Fix toast font color

Bug: 1145890
Change-Id: I6c8cc8b063640dd4bcb4b388515bc391cee68966
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2521046


Reviewed-by: Theresa <twellington@chromium.org>
Commit-Queue: Gayane Petrosyan <gayane@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824558}