GitLab

Add functionality for reordering custom links. Will initialize if
custom links has not been initialized yet.

Bug: 851335
Change-Id: I67710b4187f8f5a45d7f96814c17294f87d60b22
Reviewed-on: https://chromium-review.googlesource.com/c/1308899
Commit-Queue: Kristi Park <kristipark@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604419}