WebUI Dark Mode: update "drop to install" dialog on extensions page

Screenshot: on bug

R=rdevlin.cronin@chromium.org
BUG=937165

Change-Id: If381e0cf96b9649fc5c3871cf6a7887e8176c9f3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1496598
Auto-Submit: Dan Beam <dbeam@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#637500}
1 file changed