Partial revert of "upgraded usage of BinaryMessenger (#4451)" (#4453)

This reverts commit 9d63517bdcf9b2be805d8ec9c4d218441c1de1e7.

The work to accomodate the breaking change is no longer necessary.
diff --git a/.cirrus.yml b/.cirrus.yml
index 9776d9a..da354c5 100644
--- a/.cirrus.yml
+++ b/.cirrus.yml
@@ -197,10 +197,6 @@
         - export CIRRUS_CHANGE_MESSAGE=""
         - export CIRRUS_COMMIT_MESSAGE=""
         - ./script/tool_runner.sh lint-android # must come after build-examples
-      stable_channel_conditional_script:
-        - if [[ "$CHANNEL" == "stable" ]]; then
-        -   dart ./ci/stable_conditional.dart
-        - fi
       native_unit_test_script:
         # Unsetting CIRRUS_CHANGE_MESSAGE and CIRRUS_COMMIT_MESSAGE as they
         # might include non-ASCII characters which makes Gradle crash.
diff --git a/ci/stable_conditional.dart b/ci/stable_conditional.dart
deleted file mode 100644
index 7664353..0000000
--- a/ci/stable_conditional.dart
+++ /dev/null
@@ -1,67 +0,0 @@
-// Copyright 2013 The Flutter Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-//
-// stable_conditional.dart
-//
-// Performs simple find and replace operations for conditional compilation
-// before executing stable channel tests.
-//
-// Example input:
-//   int main() {
-//     // FLUTTER_STABLE_CONDITIONAL_IF_NOT_STABLE
-//     printf("hello world\n");
-//     // FLUTTER_STABLE_CONDITIONAL_ELSE
-//     // printf("goodbye world\n");
-//     // FLUTTER_STABLE_CONDITIONAL_ENDIF
-//   }
-//
-// Example output:
-//   int main() {
-//     printf("goodbye world\n");
-//   }
-
-import 'dart:convert' show LineSplitter;
-import 'dart:io' show FileSystemEntity, File;
-
-final List<String> _filesToProcess = <String>[
-  'packages/android_intent/android/src/test/java/io/flutter/plugins/androidintent/MethodCallHandlerImplTest.java',
-  'packages/camera/camera/android/src/test/java/io/flutter/plugins/camera/DartMessengerTest.java',
-  'packages/quick_actions/quick_actions/android/src/test/java/io/flutter/plugins/quickactions/QuickActionsTest.java',
-  'packages/url_launcher/url_launcher/android/src/test/java/io/flutter/plugins/urllauncher/MethodCallHandlerImplTest.java',
-];
-
-final RegExp _replacer = RegExp(
-    r'^\s*// FLUTTER_STABLE_CONDITIONAL_IF_NOT_STABLE(.*?)^\s*// FLUTTER_STABLE_CONDITIONAL_ELSE(.*?)^\s*// FLUTTER_STABLE_CONDITIONAL_ENDIF',
-    multiLine: true,
-    dotAll: true);
-final RegExp _commentRemover = RegExp(r'^(\s*)\/\/\s*(.*)');
-const String _newline = '\n';
-
-void _process(FileSystemEntity entity) {
-  const LineSplitter splitter = LineSplitter();
-  final String text = File(entity.path).readAsStringSync();
-  String replaced = '';
-  int index = 0;
-  for (final RegExpMatch match in _replacer.allMatches(text)) {
-    replaced += text.substring(index, match.start);
-    for (final String line in splitter.convert(match.group(2)!)) {
-      final RegExpMatch? commentRemoverMatch = _commentRemover.firstMatch(line);
-      if (commentRemoverMatch != null) {
-        replaced += commentRemoverMatch.group(1)! +
-            commentRemoverMatch.group(2)! +
-            _newline;
-      }
-    }
-    index = match.end;
-  }
-  if (replaced.isNotEmpty) {
-    replaced += text.substring(index, text.length);
-    File(entity.path).writeAsStringSync(replaced);
-    print('modified: ${entity.path}');
-  }
-}
-
-void main(List<String> args) {
-  _filesToProcess.map((String path) => File(path)).forEach(_process);
-}
diff --git a/packages/android_intent/android/src/test/java/io/flutter/plugins/androidintent/MethodCallHandlerImplTest.java b/packages/android_intent/android/src/test/java/io/flutter/plugins/androidintent/MethodCallHandlerImplTest.java
index 012cc9b..0ea03a0 100644
--- a/packages/android_intent/android/src/test/java/io/flutter/plugins/androidintent/MethodCallHandlerImplTest.java
+++ b/packages/android_intent/android/src/test/java/io/flutter/plugins/androidintent/MethodCallHandlerImplTest.java
@@ -55,11 +55,7 @@
     methodCallHandler.startListening(messenger);
 
