flags: assign enable-app-banners

Expiration is left at the default (M76).

Bug: 959086
Change-Id: I7c87dc520bbb5a310e5a36120c3e3add7ead23b8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1610495
Auto-Submit: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: Dominick Ng <dominickn@chromium.org>
Reviewed-by: Dominick Ng <dominickn@chromium.org>
Cr-Commit-Position: refs/heads/master@{#659734}

chrome/browser/flag-metadata.json

@@ -695,7 +695,7 @@
   },
   {
     "name": "enable-app-banners",
-    // "owners": [ "your-team" ],
+    "owners": [ "desktop-pwas-team@google.com" ],
     "expiry_milestone": 76
   },
   {