{kCopiedStub} is not used any more since https://crrev.com/c/1012024.

R=mstarzinger@chromium.org

Change-Id: Idb0049f7d0bb0215cef902daba49591596f93668
Reviewed-on: https://chromium-review.googlesource.com/1042225Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52956}