Add OWNERS file to chrome/android/shared_preference_files

Adds a new OWNERS file for the shared preference file directory.
The files in here are simple, test-only config files, so it's set to
allow any commiter to provide a rubber stamp.

Change-Id: Ib858380befc6103a615cb84259bcc1dbc813bda3
Reviewed-on: https://chromium-review.googlesource.com/994143Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547851}

chrome/android/shared_preference_files/OWNERS

+bsheedy@chromium.org
+
+per-file *.json=*
\ No newline at end of file