GitLab

Removed unused versioning support in ClipboardInternal. This allowed for
multiple ClipboardData items on a clipboard stack, but the stack size
was limited to 1, and no logic existed to exercise use of any stack
items except the top item on the stack. Therefore, this essentially
amounted to extra logic that wasn't actually needed or used.

Versioning support has been available since at least 2012, when
https://crrev.com/10829341 first introduced this file as a "sketch of
a clipboard implementation for linux_aura".

Change-Id: I7615a97bdd4ef038b0684c75536d2417d746bffe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2309549
Commit-Queue: Victor Costan <pwnall@chromium.org>
Reviewed-by: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#790406}