Add FileReader interface and implement FileSystemFileReader

webkit/fileapi/file_system_file_reader.h

Index: webkit/fileapi/file_system_file_reader.h
diff --git a/webkit/fileapi/file_system_file_reader.h b/webkit/fileapi/file_system_file_reader.h
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+++ b/webkit/fileapi/file_system_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_FILEAPI_FILE_SYSTEM_FILE_READER_H_
+#define WEBKIT_FILEAPI_FILE_SYSTEM_FILE_READER_H_
+#pragma once
+
+#include "base/bind.h"
+#include "base/memory/ref_counted.h"
+#include "base/platform_file.h"
+#include "googleurl/src/gurl.h"
+#include "webkit/blob/file_reader.h"
+
+class FilePath;
+
+namespace base {
+class MessageLoopProxy;
+}
+
+namespace webkit_blob {
+class LocalFileReader;
+class ShareableFileReference;
+}
+
+namespace fileapi {
+
+class FileSystemContext;
+
+// TODO(kinaba,satorux): This generic implementation would work for any
+// filesystems but remote filesystem should implement its own reader
+// rather than relying on FileSystemOperation::GetSnapshotFile() which
+// may force downloading the entire contents for remote files.
+class FileSystemFileReader : public webkit_blob::FileReader {
+ public:
+  // Creates a new FileReader for a filesystem URL |url| form |initial_offset|.
+  FileSystemFileReader(base::MessageLoopProxy* file_thread_proxy,
+                       FileSystemContext* file_system_context,
+                       const GURL& url,
+                       int64 initial_offset);
+  virtual ~FileSystemFileReader();
+
+  // FileReader override.
+  virtual int Read(net::IOBuffer* buf, int buf_len,
+                   const net::CompletionCallback& callback) OVERRIDE;
+
+ private:
+  void DidCreateSnapshot(
+      const base::Closure& read_closure,
+      const net::CompletionCallback& callback,
+      base::PlatformFileError file_error,
+      const base::PlatformFileInfo& file_info,
+      const FilePath& platform_path,
+      const scoped_refptr<webkit_blob::ShareableFileReference>& file_ref);
+
+  scoped_refptr<base::MessageLoopProxy> file_thread_proxy_;
+  scoped_refptr<FileSystemContext> file_system_context_;
+  const GURL url_;
+  const int64 initial_offset_;
+  scoped_ptr<webkit_blob::LocalFileReader> local_file_reader_;
+  scoped_refptr<webkit_blob::ShareableFileReference> snapshot_ref_;
+  bool has_pending_create_snapshot_;
+  base::WeakPtrFactory<FileSystemFileReader> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(FileSystemFileReader);
+};
+
+}  // namespace fileapi
+
+#endif  // WEBKIT_FILEAPI_FILE_SYSTEM_FILE_READER_H_