Mount MTP devices in Chrome OS Files.app.

chrome/browser/chromeos/fileapi/mtp_file_system_backend_delegate.cc

+// Copyright 2014 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.
+
+#include "chrome/browser/chromeos/fileapi/mtp_file_system_backend_delegate.h"
+#include "chrome/browser/media_galleries/fileapi/device_media_async_file_util.h"
+#include "webkit/browser/blob/file_stream_reader.h"
+#include "webkit/browser/fileapi/file_stream_writer.h"
+
+namespace chromeos {
+
+MTPFileSystemBackendDelegate::MTPFileSystemBackendDelegate(
+    const base::FilePath& storage_partition_path)
+    : device_media_async_file_util_(
+          DeviceMediaAsyncFileUtil::Create(storage_partition_path)) {
+}
+
+MTPFileSystemBackendDelegate::~MTPFileSystemBackendDelegate() {
+}
+
+fileapi::AsyncFileUtil* MTPFileSystemBackendDelegate::GetAsyncFileUtil(
+    fileapi::FileSystemType type) {
+  return device_media_async_file_util_.get();

[mtomasz, 2014/04/24 01:41:42]

nit: How about a DCHECK for a type as in
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/chr...

[kinaba, 2014/04/24 01:52:34]

Done.

+}
+
+scoped_ptr<webkit_blob::FileStreamReader>
+MTPFileSystemBackendDelegate::CreateFileStreamReader(
+    const fileapi::FileSystemURL& url,
+    int64 offset,
+    const base::Time& expected_modification_time,
+    fileapi::FileSystemContext* context) {
+  // TODO(kinaba): Returned MediaFileStreamReader verifies file header and
+  // stops reading if the stream does not represent a media file. We might
+  // want to remove the verification here since we want to mount MTP devices
+  // as normal file storage in Chrome OS file manager.
+  return device_media_async_file_util_->GetFileStreamReader(
+      url, offset, expected_modification_time, context);
+}
+
+scoped_ptr<fileapi::FileStreamWriter>
+MTPFileSystemBackendDelegate::CreateFileStreamWriter(
+    const fileapi::FileSystemURL& url,
+    int64 offset,
+    fileapi::FileSystemContext* context) {
+  // TODO(kinaba): support writing.
+  return scoped_ptr<fileapi::FileStreamWriter>();
+}
+
+}  // namespace chromeos