Ensure root isolate create callback is invoked before the isolate is in the running phase.

common/settings.h

@@ -59,6 +59,8 @@ using MappingsCallback = std::function<Mappings(void)>;
 
 using FrameRasterizedCallback = std::function<void(const FrameTiming&)>;
 
+class DartIsolate;
+
 struct Settings {
   Settings();
 
@@ -169,7 +171,9 @@ struct Settings {
   TaskObserverRemove task_observer_remove;
   // The main isolate is current when this callback is made. This is a good spot
   // to perform native Dart bindings for libraries not built in.
-  fml::closure root_isolate_create_callback;
+  std::function<void(const DartIsolate&)> root_isolate_create_callback;
+  // TODO(68738): Update isolate callbacks in settings to accept an additional
+  // DartIsolate parameter.
   fml::closure isolate_create_callback;
   // The isolate is not current and may have already been destroyed when this
   // call is made.

runtime/dart_isolate.cc

@@ -148,21 +148,21 @@ std::weak_ptr<DartIsolate> DartIsolate::CreateRunningRootIsolate(
     return {};
   }
 
-  if (!isolate->RunFromLibrary(dart_entrypoint_library,               //
-                               dart_entrypoint,                       //
-                               settings.dart_entrypoint_args,         //
-                               settings.root_isolate_create_callback  //
+  if (settings.root_isolate_create_callback) {
+    // Isolate callbacks always occur in isolate scope and before user code has
+    // had a chance to run.
+    tonic::DartState::Scope scope(isolate.get());
+    settings.root_isolate_create_callback(*isolate.get());
+  }
+
+  if (!isolate->RunFromLibrary(dart_entrypoint_library,       //
+                               dart_entrypoint,               //
+                               settings.dart_entrypoint_args  //
                                )) {
     FML_LOG(ERROR) << "Could not run the run main Dart entrypoint.";
     return {};
   }
 
-  if (settings.root_isolate_create_callback) {
-    // Isolate callbacks always occur in isolate scope.
-    tonic::DartState::Scope scope(isolate.get());
-    settings.root_isolate_create_callback();
-  }
-
   if (settings.root_isolate_shutdown_callback) {
     isolate->AddIsolateShutdownCallback(
         settings.root_isolate_shutdown_callback);
@@ -617,8 +617,7 @@ bool DartIsolate::MarkIsolateRunnable() {
 
 bool DartIsolate::RunFromLibrary(std::optional<std::string> library_name,
                                  std::optional<std::string> entrypoint,
-                                 const std::vector<std::string>& args,
-                                 const fml::closure& on_run) {
+                                 const std::vector<std::string>& args) {
   TRACE_EVENT0("flutter", "DartIsolate::RunFromLibrary");
   if (phase_ != Phase::Ready) {
     return false;
@@ -644,9 +643,6 @@ bool DartIsolate::RunFromLibrary(std::optional<std::string> library_name,
 
   phase_ = Phase::Running;
 
-  if (on_run) {
-    on_run();
-  }
   return true;
 }
 

runtime/dart_isolate.h

@@ -342,20 +342,14 @@ class DartIsolate : public UIDartState {
   ///                           supplied entrypoint.
   /// @param[in]  entrypoint    The entrypoint in `library_name`
   /// @param[in]  args          A list of string arguments to the entrypoint.
-  /// @param[in]  on_run        A callback to run in isolate scope after the
-  ///                           main entrypoint has been invoked. There is no
-  ///                           isolate scope current on the thread once this
-  ///                           method returns.
   ///
   /// @return     If the isolate successfully transitioned to the running phase
   ///             and the main entrypoint was invoked.
   ///
   [[nodiscard]] bool RunFromLibrary(std::optional<std::string> library_name,
                                     std::optional<std::string> entrypoint,
-                                    const std::vector<std::string>& args,
-                                    const fml::closure& on_run = nullptr);
+                                    const std::vector<std::string>& args);
 
- public:
   //----------------------------------------------------------------------------
   /// @brief      Transition the isolate to the `Phase::Shutdown` phase. The
   ///             only thing left to do is to collect the isolate.

runtime/dart_isolate_unittests.cc

@@ -375,5 +375,32 @@ TEST_F(DartIsolateTest, CanCreateServiceIsolate) {
   ASSERT_TRUE(root_isolate->Shutdown());
 }
 
+TEST_F(DartIsolateTest,
+       RootIsolateCreateCallbackIsMadeOnceAndBeforeIsolateRunning) {
+  ASSERT_FALSE(DartVMRef::IsInstanceRunning());
+  auto settings = CreateSettingsForFixture();
+  size_t create_callback_count = 0u;
+  settings.root_isolate_create_callback =
+      [&create_callback_count](const auto& isolate) {
+        ASSERT_EQ(isolate.GetPhase(), DartIsolate::Phase::Ready);
+        create_callback_count++;
+        ASSERT_NE(::Dart_CurrentIsolate(), nullptr);
+      };
+  auto vm_ref = DartVMRef::Create(settings);
+  TaskRunners task_runners(GetCurrentTestName(),    //
+                           GetCurrentTaskRunner(),  //
+                           GetCurrentTaskRunner(),  //
+                           GetCurrentTaskRunner(),  //
+                           GetCurrentTaskRunner()   //
+  );
+  {
+    auto isolate = RunDartCodeInIsolate(vm_ref, settings, task_runners, "main",
+                                        {}, GetFixturesPath());
+    ASSERT_TRUE(isolate);
+    ASSERT_EQ(isolate->get()->GetPhase(), DartIsolate::Phase::Running);
+  }
+  ASSERT_EQ(create_callback_count, 1u);
+}
+
 }  // namespace testing
 }  // namespace flutter

shell/platform/embedder/embedder.cc

@@ -841,9 +841,8 @@ FlutterEngineResult FlutterEngineInitialize(size_t version,
   if (SAFE_ACCESS(args, root_isolate_create_callback, nullptr) != nullptr) {
     VoidCallback callback =
         SAFE_ACCESS(args, root_isolate_create_callback, nullptr);
-    settings.root_isolate_create_callback = [callback, user_data]() {
-      callback(user_data);
-    };
+    settings.root_isolate_create_callback =
+        [callback, user_data](const auto& isolate) { callback(user_data); };
   }
 
   flutter::PlatformViewEmbedder::UpdateSemanticsNodesCallback