Register RCTHost with modern CDP backend (#42393)

Summary:
Changelog: [Internal][iOS] - Enable stub modern CDP backend in Bridgeless behind a feature flag

Minimally integrates the stub native CDP backend implementation (D50936932) into iOS Bridgeless.

This integration registers itself as a "Modern" target (D50967794, D50967795) to instruct `inspector-proxy` to disable its CDP hacks related to source map fetching, reloads, etc. This gives us a mostly-clean slate on which to develop and test native CDP functionality.

Pull Request resolved: https://github.com/facebook/react-native/pull/42393

Test Plan:
1. `js1 run`
2. Enable the modern CDP backend by grafting D52844391
3. Enable Bridgeless in RNTester by grafting D52910646
4. `buck2 install rntester-ios`
5. Dev Menu -> Open Debugger
6. Observe console message self-identifying the backend + iOS Bridgeless
7. Observe that the debugger stays connected when the app is reloaded (albeit without doing anything very interesting just yet)

{F1329876835}

Reviewed By: huntie

Differential Revision: D50936931

Pulled By: motiz88

fbshipit-source-id: ff8f919d0370266aea2916da349520bc76d690ab

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

@@ -12,6 +12,18 @@
 #include <optional>
 #include <string>
 
+#ifndef JSINSPECTOR_EXPORT
+#ifdef _MSC_VER
+#ifdef CREATE_SHARED_LIBRARY
+#define JSINSPECTOR_EXPORT __declspec(dllexport)
+#else
+#define JSINSPECTOR_EXPORT
+#endif // CREATE_SHARED_LIBRARY
+#else // _MSC_VER
+#define JSINSPECTOR_EXPORT __attribute__((visibility("default")))
+#endif // _MSC_VER
+#endif // !defined(JSINSPECTOR_EXPORT)
+
 namespace facebook::react::jsinspector_modern {
 
 /**
@@ -19,7 +31,7 @@ namespace facebook::react::jsinspector_modern {
  * "Host" in React Native's architecture - the entity that manages the
  * lifecycle of a React Instance.
  */
-class PageTarget {
+class JSINSPECTOR_EXPORT PageTarget {
  public:
   struct SessionMetadata {
     std::optional<std::string> integrationName;

packages/react-native/ReactCommon/react/runtime/CMakeLists.txt

@@ -35,4 +35,5 @@ target_link_libraries(
         jsi
         jsireact
         react_utils
+        jsinspector
 )

packages/react-native/ReactCommon/react/runtime/React-RuntimeCore.podspec

@@ -62,4 +62,5 @@ Pod::Spec.new do |s|
     s.dependency "React-jsc"
   end
 
+  s.dependency "React-jsinspector"
 end

packages/react-native/ReactCommon/react/runtime/platform/ios/React-RuntimeApple.podspec

@@ -65,6 +65,7 @@ Pod::Spec.new do |s|
   s.dependency "React-RuntimeCore"
   s.dependency "React-Mapbuffer"
   s.dependency "React-jserrorhandler"
+  s.dependency "React-jsinspector"
 
   if ENV["USE_HERMES"] == nil || ENV["USE_HERMES"] == "1"
     s.dependency "hermes-engine"

packages/react-native/ReactCommon/react/runtime/platform/ios/ReactCommon/RCTHost.mm

@@ -17,6 +17,10 @@
 #import <React/RCTMockDef.h>
 #import <React/RCTPerformanceLogger.h>
 #import <React/RCTReloadCommand.h>
+#import <jsinspector-modern/InspectorFlags.h>
+#import <jsinspector-modern/InspectorInterfaces.h>
+#import <jsinspector-modern/ReactCdp.h>
+#import <optional>
 
 RCT_MOCK_DEF(RCTHost, _RCTLogNativeInternal);
 #define _RCTLogNativeInternal RCT_MOCK_USE(RCTHost, _RCTLogNativeInternal)
@@ -47,6 +51,9 @@ using namespace facebook::react;
   std::vector<__weak RCTFabricSurface *> _attachedSurfaces;
 
   RCTModuleRegistry *_moduleRegistry;
+
+  std::unique_ptr<jsinspector_modern::PageTarget> _inspectorTarget;
+  std::optional<int> _inspectorPageId;
 }
 
 + (void)initialize
@@ -141,6 +148,28 @@ using namespace facebook::react;
 
 - (void)start
 {
+  auto &inspectorFlags = jsinspector_modern::InspectorFlags::getInstance();
+  if (inspectorFlags.getEnableModernCDPRegistry() && !_inspectorPageId.has_value()) {
+    _inspectorTarget = std::make_unique<jsinspector_modern::PageTarget>();
+    __weak RCTHost *weakSelf = self;
+    _inspectorPageId = facebook::react::jsinspector_modern::getInspectorInstance().addPage(
+        "React Native Bridgeless (Experimental)",
+        /* vm */ "",
+        [weakSelf](std::unique_ptr<facebook::react::jsinspector_modern::IRemoteConnection> remote)
+            -> std::unique_ptr<facebook::react::jsinspector_modern::ILocalConnection> {
+          RCTHost *strongSelf = weakSelf;
+          if (!strongSelf) {
+            // This can happen if we're about to be dealloc'd. Reject the connection.
+            return nullptr;
+          }
+          return strongSelf->_inspectorTarget->connect(
+              std::move(remote),
+              {
+                  .integrationName = "iOS Bridgeless (RCTHost)",
+              });
+        },
+        facebook::react::jsinspector_modern::InspectorPageType::Modern);
+  }
   if (_instance) {
     RCTLogWarn(
         @"RCTHost should not be creating a new instance if one already exists. This implies there is a bug with how/when this method is being called.");
@@ -228,6 +257,11 @@ using namespace facebook::react;
 
 - (void)dealloc
 {
+  if (_inspectorPageId.has_value()) {
+    facebook::react::jsinspector_modern::getInspectorInstance().removePage(*_inspectorPageId);
+    _inspectorPageId.reset();
+    _inspectorTarget.reset();
+  }
   [_instance invalidate];
 }