Fixed plumbing of the spawning isolate for Shell::Spawn.

runtime/runtime_controller.cc

@@ -406,7 +406,8 @@ bool RuntimeController::LaunchRootIsolate(
           dart_entrypoint,                                //
           dart_entrypoint_library,                        //
           std::move(isolate_configuration),               //
-          volatile_path_tracker_                          //
+          volatile_path_tracker_,                         //
+          spawning_isolate_.lock().get()                  //
           )
           .lock();
 
@@ -452,6 +453,17 @@ std::optional<uint32_t> RuntimeController::GetRootIsolateReturnCode() {
   return root_isolate_return_code_;
 }
 
+uint64_t RuntimeController::GetRootIsolateGroup() const {
+  auto isolate = root_isolate_.lock();
+  if (isolate) {
+    auto isolate_scope = tonic::DartIsolateScope(isolate->isolate());
+    Dart_IsolateGroup isolate_group = Dart_CurrentIsolateGroup();
+    return reinterpret_cast<uint64_t>(isolate_group);
+  } else {
+    return 0;
+  }
+}
+
 void RuntimeController::LoadDartDeferredLibrary(
     intptr_t loading_unit_id,
     std::unique_ptr<const fml::Mapping> snapshot_data,

runtime/runtime_controller.h

@@ -508,6 +508,14 @@ class RuntimeController : public PlatformConfigurationClient {
   ///
   std::optional<uint32_t> GetRootIsolateReturnCode();
 
+  //----------------------------------------------------------------------------
+  /// @brief      Get an identifier that represents the Dart isolate group the
+  ///             root isolate is in.
+  ///
+  /// @return     The root isolate isolate group identifier, zero if one can't
+  ///             be established.
+  uint64_t GetRootIsolateGroup() const;
+
   //--------------------------------------------------------------------------
   /// @brief      Loads the Dart shared library into the Dart VM. When the
   ///             Dart library is loaded successfully, the Dart future

shell/common/engine.h

@@ -886,6 +886,13 @@ class Engine final : public RuntimeDelegate,
                                     const std::string error_message,
                                     bool transient);
 
+  //--------------------------------------------------------------------------
+  /// @brief      Accessor for the RuntimeController.
+  ///
+  const RuntimeController* GetRuntimeController() const {
+    return runtime_controller_.get();
+  }
+
  private:
   Engine::Delegate& delegate_;
   const Settings settings_;

shell/common/shell_unittests.cc

@@ -2484,11 +2484,27 @@ TEST_F(ShellTest, Spawn) {
         ASSERT_NE(nullptr, spawn.get());
         ASSERT_TRUE(ValidateShell(spawn.get()));
 
-        PostSync(spawner->GetTaskRunners().GetUITaskRunner(), [&spawn] {
-          // Check second shell ran the second entrypoint.
-          ASSERT_EQ("testCanLaunchSecondaryIsolate",
-                    spawn->GetEngine()->GetLastEntrypoint());
-        });
+        PostSync(spawner->GetTaskRunners().GetUITaskRunner(),
+                 [&spawn, &spawner] {
+                   // Check second shell ran the second entrypoint.
+                   ASSERT_EQ("testCanLaunchSecondaryIsolate",
+                             spawn->GetEngine()->GetLastEntrypoint());
+
+                   // TODO(74520): Remove conditional once isolate groups are
+                   // supported by JIT.
+                   if (DartVM::IsRunningPrecompiledCode()) {
+                     ASSERT_NE(spawner->GetEngine()
+                                   ->GetRuntimeController()
+                                   ->GetRootIsolateGroup(),
+                               0u);
+                     ASSERT_EQ(spawner->GetEngine()
+                                   ->GetRuntimeController()
+                                   ->GetRootIsolateGroup(),
+                               spawn->GetEngine()
+                                   ->GetRuntimeController()
+                                   ->GetRootIsolateGroup());
+                   }
+                 });
 
         PostSync(
             spawner->GetTaskRunners().GetIOTaskRunner(), [&spawner, &spawn] {