Improve license header to match presubmit check

Change-Id: I2c9cdc7386989e6762a5ae1ac00a868235ed8b8c
Reviewed-on: https://chromium-review.googlesource.com/1142407Reviewed-by: Ted Choc <tedchoc@chromium.org>
Commit-Queue: Marcin Wiącek <marcin@mwiacek.com>
Cr-Commit-Position: refs/heads/master@{#576232}

chrome/android/javatests/src/org/chromium/chrome/browser/locale/DefaultSearchEnginePromoDialogTest.java

+// Copyright 2018 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.