Apply missing kParentDirectory check

BUG=161564

Review URL: https://chromiumcodereview.appspot.com/11414046

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@168692 0039d316-1c4b-4281-b951-d872f2087c98
  void GrantPermissionsForFileSystem(const std::string& filesystem_id,
                                     int permissions) {
    if (filesystem_permissions_.find(filesystem_id) ==
        filesystem_permissions_.end())
      fileapi::IsolatedContext::GetInstance()->AddReference(filesystem_id);
    filesystem_permissions_[filesystem_id] = permissions;
  }

  void GrantPermissionsForFileSystem(const std::string& filesystem_id,
                                     int permissions) {
    if (filesystem_permissions_.find(filesystem_id) ==
        filesystem_permissions_.end())
      fileapi::IsolatedContext::GetInstance()->AddReference(filesystem_id);
    filesystem_permissions_[filesystem_id] = permissions;
  }
