Force Impeller backend for android_engine_test, and test both OpenGLES and Vulkan (#162089)

A few changes in this PR (could have been split up, but that would take
an extra 4 hours - 2 days in CI time):

- Removed the old `flutter_driver_android_test` shards and references
- Override `AndroidManifest.xml` per backend, forcing that backend to be
used (no fallbacks) or it fails
- Bumps the Android emulator to 35 due to the use of magic strings, I
think

The check for the Impeller backend actually being used is the honor
system right now, as a bug in `flutter drive`
(https://github.com/flutter/flutter/issues/162087) prevents me from
seeing error output, meaning that it's impossible to be sure a
particular Impeller backend is used (or understand why a crash happens),
so I guess I'll work on that next.

Due to https://github.com/flutter/flutter/issues/162088, we were
accidentally running our Vulkan tests as OpenGLES 🤦🏼 .

.ci.yaml

@@ -1526,7 +1526,7 @@ targets:
       - engine/**
       - DEPS
 
-  - name: Linux_android_emu_34 android_engine_vulkan_tests
+  - name: Linux_android_emu android_engine_vulkan_tests
     recipe: flutter/flutter_drone
     bringup: true
     timeout: 60
@@ -1539,7 +1539,7 @@ targets:
           {"dependency": "goldctl", "version": "git_revision:2387d6fff449587eecbb7e45b2692ca0710b63b9"}
         ]
 
-  - name: Linux_android_emu_34 android_engine_opengles_tests
+  - name: Linux_android_emu android_engine_opengles_tests
     recipe: flutter/flutter_drone
     bringup: true
     timeout: 60
@@ -1552,32 +1552,6 @@ targets:
           {"dependency": "goldctl", "version": "git_revision:2387d6fff449587eecbb7e45b2692ca0710b63b9"}
         ]
 
-  - name: Linux_android_emu flutter_driver_android_test
-    recipe: flutter/flutter_drone
-    bringup: true
-    timeout: 60
-    properties:
-      shard: android_engine_tests
-      tags: >
-         ["framework", "hostonly", "shard", "linux"]
-      dependencies: >-
-        [
-          {"dependency": "goldctl", "version": "git_revision:2387d6fff449587eecbb7e45b2692ca0710b63b9"}
-        ]
-      presubmit_max_attempts: "2"
-
-  - name: Linux_android_emu_34 flutter_driver_android_test
-    recipe: flutter/flutter_drone
-    timeout: 60
-    properties:
-      shard: android_engine_tests
-      tags: >
-         ["framework", "hostonly", "shard", "linux"]
-      dependencies: >-
-        [
-          {"dependency": "goldctl", "version": "git_revision:2387d6fff449587eecbb7e45b2692ca0710b63b9"}
-        ]
-
   - name: Linux web_benchmarks_canvaskit
     recipe: devicelab/devicelab_drone
     presubmit: false

dev/bots/suite_runners/run_android_engine_tests.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'package:file/file.dart';
+import 'package:file/local.dart';
 import 'package:glob/glob.dart';
 import 'package:glob/list_local_fs.dart';
 import 'package:path/path.dart' as path;
@@ -32,12 +33,32 @@ import '../utils.dart';
 /// to determine flakiness in the *same* state, or want better debugging, see
 /// `dev/integration_tests/android_engine_test/README.md`.
 Future<void> runAndroidEngineTests({required ImpellerBackend impellerBackend}) async {
-  print('Running Flutter Driver Android tests...');
+  print('Running Flutter Driver Android tests (backend=$impellerBackend)');
 
