flags: Extend expiry milestone for preferred interval for video.

R=ellyjones@chromium.org

Change-Id: I042268169b55fe23d3d22933d49a44919cd8653f
Bug: 976583
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2065051
Commit-Queue: Khushal <khushalsagar@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Auto-Submit: Khushal <khushalsagar@chromium.org>
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#742805}

chrome/browser/flag-metadata.json

@@ -3708,7 +3708,7 @@
   {
     "name": "use-preferred-interval-for-video",
     "owners": [ "jiahe.zhang@intel.com", "khushalsagar" ],
-    "expiry_milestone": 82
+    "expiry_milestone": 85
   },
   {
     "name": "use-search-click-for-right-click",