Initialize Perfetto with the in-process backend on iOS (#59415)

Summary:
Pull Request resolved: #59415

`initializePerfetto()` registers Perfetto's system backend on every platform. iOS and the other Apple device platforms have no system tracing service, so the system producer never connects and keeps retrying in the background for the app's lifetime, and a tracer in the app that starts a session without naming a backend gets the system one and records nothing.

On those platforms, register the in-process backend instead. Other platforms, including macOS, are unchanged. React Native's own `ReactCxxPlatform/react/profiling/perfetto.cpp` already registers the in-process backend on every platform but Android; this change is narrower and keeps the system backend on macOS and other desktop platforms, where `traced` can run.

Changelog: [Internal]

Reviewed By: christophpurrer, javache

Differential Revision: D126071088

fbshipit-source-id: c1d9ccfa60ef66dbc4178635602bbd1a2dd79279

Author: potomak

packages/react-native/ReactCommon/reactperflogger/reactperflogger/ReactPerfetto.cpp

@@ -12,6 +12,10 @@
 #include <perfetto.h>
 #include <unordered_map>
 
+#ifdef __APPLE__
+#include <TargetConditionals.h>
+#endif
+
 #include "FuseboxPerfettoDataSource.h"
 #include "HermesPerfettoDataSource.h"
 #include "ReactPerfettoCategories.h"
@@ -26,7 +30,13 @@ void initializePerfetto() {
     // is only used in tracing build, large buffers are okay
     // for now.
     args.shmem_size_hint_kb = 20 * 1024;
+#if defined(__APPLE__) && TARGET_OS_IPHONE
+    // iOS and the other Apple device platforms have no system tracing
+    // service.
+    args.backends |= perfetto::kInProcessBackend;
+#else
     args.backends |= perfetto::kSystemBackend;
+#endif
     args.use_monotonic_clock = true;
     perfetto::Tracing::Initialize(args);
     TrackEvent::Register();