callback to reply message.
-  void GetFileSizeCompleted(int64 result);
-
-  MessageLoop* caller_loop_;
-  void* param_;
-  scoped_ptr<FileSizeCallback> callback_;
-
-  DISALLOW_COPY_AND_ASSIGN(FileSystemAccessor);
-};
-
-#endif  // CHROME_BROWSER_RENDERER_HOST_FILE_SYSTEM_ACCESSOR_H_