Delay expiration of portals flags from M90 to M100.

These will be needed past M90, and it's convenient to update now to avoid forgetting later.

Change-Id: I3eb65f5bd8bc46bdcb488ed1e020e71e2d353d9f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2593473
Commit-Queue: Jeremy Roman <jbroman@chromium.org>
Commit-Queue: Lucas Gadani <lfg@chromium.org>
Auto-Submit: Jeremy Roman <jbroman@chromium.org>
Reviewed-by: Lucas Gadani <lfg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#837234}

chrome/browser/flag-metadata.json

@@ -2068,12 +2068,12 @@
   {
     "name": "enable-portals",
     "owners": [ "jbroman", "//third_party/blink/renderer/core/html/portal/OWNERS" ],
-    "expiry_milestone": 90
+    "expiry_milestone": 100
   },
   {
     "name": "enable-portals-cross-origin",
     "owners": [ "jbroman", "//third_party/blink/renderer/core/html/portal/OWNERS" ],
-    "expiry_milestone": 90
+    "expiry_milestone": 100
   },
   {
     "name": "enable-preconnect-to-search",