Add self to media in WATCHLISTS

I've subscribed to feature-media-reviews@chromium.org, but the Blink
changes are drowned in a flood of Chromium reviews, so until there
is a separate list for Blink changes, just watch it directly.

BUG=none
NOTRY=true

Review URL: https://codereview.chromium.org/54773004

git-svn-id: svn://svn.chromium.org/blink/trunk@161151 bbb929c8-8fbe-4397-9dbb-9b2b20218538