Fix various issues in RedirectToFileResourceHandler.

content/browser/loader/temporary_file_stream.h

+// Copyright 2013 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 CONTENT_BROWSER_LOADER_TEMPORARY_FILE_STREAM_H_
+#define CONTENT_BROWSER_LOADER_TEMPORARY_FILE_STREAM_H_
+
+#include "base/callback_forward.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/platform_file.h"
+#include "content/common/content_export.h"
+
+namespace net {
+class FileStream;
+}
+
+namespace webkit_blob {
+class ShareableFileReference;
+}
+
+namespace content {
+
+typedef base::Callback<void(base::PlatformFileError,
+                            scoped_ptr<net::FileStream>,
+                            webkit_blob::ShareableFileReference*)>
+    CreateTemporaryFileStreamCallback;
+
+// Creates a temporary file and asynchronously calls |callback| with a
+// net::FileStream and webkit_blob::ShareableFileReference The file is deleted

[mmenke, 2014/01/16 16:43:26]

nit:  period after webkit_blob::ShareableFileReference

[davidben, 2014/01/29 21:41:50]

Done.

+// when the webkit_blob::ShareableFileReference is deleted. Note it is the
+// consumer's responsibility to ensure the webkit_blob::ShareableFileReference
+// stays in scope until net::FileStream has finished closing the file. On error,
+// |callback| is called with an error in the first parameter.

[mmenke, 2014/01/16 16:43:26]

I don't think it's obvious that this method is not threadsafe
(ShareableFileReference::GetOrCreate isn't threadsafe).  Suggest a comment and
DCHECKing that we're called on the IO thread.

[davidben, 2014/01/29 21:41:50]

Done.

+//
+// TODO(davidben): Juggling the net::FileStream and
+// webkit_blob::ShareableFileReference lifetimes is a nuisance. The two should
+// be tied together so the consumer need not deal with it.
+CONTENT_EXPORT void CreateTemporaryFileStream(
+    const CreateTemporaryFileStreamCallback& callback);
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_LOADER_TEMPORARY_FILE_STREAM_H_