Extends a few flags for notification.

This CL extends a few notification related flags.

Bug: NONE
Change-Id: I0e2d0d642215a34e4252c0cd4196ec17448245f3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2415329Reviewed-by: David Trainor <dtrainor@chromium.org>
Commit-Queue: Xing Liu <xingliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#807950}

chrome/browser/flag-metadata.json

@@ -3213,7 +3213,7 @@
   {
     "name": "notification-scheduler-debug-options",
     "owners": [ "//chrome/browser/notifications/scheduler/OWNERS" ],
-    "expiry_milestone": 86
+    "expiry_milestone": 89
   },
   {
     "name": "ntp-dismiss-promos",
@@ -4496,12 +4496,12 @@
   {
     "name": "update-notification-scheduling-integration",
     "owners": [ "//chrome/browser/updates/OWNERS" ],
-    "expiry_milestone": 86
+    "expiry_milestone": 89
   },
   {
     "name": "update-notification-scheduling-show-immediately",
     "owners": [ "//chrome/browser/updates/OWNERS" ],
-    "expiry_milestone": 86
+    "expiry_milestone": 89
   },
   {
     "name": "updated_cellular_activation_ui",