We no longer use the DISALLOW_COPY_AND_ASSIGN macro.

BUG=angleproject:956

Change-Id: I439c4d55612059d6a16ae6351c54c3817be017cf
Reviewed-on: https://chromium-review.googlesource.com/263480Reviewed-by: Brandon Jones <bajones@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>