[SendTabToSelf] only include committers as OWNERS

Bug: 910390
Change-Id: I87d9aa4751c6abb53a549ceabb57a55a5236efff
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1508924
Commit-Queue: Jeffrey Cohen <jeffreycohen@chromium.org>
Commit-Queue: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638730}

components/send_tab_to_self/OWNERS

 hansberry@chromium.org
 jeffreycohen@chromium.org
 sebsg@chromium.org
-tgupta@chromium.org
-tinazwang@chromium.org
 
 # COMPONENT: UI>Browser>Sharing