From 9bc85d7e54a0896ba5ea1635c52aeb73667dd7a2 Mon Sep 17 00:00:00 2001
From: Jonah Williams <jonahwilliams@google.com>
Date: Mon, 25 Mar 2019 09:42:57 -0700
Subject: [PATCH] wrap Timeline calls in assert (#29861)

---
 packages/flutter/lib/src/material/about.dart | 25 ++++++++++++++------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/packages/flutter/lib/src/material/about.dart b/packages/flutter/lib/src/material/about.dart
index 6a48587c55..787702a30f 100644
--- a/packages/flutter/lib/src/material/about.dart
+++ b/packages/flutter/lib/src/material/about.dart
@@ -380,18 +380,26 @@ class _LicensePageState extends State<LicensePage> {
   bool _loaded = false;
 
   Future<void> _initLicenses() async {
-    final Flow flow = Flow.begin();
-    Timeline.timeSync('_initLicenses()', () { }, flow: flow);
+    int debugFlowId = -1;
+    assert(() {
+      final Flow flow = Flow.begin();
+      Timeline.timeSync('_initLicenses()', () { }, flow: flow);
+      debugFlowId = flow.id;
+      return true;
+    }());
     await for (LicenseEntry license in LicenseRegistry.licenses) {
-      if (!mounted)
+      if (!mounted) {
         return;
-      Timeline.timeSync('_initLicenses()', () { }, flow: Flow.step(flow.id));
+      }
+      assert(() {
+        Timeline.timeSync('_initLicenses()', () { }, flow: Flow.step(debugFlowId));
+        return true;
+      }());
       final List<LicenseParagraph> paragraphs =
         await SchedulerBinding.instance.scheduleTask<List<LicenseParagraph>>(
-          () => license.paragraphs.toList(),
+          license.paragraphs.toList,
           Priority.animation,
           debugLabel: 'License',
-          flow: flow,
         );
       setState(() {
         _licenses.add(const Padding(
@@ -434,7 +442,10 @@ class _LicensePageState extends State<LicensePage> {
     setState(() {
       _loaded = true;
     });
-    Timeline.timeSync('Build scheduled', () { }, flow: Flow.end(flow.id));
+    assert(() {
+      Timeline.timeSync('Build scheduled', () { }, flow: Flow.end(debugFlowId));
+      return true;
+    }());
   }
 
   @override