     verify(messenger, times(1))
-        // FLUTTER_STABLE_CONDITIONAL_IF_NOT_STABLE
-        .setMessageHandler(eq(CHANNEL_NAME), any(BinaryMessageHandler.class), eq(null));
-    // FLUTTER_STABLE_CONDITIONAL_ELSE
-    //     .setMessageHandler(eq(CHANNEL_NAME), any(BinaryMessageHandler.class));
-    // FLUTTER_STABLE_CONDITIONAL_ENDIF
+        .setMessageHandler(eq(CHANNEL_NAME), any(BinaryMessageHandler.class));
   }
 
   @Test
@@ -71,15 +67,9 @@
     methodCallHandler.startListening(secondMessenger);
 
     // Unregisters the first and then registers the second.
-    // FLUTTER_STABLE_CONDITIONAL_IF_NOT_STABLE
-    verify(firstMessenger, times(1)).setMessageHandler(CHANNEL_NAME, null, null);
+    verify(firstMessenger, times(1)).setMessageHandler(CHANNEL_NAME, null);
     verify(secondMessenger, times(1))
-        .setMessageHandler(eq(CHANNEL_NAME), any(BinaryMessageHandler.class), eq(null));
-    // FLUTTER_STABLE_CONDITIONAL_ELSE
-    // verify(firstMessenger, times(1)).setMessageHandler(CHANNEL_NAME, null);
-    // verify(secondMessenger, times(1))
-    //     .setMessageHandler(eq(CHANNEL_NAME), any(BinaryMessageHandler.class));
-    // FLUTTER_STABLE_CONDITIONAL_ENDIF
+        .setMessageHandler(eq(CHANNEL_NAME), any(BinaryMessageHandler.class));
   }
 
   @Test
@@ -89,11 +79,7 @@
 
     methodCallHandler.stopListening();
 
-    // FLUTTER_STABLE_CONDITIONAL_IF_NOT_STABLE
-    verify(messenger, times(1)).setMessageHandler(CHANNEL_NAME, null, null);
-    // FLUTTER_STABLE_CONDITIONAL_ELSE
-    // verify(messenger, times(1)).setMessageHandler(CHANNEL_NAME, null);
-    // FLUTTER_STABLE_CONDITIONAL_ENDIF
+    verify(messenger, times(1)).setMessageHandler(CHANNEL_NAME, null);
   }
 
   @Test
@@ -102,11 +88,7 @@
 
     methodCallHandler.stopListening();
 
-    // FLUTTER_STABLE_CONDITIONAL_IF_NOT_STABLE
-    verify(messenger, never()).setMessageHandler(CHANNEL_NAME, null, null);
-    // FLUTTER_STABLE_CONDITIONAL_ELSE
-    // verify(messenger, never()).setMessageHandler(CHANNEL_NAME, null);
-    // FLUTTER_STABLE_CONDITIONAL_ENDIF
+    verify(messenger, never()).setMessageHandler(CHANNEL_NAME, null);
   }
 
