Extend surfaces-for-video flag lifetime

Until WebView supports this feature, I think this flag needs to
continue to live, if only for easy testing.

Also change its ownership.

Bug: 746182,1013777
Change-Id: Ifa71a41b7f5be7de369664083af0e53566bf9c37
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1857340
Commit-Queue: enne <enne@chromium.org>
Auto-Submit: enne <enne@chromium.org>
Reviewed-by: Khushal <khushalsagar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#705313}

chrome/browser/flag-metadata.json

@@ -1766,8 +1766,8 @@
   },
   {
     "name": "enable-surfaces-for-videos",
-    "owners": [ "enne", "lethalantidote", "mlamouri" ],
-    "expiry_milestone": 76
+    "owners": [ "ericrk", "khushalsagar", "mlamouri" ],
+    "expiry_milestone": 85
   },
   {
     "name": "enable-sxg-prefetch-cache-for-navigations",