[Android] Update OWNERS information (bottombar)

The clank team is trying to review the ownership
of all `/android` directories and add/update OWNERS
as part of an effort to normalize code health metrics
across different data sources.

https://docs.google.com/document/d/17QautLenV9WAiFN240ZE0SBK2nHCpwu_cgcvV95-lvE

Bug: 1112872
Change-Id: I3861be0e6d1488b3173169bf776e463e35c32edd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2356444
Commit-Queue: Fred Mello <fredmello@chromium.org>
Auto-Submit: Fred Mello <fredmello@chromium.org>
Reviewed-by: Theresa  <twellington@chromium.org>
Reviewed-by: Donn Denman <donnd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#799262}

chrome/android/java/src/org/chromium/chrome/browser/compositor/bottombar/OWNERS

@@ -4,3 +4,4 @@ per-file Overlay*=mdjones@chromium.org
 
 # TEAM: contextual-search-dev@chromium.org
 # COMPONENT: UI>Browser>Search>ContextualSearch
+# OS: Android

chrome/browser/android/bottombar/OWNERS

+file://chrome/android/java/src/org/chromium/chrome/browser/compositor/bottombar/OWNERS