Update OWNERS for media/ to match current team.

- Adds watk@, chcunningham@, and hubbe@ to OWNERS for media/.
- Syncs OWNERS lists with latest team roster.
- Deletes content/test/data OWNERS since that has parent *.

FFmpeg will have to be updated separately. Forgot to do this
after committership, sorry!

BUG=all that the future has to offer.
TEST=seem like cool folk.

Review URL: https://codereview.chromium.org/1744583002

Cr-Commit-Position: refs/heads/master@{#377980}

diff --git a/media/OWNERS b/media/OWNERS
index e65ac6fb..7209529 100644
--- a/media/OWNERS
+++ b/media/OWNERS

@@ -8,10 +8,13 @@
 # and to load balance. Only use OWNERS in this file for these subdirectories
 # when doing refactorings and general cleanups.
 
+chcunningham@chromium.org
 dalecurtis@chromium.org
 ddorwin@chromium.org
+hubbe@chromium.org
 jrummell@chromium.org
 sandersd@chromium.org
+watk@chromium.org
 wolenetz@chromium.org
 xhwang@chromium.org