Expose scheduler through FabricUIManager

Summary:
Allows to access `react::renderer::Scheduler` given `FabricUIManager` from Java side.

Changelog: [Added] Added `FabricUIManager` binding with FBJNI

Reviewed By: javache

Differential Revision: D35313399

fbshipit-source-id: 54e7adcceae40368c2735ddfc8a083f87b08dc5e

Author: cortinico

ReactAndroid/src/main/java/com/facebook/react/fabric/jni/Binding.h

@@ -43,6 +43,8 @@ class Binding : public jni::HybridClass<Binding>,
 
   static void registerNatives();
 
+  std::shared_ptr<Scheduler> getScheduler();
+
  private:
   void setConstraints(
       jint surfaceId,
@@ -133,7 +135,6 @@ class Binding : public jni::HybridClass<Binding>,
   std::shared_ptr<FabricMountingManager> mountingManager_;
   std::shared_ptr<Scheduler> scheduler_;
 
-  std::shared_ptr<Scheduler> getScheduler();
   std::shared_ptr<FabricMountingManager> verifyMountingManager(
       std::string const &locationHint);
 

ReactAndroid/src/main/java/com/facebook/react/fabric/jni/JFabricUIManager.cpp

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include "JFabricUIManager.h"
+
+namespace facebook::react {
+
+Binding *JFabricUIManager::getBinding() {
+  static const auto bindingField =
+      javaClassStatic()->getField<Binding::javaobject>("mBinding");
+
+  return getFieldValue(bindingField)->cthis();
+}
+} // namespace facebook::react

ReactAndroid/src/main/java/com/facebook/react/fabric/jni/JFabricUIManager.h

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <fbjni/fbjni.h>
+#include "Binding.h"
+
+using namespace facebook::jni;
+
+namespace facebook::react {
+
+class JFabricUIManager : public JavaClass<JFabricUIManager> {
+ public:
+  static constexpr auto kJavaDescriptor =
+      "Lcom/facebook/react/fabric/FabricUIManager;";
+
+  Binding *getBinding();
+};
+
+} // namespace facebook::react