   @Test
diff --git a/packages/camera/camera/android/src/test/java/io/flutter/plugins/camera/DartMessengerTest.java b/packages/camera/camera/android/src/test/java/io/flutter/plugins/camera/DartMessengerTest.java
index 1ce04d6..0a2fc43 100644
--- a/packages/camera/camera/android/src/test/java/io/flutter/plugins/camera/DartMessengerTest.java
+++ b/packages/camera/camera/android/src/test/java/io/flutter/plugins/camera/DartMessengerTest.java
@@ -12,7 +12,6 @@
 
 import android.os.Handler;
 import androidx.annotation.NonNull;
-import androidx.annotation.Nullable;
 import io.flutter.embedding.engine.systemchannels.PlatformChannel;
 import io.flutter.plugin.common.BinaryMessenger;
 import io.flutter.plugin.common.MethodCall;
@@ -32,15 +31,6 @@
   private static class FakeBinaryMessenger implements BinaryMessenger {
     private final List<ByteBuffer> sentMessages = new ArrayList<>();
 
-    // TODO(aaclarke): Remove when https://github.com/flutter/engine/pull/29147 is on stable.
-    // FLUTTER_STABLE_CONDITIONAL_IF_NOT_STABLE
-    @Override
-    public BinaryMessenger.TaskQueue makeBackgroundTaskQueue() {
-      return null;
-    }
-    // FLUTTER_STABLE_CONDITIONAL_ELSE
-    // FLUTTER_STABLE_CONDITIONAL_ENDIF
-
     @Override
     public void send(@NonNull String channel, ByteBuffer message) {
       sentMessages.add(message);
@@ -51,17 +41,8 @@
       send(channel, message);
     }
 
-    // TODO(aaclarke): Remove when https://github.com/flutter/engine/pull/29147 is on stable.
-    // FLUTTER_STABLE_CONDITIONAL_IF_NOT_STABLE
     @Override
-    public void setMessageHandler(
-        @NonNull String channel,
-        BinaryMessageHandler handler,
-        @Nullable BinaryMessenger.TaskQueue taskQueue) {}
-    // FLUTTER_STABLE_CONDITIONAL_ELSE
-    // @Override
-    // public void setMessageHandler(@NonNull String channel, BinaryMessageHandler handler) {}
-    // FLUTTER_STABLE_CONDITIONAL_ENDIF
+    public void setMessageHandler(@NonNull String channel, BinaryMessageHandler handler) {}
 
     List<ByteBuffer> getMessages() {
       return new ArrayList<>(sentMessages);
diff --git a/packages/quick_actions/quick_actions/android/src/test/java/io/flutter/plugins/quickactions/QuickActionsTest.java b/packages/quick_actions/quick_actions/android/src/test/java/io/flutter/plugins/quickactions/QuickActionsTest.java
index 2b6fb49..208a119 100644
--- a/packages/quick_actions/quick_actions/android/src/test/java/io/flutter/plugins/quickactions/QuickActionsTest.java
+++ b/packages/quick_actions/quick_actions/android/src/test/java/io/flutter/plugins/quickactions/QuickActionsTest.java
@@ -33,15 +33,6 @@
   private static class TestBinaryMessenger implements BinaryMessenger {
     public MethodCall lastMethodCall;
 
-    // TODO(aaclarke): Remove when https://github.com/flutter/engine/pull/29147 is on stable.
-    // FLUTTER_STABLE_CONDITIONAL_IF_NOT_STABLE
-    @Override
-    public BinaryMessenger.TaskQueue makeBackgroundTaskQueue() {
-      return null;
-    }
-    // FLUTTER_STABLE_CONDITIONAL_ELSE
-    // FLUTTER_STABLE_CONDITIONAL_ENDIF
-
     @Override
     public void send(@NonNull String channel, @Nullable ByteBuffer message) {
       send(channel, message, null);
@@ -58,21 +49,10 @@
       }
     }
 
