Update ui/webui/PLATFORM_OWNERS.

Removing two entries of developers who have moved on to non-WebUI
primary responsibilities.

Fixed: 1055481
Change-Id: Iac803a00aeda0da8bf6f49d4d94882846f3ad643
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2528175Reviewed-by: Tommy Li <tommycli@chromium.org>
Reviewed-by: Esmael Elmoslimany <aee@chromium.org>
Commit-Queue: Esmael Elmoslimany <aee@chromium.org>
Auto-Submit: dpapad <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825934}

ui/webui/PLATFORM_OWNERS

@@ -3,9 +3,7 @@ aee@chromium.org
 antrim@chromium.org  # CET
 calamity@chromium.org
 dpapad@chromium.org
-dschuyler@chromium.org
 johntlee@chromium.org
 khorimoto@chromium.org  # For Chrome OS changes.
 michaelpg@chromium.org  # For Chrome OS changes.
 rbpotter@chromium.org
-tommycli@chromium.org