Extend --enable-native-notifications until M90

Bug: 1113148
Change-Id: Ie562df1e71f37bc8618d083ae68fb321a5cca1fb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2351919
Commit-Queue: Peter Beverloo <peter@chromium.org>
Commit-Queue: Richard Knoll <knollr@chromium.org>
Auto-Submit: Peter Beverloo <peter@chromium.org>
Reviewed-by: Richard Knoll <knollr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#797245}

chrome/browser/flag-metadata.json

@@ -1760,8 +1760,8 @@
   },
   {
     "name": "enable-native-notifications",
-    "owners": [ "peter", "finnur" ],
-    "expiry_milestone": 84
+    "owners": [ "peter", "finnur", "knollr" ],
+    "expiry_milestone": 90
   },
   {
     "name": "enable-navigation-predictor",