-    // TODO(aaclarke): Remove when https://github.com/flutter/engine/pull/29147 is on stable.
-    // FLUTTER_STABLE_CONDITIONAL_IF_NOT_STABLE
     @Override
-    public void setMessageHandler(
-        @NonNull String channel,
-        @Nullable BinaryMessageHandler handler,
-        @Nullable BinaryMessenger.TaskQueue taskQueue) {
+    public void setMessageHandler(@NonNull String channel, @Nullable BinaryMessageHandler handler) {
       // Do nothing.
     }
-    // FLUTTER_STABLE_CONDITIONAL_ELSE
-    // @Override
-    // public void setMessageHandler(
-    //    @NonNull String channel,
-    //    @Nullable BinaryMessageHandler handler) {}
-    // FLUTTER_STABLE_CONDITIONAL_ENDIF
   }
 
   static final int SUPPORTED_BUILD = 25;
diff --git a/packages/url_launcher/url_launcher/android/src/test/java/io/flutter/plugins/urllauncher/MethodCallHandlerImplTest.java b/packages/url_launcher/url_launcher/android/src/test/java/io/flutter/plugins/urllauncher/MethodCallHandlerImplTest.java
index 6b544c7..5e08113 100644
--- a/packages/url_launcher/url_launcher/android/src/test/java/io/flutter/plugins/urllauncher/MethodCallHandlerImplTest.java
+++ b/packages/url_launcher/url_launcher/android/src/test/java/io/flutter/plugins/urllauncher/MethodCallHandlerImplTest.java
@@ -44,11 +44,7 @@
     methodCallHandler.startListening(messenger);
 
     verify(messenger, times(1))
-        // FLUTTER_STABLE_CONDITIONAL_IF_NOT_STABLE
-        .setMessageHandler(eq(CHANNEL_NAME), any(BinaryMessageHandler.class), eq(null));
-    // FLUTTER_STABLE_CONDITIONAL_ELSE
-    //     .setMessageHandler(eq(CHANNEL_NAME), any(BinaryMessageHandler.class));
-    // FLUTTER_STABLE_CONDITIONAL_ENDIF
+        .setMessageHandler(eq(CHANNEL_NAME), any(BinaryMessageHandler.class));
   }
 
   @Test
@@ -60,15 +56,9 @@
     methodCallHandler.startListening(secondMessenger);
 
     // Unregisters the first and then registers the second.
-    // FLUTTER_STABLE_CONDITIONAL_IF_NOT_STABLE
-    verify(firstMessenger, times(1)).setMessageHandler(CHANNEL_NAME, null, null);
+    verify(firstMessenger, times(1)).setMessageHandler(CHANNEL_NAME, null);
     verify(secondMessenger, times(1))
-        .setMessageHandler(eq(CHANNEL_NAME), any(BinaryMessageHandler.class), eq(null));
-    // FLUTTER_STABLE_CONDITIONAL_ELSE
-    // verify(firstMessenger, times(1)).setMessageHandler(CHANNEL_NAME, null);
-    // verify(secondMessenger, times(1))
-    //     .setMessageHandler(eq(CHANNEL_NAME), any(BinaryMessageHandler.class));
-    // FLUTTER_STABLE_CONDITIONAL_ENDIF
+        .setMessageHandler(eq(CHANNEL_NAME), any(BinaryMessageHandler.class));
   }
 
   @Test
@@ -78,11 +68,7 @@
 
     methodCallHandler.stopListening();
 
-    // FLUTTER_STABLE_CONDITIONAL_IF_NOT_STABLE
-    verify(messenger, times(1)).setMessageHandler(CHANNEL_NAME, null, null);
-    // FLUTTER_STABLE_CONDITIONAL_ELSE
-    // verify(messenger, times(1)).setMessageHandler(CHANNEL_NAME, null);
-    // FLUTTER_STABLE_CONDITIONAL_ENDIF
+    verify(messenger, times(1)).setMessageHandler(CHANNEL_NAME, null);
   }
 
   @Test
@@ -91,11 +77,7 @@
 
     methodCallHandler.stopListening();
 
-    // FLUTTER_STABLE_CONDITIONAL_IF_NOT_STABLE
-    verify(messenger, never()).setMessageHandler(CHANNEL_NAME, null, null);
-    // FLUTTER_STABLE_CONDITIONAL_ELSE
-    // verify(messenger, never()).setMessageHandler(CHANNEL_NAME, null);
-    // FLUTTER_STABLE_CONDITIONAL_ENDIF
+    verify(messenger, never()).setMessageHandler(CHANNEL_NAME, null);
   }
 
   @Test