arc: Add URL converter functions

chrome/browser/chromeos/arc/fileapi/arc_content_file_system_url_util.h

+// Copyright 2016 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 CHROME_BROWSER_CHROMEOS_ARC_FILEAPI_ARC_CONTENT_FILE_SYSTEM_URL_UTIL_H_
+#define CHROME_BROWSER_CHROMEOS_ARC_FILEAPI_ARC_CONTENT_FILE_SYSTEM_URL_UTIL_H_
+
+#include "url/gurl.h"
+
+namespace arc {
+
+// Converts a URL which can be used within the ARC container to an externalfile:
+// URL which can be used by Chrome.
+GURL ArcUrlToExternalFileUrl(const GURL& arc_url);
+
+// Converts an externalfile: URL to a URL which can be used within the ARC
+// container. If the given URL cannot be converted to an ARC URL, returns an
+// empty GURL.
+GURL ExternalFileUrlToArcUrl(const GURL& external_file_url);
+
+}  // namespace arc
+
+#endif  // CHROME_BROWSER_CHROMEOS_ARC_FILEAPI_ARC_CONTENT_FILE_SYSTEM_URL_UTIL_H_