flags: replace TODO with bug reference

Bug: None
Change-Id: Ia159aa0844f5473b0b7f360d9819919e93c45dbf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3103714
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#913063}

components/flags_ui/flags_test_helpers.cc

@@ -291,7 +291,8 @@ void EnsureFlagsAreListedInAlphabeticalOrder() {
                              FlagFile::kFlagNeverExpire);
 }
 
-// TODO(ellyjones): Does this / should this run on iOS as well?
+// TODO(https://crbug.com/1241068): Call this from the iOS flags unittests once
+// flag expiration is supported there.
 void EnsureRecentUnexpireFlagsArePresent(
     const base::span<const flags_ui::FeatureEntry>& entries,
     int current_milestone) {