GitLab

This CL adds a SharesheetParentWidgetObserver which
observes changes in the parent widget and updates the
position of the bubble to remain anchored to it.

Bug: 1159674
Change-Id: I9bc7d180b249fda54bc387b83501063be72ab37f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2596899Reviewed-by: Dominick Ng <dominickn@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Melissa Zhang <melzhang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#840469}