Reland 132134 with memory fix - Use LocalFileReader in FileSystemURLRequestJob

webkit/blob/local_file_reader.h

 // 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"
@@ skipping 16 matching lines @@
 
 // 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.
+  // should start.  If the given offset is out of the file range any
+  // read operation may error out with net::ERR_REQUEST_RANGE_NOT_SATISFIABLE.
+  //
   // |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);
 
@@ skipping 26 matching lines @@
   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_