[fuchsia] Cleanup unused method in dart:zircon handle (#27330)

shell/platform/fuchsia/dart-pkg/zircon/sdk_ext/handle.cc

@@ -16,29 +16,7 @@ namespace dart {
 
 IMPLEMENT_WRAPPERTYPEINFO(zircon, Handle);
 
-Handle::Handle(zx_handle_t handle) : handle_(handle) {
-  tonic::DartState* state = tonic::DartState::Current();
-  FML_DCHECK(state);
-  Dart_Handle zircon_lib = Dart_LookupLibrary(ToDart("dart:zircon"));
-  FML_DCHECK(!tonic::LogIfError(zircon_lib));
-
-  Dart_Handle on_wait_completer_type =
-      Dart_GetClass(zircon_lib, ToDart("_OnWaitCompleteClosure"));
-  FML_DCHECK(!tonic::LogIfError(on_wait_completer_type));
-  on_wait_completer_type_.Set(state, on_wait_completer_type);
-
-  Dart_Handle async_lib = Dart_LookupLibrary(ToDart("dart:async"));
-  FML_DCHECK(!tonic::LogIfError(async_lib));
-  async_lib_.Set(state, async_lib);
-
-  Dart_Handle closure_string = ToDart("_closure");
-  FML_DCHECK(!tonic::LogIfError(closure_string));
-  closure_string_.Set(state, closure_string);
-
-  Dart_Handle schedule_microtask_string = ToDart("scheduleMicrotask");
-  FML_DCHECK(!tonic::LogIfError(schedule_microtask_string));
-  schedule_microtask_string_.Set(state, schedule_microtask_string);
-}
+Handle::Handle(zx_handle_t handle) : handle_(handle) {}
 
 Handle::~Handle() {
   if (is_valid()) {
@@ -129,36 +107,6 @@ Dart_Handle Handle::Replace(uint32_t rights) {
   return ToDart(Create(out_handle));
 }
 
-void Handle::ScheduleCallback(tonic::DartPersistentValue callback,
-                              zx_status_t status,
-                              const zx_packet_signal_t* signal) {
-  auto state = callback.dart_state().lock();
-  FML_DCHECK(state);
-  tonic::DartState::Scope scope(state);
-
-  // Make a new _OnWaitCompleteClosure(callback, status, signal->observed).
-  FML_DCHECK(!callback.is_empty());
-  std::vector<Dart_Handle> constructor_args{callback.Release(), ToDart(status),
-                                            ToDart(signal->observed)};
-  Dart_Handle on_wait_complete_closure =
-      Dart_New(on_wait_completer_type_.Get(), Dart_Null(),
-               constructor_args.size(), constructor_args.data());
-  FML_DCHECK(!tonic::LogIfError(on_wait_complete_closure));
-
-  // The _callback field contains the thunk:
-  // () => callback(status, signal->observed)
-  Dart_Handle closure =
-      Dart_GetField(on_wait_complete_closure, closure_string_.Get());
-  FML_DCHECK(!tonic::LogIfError(closure));
-
-  // Put the thunk on the microtask queue by calling scheduleMicrotask().
-  std::vector<Dart_Handle> sm_args{closure};
-  Dart_Handle sm_result =
-      Dart_Invoke(async_lib_.Get(), schedule_microtask_string_.Get(),
-                  sm_args.size(), sm_args.data());
-  FML_DCHECK(!tonic::LogIfError(sm_result));
-}
-
 // clang-format: off
 
 #define FOR_EACH_STATIC_BINDING(V) V(Handle, CreateInvalid)

shell/platform/fuchsia/dart-pkg/zircon/sdk_ext/handle.h

@@ -74,10 +74,6 @@ class Handle : public fml::RefCountedThreadSafe<Handle>,
 
   Dart_Handle Replace(uint32_t rights);
 
-  void ScheduleCallback(tonic::DartPersistentValue callback,
-                        zx_status_t status,
-                        const zx_packet_signal_t* signal);
-
  private:
   explicit Handle(zx_handle_t handle);
 
@@ -89,13 +85,6 @@ class Handle : public fml::RefCountedThreadSafe<Handle>,
 
   std::vector<HandleWaiter*> waiters_;
 
-  // Some cached persistent handles to make running handle wait completers
-  // faster.
-  tonic::DartPersistentValue async_lib_;
-  tonic::DartPersistentValue closure_string_;
-  tonic::DartPersistentValue on_wait_completer_type_;
-  tonic::DartPersistentValue schedule_microtask_string_;
-
   // Cache koid. To guarantee proper cache invalidation, only one `Handle`
   // should own the `zx_handle_t` at a time and use of syscalls that invalidate
   // the handle should use `ReleaseHandle()`.

shell/platform/fuchsia/dart-pkg/zircon/sdk_ext/handle_disposition.h

@@ -58,10 +58,10 @@ class HandleDisposition : public fml::RefCountedThreadSafe<HandleDisposition>,
 
   void ReleaseDartWrappableReference() const override { Release(); }
 
-  zx_handle_op_t operation_;
-  fml::RefPtr<dart::Handle> handle_;
-  zx_obj_type_t type_;
-  zx_rights_t rights_;
+  const zx_handle_op_t operation_;
+  const fml::RefPtr<dart::Handle> handle_;
+  const zx_obj_type_t type_;
+  const zx_rights_t rights_;
   zx_status_t result_;
 };