GitLab

Adds "Scanning for nearby devices..." in place of the share target
list on the discovery page when the list is empty. Needed because
the only other indication on the screen that something is happening
is the animation, which isn't accessible for screen readers.

Bug: b/163036847
Change-Id: I22cf34025727315bd2a02934fdec7ba179b6b169
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2490661
Commit-Queue: Curt Clemens <cclem@google.com>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Reviewed-by: James Vecore <vecore@google.com>
Cr-Commit-Position: refs/heads/master@{#824105}