[background sync] Remove old TODO

Remove an old TODO that no longer applies.

Change-Id: Ib17cc59de2d4a38a31e5d9dce0eafa09687f7af5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2532885
Auto-Submit: Nina Satragno <nsatragno@chromium.org>
Commit-Queue: Peter Beverloo <peter@chromium.org>
Reviewed-by: Peter Beverloo <peter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827356}

components/background_sync/background_sync_permission_context.h

@@ -14,7 +14,6 @@
 // The permission status is ALLOW by default and can be changed globally or on a
 // per-site basis from the content settings page. The user is not prompted for
 // permission.
-// TODO(nsatragno): actually implement the UI to allow changing the setting.
 class BackgroundSyncPermissionContext
     : public permissions::PermissionContextBase {
  public: