Revert "Run Dart VM tasks on the engine's ConcurrentMessageLoop inste…

…ad the VM's separate thread pool. (flutter#29819)" (flutter#30332)

runtime/dart_isolate_unittests.cc

@@ -335,54 +335,7 @@ TEST_F(DartSecondaryIsolateTest, CanLaunchSecondaryIsolates) {
   // root isolate will be auto-shutdown
 }
 
-static thread_local bool is_engine_worker = false;
-
-TEST_F(DartSecondaryIsolateTest, VMTasksRunOnEngineThreads) {
-  AddNativeCallback("NotifyNative",
-                    CREATE_NATIVE_ENTRY(([this](Dart_NativeArguments args) {
-                      LatchCountDown();
-                    })));
-  AddNativeCallback("PassMessage",
-                    CREATE_NATIVE_ENTRY(([this](Dart_NativeArguments args) {
-                      // Child isolate is running on concurrent message loop
-                      // worker.
-                      ASSERT_TRUE(is_engine_worker);
-                      LatchCountDown();
-                    })));
-  auto settings = CreateSettingsForFixture();
-  settings.root_isolate_shutdown_callback = [this]() {
-    RootIsolateShutdownSignal();
-  };
-  settings.isolate_shutdown_callback = [this]() { ChildShutdownSignal(); };
-  auto vm_ref = DartVMRef::Create(settings);
-
-  auto loop = vm_ref->GetConcurrentMessageLoop();
-  fml::CountDownLatch latch(loop->GetWorkerCount());
-  vm_ref->GetConcurrentMessageLoop()->PostTaskToAllWorkers([&] {
-    is_engine_worker = true;
-    latch.CountDown();
-  });
-  latch.Wait();
-
-  auto thread = CreateNewThread();
-  TaskRunners task_runners(GetCurrentTestName(),  //
-                           thread,                //
-                           thread,                //
-                           thread,                //
-                           thread                 //
-  );
-  auto isolate = RunDartCodeInIsolate(vm_ref, settings, task_runners,
-                                      "testCanLaunchSecondaryIsolate", {},
-                                      GetDefaultKernelFilePath());
-  ASSERT_TRUE(isolate);
-  ASSERT_EQ(isolate->get()->GetPhase(), DartIsolate::Phase::Running);
-  ChildShutdownWait();  // wait for child isolate to shutdown first
-  ASSERT_FALSE(RootIsolateIsSignaled());
-  LatchWait();  // wait for last NotifyNative called by main isolate
-  // root isolate will be auto-shutdown
-}
-
-TEST_F(DartIsolateTest, CanRecieveArguments) {
+TEST_F(DartIsolateTest, CanReceiveArguments) {
   AddNativeCallback("NotifyNative",
                     CREATE_NATIVE_ENTRY(([this](Dart_NativeArguments args) {
                       ASSERT_TRUE(tonic::DartConverter<bool>::FromDart(

runtime/dart_vm.cc

@@ -170,14 +170,6 @@ Dart_Handle GetVMServiceAssetsArchiveCallback() {
 #endif
 }
 
-void PostTaskCallback(void* post_task_data,
-                      Dart_Task task,
-                      Dart_TaskData task_data) {
-  auto* dart_vm = reinterpret_cast<DartVM*>(post_task_data);
-  dart_vm->GetConcurrentWorkerTaskRunner()->PostTask(
-      [task] { Dart_RunTask(task); });
-}
-
 static const char kStdoutStreamId[] = "Stdout";
 static const char kStderrStreamId[] = "Stderr";
 
@@ -450,8 +442,6 @@ DartVM::DartVM(std::shared_ptr<const DartVMData> vm_data,
     params.thread_exit = ThreadExitCallback;
     params.get_service_assets = GetVMServiceAssetsArchiveCallback;
     params.entropy_source = dart::bin::GetEntropy;
-    params.post_task = PostTaskCallback;
-    params.post_task_data = this;
     DartVMInitializer::Initialize(&params);
     // Send the earliest available timestamp in the application lifecycle to
     // timeline. The difference between this timestamp and the time we render
@@ -486,10 +476,6 @@ DartVM::DartVM(std::shared_ptr<const DartVMData> vm_data,
     Dart_SetDartLibrarySourcesKernel(dart_library_sources->GetMapping(),
                                      dart_library_sources->GetSize());
   }
-
-  // Update thread names now that the Dart VM is initialized.
-  concurrent_message_loop_->PostTaskToAllWorkers(
-      [] { Dart_SetThreadName("FlutterConcurrentMessageLoopWorker"); });
 }
 
 DartVM::~DartVM() {