[camerax] Add empty implementation for prepareForVideoRecording not used on Android (#6676)

Adds empty implementation for the camera plugin method `prepareForVideoRecording` that is not used on Android.

Prequel to #6629

Author: camsim99

packages/camera/camera_android_camerax/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.6.4+1
+
+* Adds empty implementation for `prepareForVideoRecording` since this optimization is not used on Android.
+
 ## 0.6.4
 
 * Prevents usage of unsupported concurrent `UseCase`s based on the capabiliites of the camera device.

packages/camera/camera_android_camerax/lib/src/android_camera_camerax.dart

@@ -867,6 +867,15 @@ class AndroidCameraCameraX extends CameraPlatform {
     }
   }
 
+  /// Prepare the capture session for video recording.
+  ///
+  /// This optimization is not used on Android, so this implementation is a
+  /// no-op.
+  @override
+  Future<void> prepareForVideoRecording() {
+    return Future<void>.value();
+  }
+
   /// Configures and starts a video recording. Returns silently without doing
   /// anything if there is currently an active recording.
   ///

packages/camera/camera_android_camerax/pubspec.yaml

@@ -2,7 +2,7 @@ name: camera_android_camerax
 description: Android implementation of the camera plugin using the CameraX library.
 repository: https://github.com/flutter/packages/tree/main/packages/camera/camera_android_camerax
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+camera%22
-version: 0.6.4
+version: 0.6.4+1
 
 environment:
   sdk: ^3.1.0

packages/camera/camera_android_camerax/test/android_camera_camerax_test.dart

@@ -4040,4 +4040,22 @@ void main() {
     verify(
         camera.processCameraProvider!.unbind(<UseCase>[camera.imageAnalysis!]));
   });
+
+  test(
+      'prepareForVideoRecording does not make any calls involving starting video recording',
+      () async {
+    final AndroidCameraCameraX camera = AndroidCameraCameraX();
+
+    // Set directly for test versus calling createCamera.
+    camera.processCameraProvider = MockProcessCameraProvider();
+    camera.recorder = MockRecorder();
+    camera.videoCapture = MockVideoCapture();
+    camera.camera = MockCamera();
+
+    await camera.prepareForVideoRecording();
+    verifyNoMoreInteractions(camera.processCameraProvider);
+    verifyNoMoreInteractions(camera.recorder);
+    verifyNoMoreInteractions(camera.videoCapture);
+    verifyNoMoreInteractions(camera.camera);
+  });
 }