   final String androidEngineTestPath = path.join('dev', 'integration_tests', 'android_engine_test');
   final List<FileSystemEntity> mains = Glob('$androidEngineTestPath/lib/**_main.dart').listSync();
+
+  final File androidManifestXml = const LocalFileSystem().file(
+    path.join(androidEngineTestPath, 'android', 'app', 'src', 'main', 'AndroidManifest.xml'),
+  );
+  final String androidManifestContents = androidManifestXml.readAsStringSync();
+
+  try {
+    // Replace whatever the current backend is with the specified backend.
+    final RegExp impellerBackendMetadata = RegExp(_impellerBackendMetadata(value: '.*'));
+    androidManifestXml.writeAsStringSync(
+      androidManifestContents.replaceFirst(
+        impellerBackendMetadata,
+        _impellerBackendMetadata(value: impellerBackend.name),
+      ),
+    );
+
+    // Stdout will produce: "Using the Impeller rendering backend (.*)"
+    // TODO(matanlurey): Enable once `flutter drive` retains error logs.
+    // final RegExp impellerStdoutPattern = RegExp('Using the Imepller rendering backend (.*)');
+
     for (final FileSystemEntity file in mains) {
-    await runCommand(
+      final CommandResult result = await runCommand(
         'flutter',
         <String>[
           'drive',
@@ -53,7 +74,37 @@ Future<void> runAndroidEngineTests({required ImpellerBackend impellerBackend}) a
         workingDirectory: androidEngineTestPath,
         environment: <String, String>{'ANDROID_ENGINE_TEST_GOLDEN_VARIANT': impellerBackend.name},
       );
+      final String? stdout = result.flattenedStdout;
+      if (stdout == null) {
+        foundError(<String>['No stdout produced.']);
+        continue;
+      }
+
+      // TODO(matanlurey): Enable once `flutter drive` retains error logs.
+      // https://github.com/flutter/flutter/issues/162087.
+      //
+      // final Match? stdoutMatch = impellerStdoutPattern.firstMatch(stdout);
+      // if (stdoutMatch == null) {
+      //   foundError(<String>['Could not find pattern ${impellerStdoutPattern.pattern}.', stdout]);
+      //   continue;
+      // }
+
+      // final String reportedBackend = stdoutMatch.group(1)!.toLowerCase();
+      // if (reportedBackend != impellerBackend.name) {
+      //   foundError(<String>[
+      //     'Reported Imepller backend was $reportedBackend, expected ${impellerBackend.name}',
+      //   ]);
+      //   continue;
+      // }
+    }
+  } finally {
+    // Restore original contents.
+    androidManifestXml.writeAsStringSync(androidManifestContents);
   }
 }
 
+String _impellerBackendMetadata({required String value}) {
+  return '<meta-data android:name="io.flutter.embedding.android.ImpellerBackend" android:value="$value" />';
+}
+
 enum ImpellerBackend { vulkan, opengles }

dev/bots/test.dart

@@ -137,9 +137,6 @@ Future<void> main(List<String> args) async {
       'web_skwasm_tests': webTestsSuite.runWebSkwasmUnitTests,
       // All web integration tests
       'web_long_running_tests': webTestsSuite.webLongRunningTestsRunner,
-      // TODO(matanlurey): Remove once a post-submit runs with the new shards.
-      // (Part of https://github.com/flutter/flutter/issues/161333)
-      'android_engine_tests': () => runAndroidEngineTests(impellerBackend: ImpellerBackend.vulkan),
       'android_engine_vulkan_tests':
           () => runAndroidEngineTests(impellerBackend: ImpellerBackend.vulkan),
       'android_engine_opengles_tests':

dev/integration_tests/android_engine_test/README.md

@@ -19,7 +19,8 @@ See [`dev/bots/suite_runners/run_android_engine_tests.dart`](../../bots/suite_ru
 
 ```sh
 # TIP: If golden-files do not exist locally, this command will fail locally.
-SHARD=android_engine_tests bin/cache/dart-sdk/bin/dart dev/bots/test.dart
+SHARD=android_engine_vulkan_tests bin/cache/dart-sdk/bin/dart dev/bots/test.dart
+SHARD=android_engine_opengles_tests bin/cache/dart-sdk/bin/dart dev/bots/test.dart
 ```
 
 ## Running the apps and tests

dev/integration_tests/android_engine_test/android/app/src/main/AndroidManifest.xml

@@ -31,9 +31,9 @@ found in the LICENSE file. -->
         </activity>
         <!-- Don't delete the meta-data below.
              This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
-        <meta-data
+        <meta-data android:name="flutterEmbedding" android:value="2" />
-            android:name="flutterEmbedding"
+        <meta-data android:name="io.flutter.embedding.android.EnableImpeller" android:value="true" />
-            android:value="2" />
+        <meta-data android:name="io.flutter.embedding.android.ImpellerBackend" android:value="vulkan" />
     </application>
     <!-- Required to query activities that can process text, see:
          https://developer.android.com/training/package-visibility and