Add dtu to testing/buildbot/OWNERS for chromium.perf.

BUG=642050

Review-Url: https://codereview.chromium.org/2289193003
Cr-Commit-Position: refs/heads/master@{#415589}

testing/buildbot/OWNERS

@@ -18,6 +18,7 @@ per-file chromium.android.json=jbudorick@chromium.org
 per-file chromium.fyi.json=creis@chromium.org
 per-file chromium.fyi.json=nick@chromium.org
 
+per-file *chromium.perf*.json=dtu@chromium.org
 per-file chromium.perf.json=eakuefner@chromium.org
 per-file chromium.perf.json=fmeawad@chromium.org
 per-file chromium.perf.json=simonhatch@chromium.org