Add flackr to platform/widget/input OWNERS.

Bug: None
Change-Id: Id47626c66cd4f1f2ac37cea3c273eebb303b5bfd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2403880Reviewed-by: David Bokan <bokan@chromium.org>
Commit-Queue: Robert Flack <flackr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#806629}

third_party/blink/renderer/platform/widget/input/OWNERS

@@ -2,6 +2,7 @@ dtapuska@chromium.org
 tdresser@chromium.org
 bokan@chromium.org
 nzolghadr@chromium.org
+flackr@chromium.org
 
 # TEAM: input-dev@chromium.org
 # COMPONENT: Blink>Input