Reset null dialog icons

Presently, we call .mutate() on a potentially null icon. In
these cases, we should instead clear the icon.

Bug: 966909
Change-Id: I6181c72d29ef15dfd543affcd7b8b38a664eef95
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1676724
Reviewed-by: Michael Thiessen <mthiesse@chromium.org>
Commit-Queue: Ian Vollick <vollick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672142}
1 file changed