[fsp] Add FileStreamReader for the reading operation.

chrome/browser/chromeos/fileapi/file_system_backend.cc

 // 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.
 
 #include "chrome/browser/chromeos/fileapi/file_system_backend.h"
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/stringprintf.h"
 #include "chrome/browser/chromeos/fileapi/file_access_permissions.h"
@@ skipping 259 matching lines @@
          url.type() == fileapi::kFileSystemTypeRestrictedNativeLocal ||
          url.type() == fileapi::kFileSystemTypeDrive ||
          url.type() == fileapi::kFileSystemTypeProvided);
   return fileapi::FileSystemOperation::Create(
       url, context,
       make_scoped_ptr(new fileapi::FileSystemOperationContext(context)));
 }
 
 bool FileSystemBackend::SupportsStreaming(
     const fileapi::FileSystemURL& url) const {
-  return url.type() == fileapi::kFileSystemTypeDrive;
+  return url.type() == fileapi::kFileSystemTypeDrive ||
+         url.type() == fileapi::kFileSystemTypeProvided;
 }
 
 scoped_ptr<webkit_blob::FileStreamReader>
 FileSystemBackend::CreateFileStreamReader(
     const fileapi::FileSystemURL& url,
     int64 offset,
     const base::Time& expected_modification_time,
     fileapi::FileSystemContext* context) const {
   DCHECK(url.is_valid());
 
@@ skipping 54 matching lines @@
 }
 
 bool FileSystemBackend::GetVirtualPath(
     const base::FilePath& filesystem_path,
     base::FilePath* virtual_path) {
   return mount_points_->GetVirtualPath(filesystem_path, virtual_path) ||
          system_mount_points_->GetVirtualPath(filesystem_path, virtual_path);
 }
 
 }  // namespace chromeos