arc: Use the MIME type returned by the container to handle content URLs

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

 // 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.
 
 #include "chrome/browser/chromeos/arc/fileapi/arc_content_file_system_url_util.h"
 
 #include "base/files/file_path.h"
 #include "chrome/browser/chromeos/fileapi/external_file_url_util.h"
 #include "net/base/escape.h"
 #include "storage/browser/fileapi/file_system_url.h"
@@ skipping 29 matching lines @@
       chromeos::ExternalFileURLToVirtualPath(external_file_url);
   base::FilePath path_after_root;
   if (!base::FilePath::FromUTF8Unsafe(kContentFileSystemMountPointName)
            .AppendRelativePath(virtual_path, &path_after_root)) {
     return GURL();
   }
   return UnescapeArcUrl(path_after_root.AsUTF8Unsafe());
 }
 
 GURL FileSystemUrlToArcUrl(const storage::FileSystemURL& url) {
+  return PathToArcUrl(url.path());
+}
+
+GURL PathToArcUrl(const base::FilePath& path) {
   base::FilePath path_after_mount_point;
   if (!base::FilePath(kContentFileSystemMountPointPath)
-           .AppendRelativePath(url.path(), &path_after_mount_point)) {
+           .AppendRelativePath(path, &path_after_mount_point)) {
     return GURL();
   }
   return UnescapeArcUrl(path_after_mount_point.AsUTF8Unsafe());
 }
 
 }  // namespace arc