Add an accessible describedby relation to bubble dialogs.

The JAWS screen reader is not announcing the text of a
bubble dialog when it appears unless the user presses
a hot key to read the whole dialog. This can be mitigated
by adding a "describedby" relation between the dialog and
the main label text.

Bug: 953325
Change-Id: I8f9a68a80d7d7e91ea51f2816a3d85e312e93b39
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1582844
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Reviewed-by: Aaron Leventhal <aleventhal@chromium.org>
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#657371}
4 files changed