Clipboard: Update links and comments

Update some now-obsolete links and update comment style

Change-Id: Ie98f57284c21c2a420c8c11d33d140df5fbfee8b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1576220
Auto-Submit: Darwin Huang <huangdarwin@chromium.org>
Commit-Queue: Victor Costan <pwnall@chromium.org>
Reviewed-by: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652761}
6 files changed