Relegate michaelpg to CrOS webui changes

Bug: none
Change-Id: I985c149e396912fd65bf0e7ce3ac6710ae8dadb5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2351140
Auto-Submit: Michael Giuffrida <michaelpg@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Commit-Queue: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#797113}

ui/webui/PLATFORM_OWNERS

@@ -5,6 +5,6 @@ calamity@chromium.org
 dpapad@chromium.org
 dschuyler@chromium.org
 khorimoto@chromium.org  # For Chrome OS changes.
-michaelpg@chromium.org
+michaelpg@chromium.org  # For Chrome OS changes.
 rbpotter@chromium.org
 tommycli@chromium.org