Added a benchmark for ImageCache (#33814)

* Add an image cache benchmark for a monochrome image

dev/devicelab/bin/tasks/flutter_gallery__image_cache_memory.dart

diff --git a/dev/devicelab/bin/tasks/flutter_gallery__image_cache_memory.dart b/dev/devicelab/bin/tasks/flutter_gallery__image_cache_memory.dart
new file mode 100644
index 0000000..c3bc789
--- /dev/null
+++ b/dev/devicelab/bin/tasks/flutter_gallery__image_cache_memory.dart
@@ -0,0 +1,17 @@
+// Copyright 2016 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/framework/framework.dart';
+import 'package:flutter_devicelab/framework/utils.dart';
+import 'package:flutter_devicelab/tasks/perf_tests.dart';
+
+Future<void> main() async {
+  await task(MemoryTest(
+    '${flutterDirectory.path}/examples/flutter_gallery',
+    'test_memory/image_cache_memory.dart',
+    'io.flutter.demo.gallery',
+  ).run);
+}

dev/devicelab/manifest.yaml

diff --git a/dev/devicelab/manifest.yaml b/dev/devicelab/manifest.yaml
index 9392670..02b57ce 100644
--- a/dev/devicelab/manifest.yaml
+++ b/dev/devicelab/manifest.yaml
@@ -527,6 +527,13 @@
     stage: devicelab
     required_agent_capabilities: ["linux/android"]
 
+  flutter_gallery__image_cache_memory:
+    description: >
+      Measures memory usage for a list of large red squares in smaller containers.
+    stage: devicelab
+    required_agent_capabilities: ["linux/android"]
+    flaky: true
+
   analyzer_benchmark:
     description: >
       Measures the speed of Dart analyzer.