Expose an API to enable Concurrent Root on Android (#33645)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/33645

With React 18, we now need to allow users on Fabric to opt-in for Concurrent Root.

This commit adds a new method that can be called on the ReactActivityDelegate
that can be used to set the `concurrentRoot` flag on the `initialProps` on the Render.

Changelog:
[Android] [Added] - Expose an API to enable Concurrent Root on Android

Reviewed By: mdvacca

Differential Revision: D35614879

fbshipit-source-id: 2de83e8115d3748c0346cdec6f31b2ab1f899478

ReactAndroid/src/main/java/com/facebook/react/ReactActivityDelegate.java

@@ -15,6 +15,7 @@ import android.content.res.Configuration;
 import android.os.Build;
 import android.os.Bundle;
 import android.view.KeyEvent;
+import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import com.facebook.infer.annotation.Assertions;
 import com.facebook.react.bridge.Callback;
@@ -33,6 +34,7 @@ public class ReactActivityDelegate {
   private @Nullable PermissionListener mPermissionListener;
   private @Nullable Callback mPermissionsCallback;
   private ReactDelegate mReactDelegate;
+  private boolean mConcurrentRootEnabled;
 
   @Deprecated
   public ReactActivityDelegate(Activity activity, @Nullable String mainComponentName) {
@@ -45,10 +47,27 @@ public class ReactActivityDelegate {
     mMainComponentName = mainComponentName;
   }
 
+  /**
+   * Public API to populate the launch options that will be passed to React. Here you can customize
+   * the values that will be passed as `initialProperties` to the Renderer.
+   *
+   * @return Either null or a key-value map as a Bundle
+   */
   protected @Nullable Bundle getLaunchOptions() {
     return null;
   }
 
+  private @NonNull Bundle composeLaunchOptions() {
+    Bundle composedLaunchOptions = getLaunchOptions();
+    if (isConcurrentRootEnabled()) {
+      if (composedLaunchOptions == null) {
+        composedLaunchOptions = new Bundle();
+      }
+      composedLaunchOptions.putBoolean("concurrentRoot", true);
+    }
+    return composedLaunchOptions;
+  }
+
   protected ReactRootView createRootView() {
     return new ReactRootView(getContext());
   }
@@ -74,9 +93,10 @@ public class ReactActivityDelegate {
 
   protected void onCreate(Bundle savedInstanceState) {
     String mainComponentName = getMainComponentName();
+    Bundle launchOptions = composeLaunchOptions();
     mReactDelegate =
         new ReactDelegate(
-            getPlainActivity(), getReactNativeHost(), mainComponentName, getLaunchOptions()) {
+            getPlainActivity(), getReactNativeHost(), mainComponentName, launchOptions) {
           @Override
           protected ReactRootView createRootView() {
             return ReactActivityDelegate.this.createRootView();
@@ -190,4 +210,16 @@ public class ReactActivityDelegate {
   protected Activity getPlainActivity() {
     return ((Activity) getContext());
   }
+
+  /**
+   * Override this method to enable Concurrent Root on the surface for this Activity. See:
+   * https://reactjs.org/blog/2022/03/29/react-v18.html
+   *
+   * <p>This requires to be rendering on Fabric (i.e. on the New Architecture).
+   *
+   * @return Wether you want to enable Concurrent Root for this surface or not.
+   */
+  protected boolean isConcurrentRootEnabled() {
+    return false;
+  }
 }