Add fbjni wrapper for InspectorFlags (#41913)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/41913

Progress towards an opt-in setup for our new CDP backend.

- Adds and configures an [fbjni](https://github.com/facebookincubator/fbjni) interface for reading `jsinspector_modern::InspectorFlags`, allowing access in Java contexts.

Changelog: [Internal]

Reviewed By: motiz88

Differential Revision: D52040150

fbshipit-source-id: 5459eda2747279633a8312a3979ba29a1e0d1bde

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/bridge/InspectorFlags.java

@@ -0,0 +1,23 @@
+/*
+ * 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.
+ */
+
+package com.facebook.react.bridge;
+
+import com.facebook.proguard.annotations.DoNotStrip;
+
+/** fbjni interface for reading `jsinspector_modern::InspectorFlags`. */
+@DoNotStrip
+public class InspectorFlags {
+  static {
+    ReactBridge.staticInit();
+  }
+
+  @DoNotStrip
+  public static native boolean getEnableModernCDPRegistry();
+
+  private InspectorFlags() {}
+}

packages/react-native/ReactAndroid/src/main/jni/react/jni/JInspectorFlags.cpp

@@ -0,0 +1,27 @@
+/*
+ * 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 "JInspectorFlags.h"
+
+#include <jsinspector-modern/InspectorFlags.h>
+
+namespace facebook::react {
+
+bool JInspectorFlags::getEnableModernCDPRegistry(jni::alias_ref<jclass>) {
+  auto& inspectorFlags = jsinspector_modern::InspectorFlags::getInstance();
+  return inspectorFlags.getEnableModernCDPRegistry();
+}
+
+void JInspectorFlags::registerNatives() {
+  javaClassLocal()->registerNatives({
+      makeNativeMethod(
+          "getEnableModernCDPRegistry",
+          JInspectorFlags::getEnableModernCDPRegistry),
+  });
+}
+
+} // namespace facebook::react

packages/react-native/ReactAndroid/src/main/jni/react/jni/JInspectorFlags.h

@@ -0,0 +1,30 @@
+/*
+ * 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>
+
+namespace facebook::react {
+
+/**
+ * fbjni interface for reading `jsinspector_modern::InspectorFlags`.
+ */
+class JInspectorFlags : public jni::JavaClass<JInspectorFlags> {
+ public:
+  static constexpr auto kJavaDescriptor =
+      "Lcom/facebook/react/bridge/InspectorFlags;";
+
+  static bool getEnableModernCDPRegistry(jni::alias_ref<jclass>);
+
+  static void registerNatives();
+
+ private:
+  JInspectorFlags();
+};
+
+} // namespace facebook::react

packages/react-native/ReactAndroid/src/main/jni/react/jni/OnLoad.cpp

@@ -24,6 +24,7 @@
 
 #ifdef WITH_INSPECTOR
 #include "JInspector.h"
+#include "JInspectorFlags.h"
 #endif
 
 #ifndef WITH_GLOGINIT
@@ -89,6 +90,7 @@ extern "C" JNIEXPORT jint JNI_OnLoad(JavaVM* vm, void* reserved) {
 
 #ifdef WITH_INSPECTOR
     JInspector::registerNatives();
+    JInspectorFlags::registerNatives();
 #endif
   });
 }