[camera_android] Removes usage of _ambiguate method in tests (#4948)

Since the minimum Flutter version for this package is +3.0, we can remove the `_ambiguate` method. Because this PR only affects tests, we don't need to publish a new version.

Part of flutter/flutter#111841

Author: nilsreichardt

packages/camera/camera_android/test/android_camera_test.dart

@@ -32,15 +32,14 @@ void main() {
     // registerWith is called very early in initialization the bindings won't
     // have been initialized. While registerWith could intialize them, that
     // could slow down startup, so instead the handler should be set up lazily.
-    final ByteData? response =
-        await _ambiguate(TestDefaultBinaryMessengerBinding.instance)!
-            .defaultBinaryMessenger
-            .handlePlatformMessage(
-                AndroidCamera.deviceEventChannelName,
-                const StandardMethodCodec().encodeMethodCall(const MethodCall(
-                    'orientation_changed',
-                    <String, Object>{'orientation': 'portraitDown'})),
-                (ByteData? data) {});
+    final ByteData? response = await TestDefaultBinaryMessengerBinding
+        .instance.defaultBinaryMessenger
+        .handlePlatformMessage(
+            AndroidCamera.deviceEventChannelName,
+            const StandardMethodCodec().encodeMethodCall(const MethodCall(
+                'orientation_changed',
+                <String, Object>{'orientation': 'portraitDown'})),
+            (ByteData? data) {});
     expect(response, null);
   });
 
@@ -422,8 +421,7 @@ void main() {
       const DeviceOrientationChangedEvent event =
           DeviceOrientationChangedEvent(DeviceOrientation.portraitUp);
       for (int i = 0; i < 3; i++) {
-        await _ambiguate(TestDefaultBinaryMessengerBinding.instance)!
-            .defaultBinaryMessenger
+        await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
             .handlePlatformMessage(
                 AndroidCamera.deviceEventChannelName,
                 const StandardMethodCodec().encodeMethodCall(
@@ -1146,9 +1144,3 @@ void main() {
     });
   });
 }
-
-/// This allows a value of type T or T? to be treated as a value of type T?.
-///
-/// We use this so that APIs that have become non-nullable can still be used
-/// with `!` and `?` on the stable branch.
-T? _ambiguate<T>(T? value) => value;

packages/camera/camera_android/test/method_channel_mock.dart

@@ -11,8 +11,7 @@ class MethodChannelMock {
     this.delay,
     required this.methods,
   }) : methodChannel = MethodChannel(channelName) {
-    _ambiguate(TestDefaultBinaryMessengerBinding.instance)!
-        .defaultBinaryMessenger
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
         .setMockMethodCallHandler(methodChannel, _handler);
   }
 
@@ -39,9 +38,3 @@ class MethodChannelMock {
     });
   }
 }
-
-/// This allows a value of type T or T? to be treated as a value of type T?.
-///
-/// We use this so that APIs that have become non-nullable can still be used
-/// with `!` and `?` on the stable branch.
-T? _ambiguate<T>(T? value) => value;