Add test case for Flutter Issue #27677 as a benchmark. (#34870)

* Add test case for Flutter Issue #27677 as a benchmark.

See https://github.com/flutter/flutter/issues/27677

I got the following results running the test on a Moto E2 which
will help us determine how much we can gain by analyzing the
operations and eliminating unnecessary repaints based on
dirty rectangles/regions.

no blurs       - avg 216.0 fps over 3 samples
blur the group - avg  22.9 fps over 3 samples
blur each txt  - avg   3.4 fps over 3 samples

* Added the new benchmark to be tracked on the dashboard.

dev/devicelab/bin/tasks/backdrop_filter_perf__timeline_summary.dart

diff --git a/dev/devicelab/bin/tasks/backdrop_filter_perf__timeline_summary.dart b/dev/devicelab/bin/tasks/backdrop_filter_perf__timeline_summary.dart
new file mode 100644
index 0000000..4e7a306
--- /dev/null
+++ b/dev/devicelab/bin/tasks/backdrop_filter_perf__timeline_summary.dart
@@ -0,0 +1,14 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:async';
+
+import 'package:flutter_devicelab/tasks/perf_tests.dart';
+import 'package:flutter_devicelab/framework/adb.dart';
+import 'package:flutter_devicelab/framework/framework.dart';
+
+Future<void> main() async {
+  deviceOperatingSystem = DeviceOperatingSystem.android;
+  await task(createBackdropFilterPerfTest());
+}

dev/devicelab/lib/tasks/perf_tests.dart

diff --git a/dev/devicelab/lib/tasks/perf_tests.dart b/dev/devicelab/lib/tasks/perf_tests.dart
index 7fa6059..c0afb07 100644
--- a/dev/devicelab/lib/tasks/perf_tests.dart
+++ b/dev/devicelab/lib/tasks/perf_tests.dart
@@ -54,6 +54,14 @@
   ).run;
 }
 
+TaskFunction createBackdropFilterPerfTest() {
+  return PerfTest(
+    '${flutterDirectory.path}/dev/benchmarks/macrobenchmarks',
+    'test_driver/backdrop_filter_perf.dart',
+    'backdrop_filter_perf',
+  ).run;
+}
+
 TaskFunction createFlutterGalleryStartupTest() {
   return StartupTest(
     '${flutterDirectory.path}/examples/flutter_gallery',

dev/devicelab/manifest.yaml

diff --git a/dev/devicelab/manifest.yaml b/dev/devicelab/manifest.yaml
index f142262..5ecb300 100644
--- a/dev/devicelab/manifest.yaml
+++ b/dev/devicelab/manifest.yaml
@@ -171,6 +171,13 @@
     stage: devicelab
     required_agent_capabilities: ["mac/android"]
 
+  backdrop_filter_perf__timeline_summary:
+    description: >
+      Measures the runtime performance of backdrop filter blurs on Android.
+    stage: devicelab
+    required_agent_capabilities: ["mac/android"]
+    flaky: true
+
   flavors_test:
     description: >
       Checks that flavored builds work on Android.