Add InspectorFlags, conditionally disable Hermes CDP registration (fa…

…cebook#41672)

Summary:

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

- Adds `InspectorFlags.h`, a singleton intended to allow convienient access to static boolean feature flags for the new CDP backend/inspector features across platforms. This will be written to in upcoming diffs, with the accessor for `enable_modern_cdp_registry` soft-defaulting to `false` here.
- References this to conditionally disable CDP registration in `HermesExecutorFactory` (Bridge) and `HermesInstance` (Bridgeless) code paths.
- Stubs a `false` value for `react_native_devx:enable_modern_cdp_registry` in `EmptyReactNativeConfig` (documentation/convenience point for open source partners and integrators).

Changelog: [Internal]

Differential Revision: D51563107

packages/react-native/ReactCommon/hermes/executor/HermesExecutorFactory.cpp

@@ -13,6 +13,7 @@
 #include <cxxreact/SystraceSection.h>
 #include <hermes/hermes.h>
 #include <jsi/decorator.h>
+#include <jsinspector-modern/InspectorFlags.h>
 
 #include <hermes/inspector-modern/chrome/Registration.h>
 #include <hermes/inspector/RuntimeAdapter.h>
@@ -200,11 +201,14 @@ std::unique_ptr<JSExecutor> HermesExecutorFactory::createJSExecutor(
   }
 
   HermesRuntime& hermesRuntimeRef = *hermesRuntime;
+  bool enableDebugger =
+      !jsinspector_modern::InspectorFlags::enableModernCDPRegistry &&
+      enableDebugger_;
   auto decoratedRuntime = std::make_shared<DecoratedRuntime>(
       std::move(hermesRuntime),
       hermesRuntimeRef,
       jsQueue,
-      enableDebugger_,
+      enableDebugger,
       debuggerName_);
 
   // So what do we have now?

packages/react-native/ReactCommon/jsinspector-modern/InspectorFlags.h

@@ -0,0 +1,24 @@
+/*
+ * 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
+
+namespace facebook::react::jsinspector_modern {
+
+/**
+ * A container for all inspector related feature flags. These will be set
+ * externally prior to React Native initialization.
+ */
+class InspectorFlags {
+ public:
+  /**
+   * Primary flag to enable the modern CDP backend.
+   */
+  static bool enableModernCDPRegistry;
+};
+
+} // namespace facebook::react::jsinspector_modern

packages/react-native/ReactCommon/jsinspector-modern/React-jsinspector.podspec

@@ -28,4 +28,6 @@ Pod::Spec.new do |s|
   s.source_files           = "*.{cpp,h}"
   s.header_dir             = 'jsinspector'
   s.pod_target_xcconfig    = { "CLANG_CXX_LANGUAGE_STANDARD" => "c++20" }
+
+  add_dependency(s, "React-nativeconfig")
 end

packages/react-native/ReactCommon/react/config/ReactNativeConfig.cpp

@@ -23,6 +23,9 @@ bool EmptyReactNativeConfig::getBool(const std::string& param) const {
   if (param == "react_fabric:enabled_layout_animations_ios") {
     return true;
   }
+  if (param == "react_native_devx:enable_modern_cdp_registry") {
+    return false;
+  }
   return false;
 }
 

packages/react-native/ReactCommon/react/runtime/hermes/HermesInstance.cpp

@@ -13,6 +13,7 @@
 #include <hermes/inspector-modern/chrome/Registration.h>
 #include <hermes/inspector/RuntimeAdapter.h>
 #include <jsi/decorator.h>
+#include <jsinspector-modern/InspectorFlags.h>
 #endif
 
 using namespace facebook::hermes;
@@ -141,10 +142,12 @@ std::unique_ptr<JSRuntime> HermesInstance::createJSRuntime(
       hermes::makeHermesRuntime(runtimeConfigBuilder.build());
 
 #ifdef HERMES_ENABLE_DEBUGGER
-  std::unique_ptr<DecoratedRuntime> decoratedRuntime =
-      std::make_unique<DecoratedRuntime>(
-          std::move(hermesRuntime), msgQueueThread);
-  return std::make_unique<JSIRuntimeHolder>(std::move(decoratedRuntime));
+  if (!jsinspector_modern::InspectorFlags::enableModernCDPRegistry) {
+    std::unique_ptr<DecoratedRuntime> decoratedRuntime =
+        std::make_unique<DecoratedRuntime>(
+            std::move(hermesRuntime), msgQueueThread);
+    return std::make_unique<JSIRuntimeHolder>(std::move(decoratedRuntime));
+  }
 #endif
 
   return std::make_unique<JSIRuntimeHolder>(std::move(hermesRuntime));