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diff --git a/webkit/blob/local_file_reader.h b/webkit/blob/local_file_reader.h
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+// 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 WEBKIT_BLOB_LOCAL_FILE_READER_H_
+#define WEBKIT_BLOB_LOCAL_FILE_READER_H_
+#pragma once
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/file_path.h"
+#include "base/memory/weak_ptr.h"
+#include "base/time.h"
+#include "net/base/completion_callback.h"
+#include "webkit/blob/blob_export.h"
+
+namespace base {
+class MessageLoopProxy;
+}
+
+namespace net {
+class FileStream;
+class IOBuffer;
+}
+
+namespace webkit_blob {
+
+// A thin wrapper of net::FileStream with range support for sliced file
+// handling.
+class BLOB_EXPORT LocalFileReader {
+ public:
+  typedef base::Callback<void(int error, scoped_ptr<net::FileStream> stream)>
+      OpenFileStreamCallback;
+
+  // Creates a new FileReader for a local file |file_path|.
+  // |initial_offset| specifies the offset in the file where the first read
+  // should start.
+  // |expected_modification_time| specifies the expected last modification
+  // If the value is non-null, the reader will check the underlying file's
+  // actual modification time to see if the file has been modified, and if
+  // it does any succeeding read operations should fail with
+  // ERR_UPLOAD_FILE_CHANGED error.
+  LocalFileReader(base::MessageLoopProxy* file_thread_proxy,
+                  const FilePath& file_path,
+                  int64 initial_offset,
+                  const base::Time& expected_modification_time);
+
+  ~LocalFileReader();
+
+  // Reads from the current cursor position asynchronously.
+  // This works mostly same as how net::FileStream::Read() works except that
+  // it internally opens (and seeks) the file if it is not opened yet.
+  // It is invalid to call Read while there is an in-flight Read operation.
+  int Read(net::IOBuffer* buf, int buf_len,
+           const net::CompletionCallback& callback);
+
+  // Returns the number of bytes available to read from the beginning of
+  // the file (or initial_offset) until the end of the file (rv >= 0 cases).
+  // Otherwise, a negative error code is returned (rv < 0 cases).
+  int GetLength(const net::CompletionCallback& callback);
+
+ private:
+  class OpenFileStreamHelper;
+
+  int Open(const OpenFileStreamCallback& callback);
+  void DidOpen(net::IOBuffer* buf,
+               int buf_len,
+               const net::CompletionCallback& callback,
+               int open_error,
+               scoped_ptr<net::FileStream> stream);
+
+  scoped_refptr<base::MessageLoopProxy> file_thread_proxy_;
+  scoped_ptr<net::FileStream> stream_impl_;
+  const FilePath file_path_;
+  const int64 initial_offset_;
+  const base::Time expected_modification_time_;
+  bool has_pending_open_;
+  base::WeakPtrFactory<LocalFileReader> weak_factory_;
+};
+
+}  // namespace webkit_blob
+
+#endif  // WEBKIT_BLOB_LOCAL_FILE_READER_H_