Workaround for timeline bar chart selection bug (#1382)

* Workaround for timeline bar chart selection bug

packages/devtools_app/lib/src/timeline/flutter/flutter_frames_chart.dart

diff --git a/packages/devtools_app/lib/src/timeline/flutter/flutter_frames_chart.dart b/packages/devtools_app/lib/src/timeline/flutter/flutter_frames_chart.dart
index 2946b20..33913c4 100644
--- a/packages/devtools_app/lib/src/timeline/flutter/flutter_frames_chart.dart
+++ b/packages/devtools_app/lib/src/timeline/flutter/flutter_frames_chart.dart
@@ -5,7 +5,6 @@
 import 'dart:ui';
 
 import 'package:flutter/material.dart';
-import 'package:flutter/scheduler.dart';
 import 'package:mp_chart/mp/chart/bar_chart.dart';
 import 'package:mp_chart/mp/controller/bar_chart_controller.dart';
 import 'package:mp_chart/mp/core/adapter_android_mp.dart';
@@ -29,6 +28,7 @@
 
 import '../../flutter/auto_dispose_mixin.dart';
 import '../../flutter/controllers.dart';
+import '../../ui/colors.dart';
 import '../../ui/fake_flutter/_real_flutter.dart';
 import '../../ui/theme.dart';
 import '../timeline_controller.dart';
@@ -188,7 +188,7 @@
       drawBarShadow: false,
       description: desc,
       highLightPerTapEnabled: true,
-      marker: SelectedDataPoint(onSelected: frameSelected),
+      marker: SelectedDataPoint(onSelected: onBarSelected),
       selectionListener: this,
     );
 
@@ -196,16 +196,10 @@
     _chartController.setViewPortOffsets(50, 10, 10, 30);
   }
 
-  void frameSelected(int frameIndex) {
-    _controller.frameBasedTimeline.selectFrame(frames[frameIndex]);
+  void onBarSelected(int index) {
+    _controller.frameBasedTimeline.selectFrame(frames[index]);
   }
 
-  /// Light Blue 50 - 200
-  static const mainUiColorLight = Color.fromARGB(0xff, 0x81, 0xD4, 0xFA);
-
-  /// Light Blue 50 - 700
-  static const mainGpuColorLight = Color.fromARGB(0xFF, 0x02, 0x88, 0xD1);
-
   void _initData([bool simulateFeed = false]) {
     // Create place holder for empty chart.
     // TODO(terry): Look at fixing MPFlutterChart to handle empty data entries.
@@ -213,7 +207,7 @@
 
     // Create heap used dataset.
     frameDurationsSet = BarDataSet(_frameDurations, 'Durations')
-      ..setColors1([mainGpuColorLight, mainUiColorLight])
+      ..setColors1([mainGpuColor, mainUiColor])
       ..setDrawValues(false);
 
     // Create a data object with all the data sets - stacked bar.
@@ -330,7 +324,6 @@
     const paddingAroundText = 5;
     const rectangleCurve = 5.0;
 
-    final frameIndex = _entry.x.toInt();
     final yValues = (_entry as BarEntry).yVals;
 
     final num uiDuration = yValues[1];
@@ -376,21 +369,16 @@
     );
     painter.paint(canvas, pos);
     canvas.restore();
-
-    if (onSelected != null && _lastFrameIndex != frameIndex) {
-      // Only fire when a different frame is selected.
-      // TODO(terry): reconfigure this code as selection should not be happening
-      // during paint. This task scheduling is a hack.
-      SchedulerBinding.instance.scheduleTask(
-        () => onSelected(frameIndex),
-        Priority.animation,
-      );
-      _lastFrameIndex = frameIndex;
-    }
   }
 
   @override
-  void refreshContent(Entry e, Highlight highlight) {
+  void refreshContent(Entry e, Highlight highlight) async {
     _entry = e;
+    final frameIndex = _entry.x.toInt();
+    if (onSelected != null && _lastFrameIndex != frameIndex) {
+      _lastFrameIndex = frameIndex;
+      WidgetsBinding.instance
+          .addPostFrameCallback((_) => onSelected(frameIndex));
+    }
   }
 }