Normalize copyright headers in chrome_cleaner

Global search and replace of "Copyright (c) 2018" with "Copyright 2018"
to match the style guide.

R=csharp

Bug: 830892
Change-Id: I9db77f6b26b7639499b82690360b26805588d304
Reviewed-on: https://chromium-review.googlesource.com/1195718
Reviewed-by: Chris Sharp <csharp@chromium.org>
Commit-Queue: Joe Mason <joenotcharles@chromium.org>
Cr-Commit-Position: refs/heads/master@{#587641}
39 files changed