Add owners for chrome/browser/media_gallery

BUG=NONE
TEST=NONE
NOTRY=TRUE


Review URL: https://chromiumcodereview.appspot.com/10832016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@148411 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/media_gallery/OWNERS

+estade@chromium.org
+kmadhusu@chromium.org
+thestig@chromium.org
+vandebo@chromium.org
+