Ensure that the isolate shutdown callback occurs in an isolate scope.

runtime/dart_isolate.cc

@@ -477,6 +477,7 @@ bool DartIsolate::Shutdown() {
     // the isolate to shutdown as a parameter.
     FML_DCHECK(Dart_CurrentIsolate() == nullptr);
     Dart_EnterIsolate(vm_isolate);
+    shutdown_callbacks_.clear();
     Dart_ShutdownIsolate();
     FML_DCHECK(Dart_CurrentIsolate() == nullptr);
   }

runtime/dart_isolate_unittests.cc

@@ -46,4 +46,39 @@ TEST_F(DartIsolateTest, RootIsolateCreationAndShutdown) {
   ASSERT_TRUE(root_isolate->Shutdown());
 }
 
+TEST_F(DartIsolateTest, IsolateShutdownCallbackIsInIsolateScope) {
+  Settings settings = {};
+  settings.task_observer_add = [](intptr_t, fml::closure) {};
+  settings.task_observer_remove = [](intptr_t) {};
+  auto vm = DartVM::ForProcess(settings);
+  ASSERT_TRUE(vm);
+  TaskRunners task_runners(CURRENT_TEST_NAME,       //
+                           GetCurrentTaskRunner(),  //
+                           GetCurrentTaskRunner(),  //
+                           GetCurrentTaskRunner(),  //
+                           GetCurrentTaskRunner()   //
+  );
+  auto weak_isolate = DartIsolate::CreateRootIsolate(
+      vm.get(),                  // vm
+      vm->GetIsolateSnapshot(),  // isolate snapshot
+      vm->GetSharedSnapshot(),   // shared snapshot
+      std::move(task_runners),   // task runners
+      nullptr,                   // window
+      {},                        // resource context
+      nullptr,                   // unref qeueue
+      "main.dart",               // advisory uri
+      "main"                     // advisory entrypoint
+  );
+  auto root_isolate = weak_isolate.lock();
+  ASSERT_TRUE(root_isolate);
+  ASSERT_EQ(root_isolate->GetPhase(), DartIsolate::Phase::LibrariesSetup);
+  size_t destruction_callback_count = 0;
+  root_isolate->AddIsolateShutdownCallback([&destruction_callback_count]() {
+    ASSERT_NE(Dart_CurrentIsolate(), nullptr);
+    destruction_callback_count++;
+  });
+  ASSERT_TRUE(root_isolate->Shutdown());
+  ASSERT_EQ(destruction_callback_count, 1u);
+}
+
 }  // namespace blink