Add chouinard to android/preferences/OWNERS

Add chouinard@chromium.org to
//chrome/browser/android/preferences/OWNERS

Change-Id: I71a160063df1e7914e47a15b56fa4733dd9ffda5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1879820Reviewed-by: Theresa  <twellington@chromium.org>
Commit-Queue: Natalie Chouinard <chouinard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#709259}

chrome/browser/android/preferences/OWNERS

 twellington@chromium.org
+chouinard@chromium.org
 
 # COMPONENT: UI>Browser>Mobile>Settings