Fix a small leak in FileUtilProxy

BUG=none
TEST=green mem bots

Review URL: http://codereview.chromium.org/7669046

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@97451 0039d316-1c4b-4281-b951-d872f2087c98
bool FileUtilProxy::ReadDirectory(
    scoped_refptr<MessageLoopProxy> message_loop_proxy,
    const FilePath& file_path,
    ReadDirectoryCallback* callback) {
  return Start(FROM_HERE, message_loop_proxy, new RelayReadDirectory(
               file_path, callback));
}

bool FileUtilProxy::ReadDirectory(
    scoped_refptr<MessageLoopProxy> message_loop_proxy,
    const FilePath& file_path,
    ReadDirectoryCallback* callback) {
  return Start(FROM_HERE, message_loop_proxy, new RelayReadDirectory(
               file_path, callback));
}
