Add flag owner for UAv2.

Change-Id: I29dbfa090291d933582fdeaece594808dea5e046
Reviewed-on: https://chromium-review.googlesource.com/c/1344580Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Mustaq Ahmed <mustaq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609829}

chrome/browser/flag-metadata.json

@@ -3205,7 +3205,7 @@
   },
   {
     "name": "user-activation-v2",
-    // "owners": [ "your-team" ],
+    "owners": [ "mustaq@chromium.org" ],
     "expiry_milestone": 76
   },
   {