Add NotifyPassageEmbedderIdle Mojo method for BackgroundWebContents lifecycle (part 1.5) (#34054)

Add NotifyPassageEmbedderIdle Mojo method for BackgroundWebContents lifecycle

components/local_ai/core/local_ai.mojom

@@ -33,4 +33,8 @@ interface LocalAIService {
   // Creates the background WebContents if needed. If the factory is
   // not yet registered, the callback is deferred until it is.
   GetPassageEmbedder() => (pending_remote<PassageEmbedder>? embedder);
+
+  // Called by the renderer when all PassageEmbedder receivers have
+  // disconnected. The browser may close the BackgroundWebContents.
+  NotifyPassageEmbedderIdle();
 };

components/local_ai/core/local_ai_service.cc

@@ -56,19 +56,21 @@ void LocalAIService::GetPassageEmbedder(GetPassageEmbedderCallback callback) {
   }
 }
 
+void LocalAIService::NotifyPassageEmbedderIdle() {
+  DVLOG(3) << "LocalAIService: PassageEmbedder idle";
+  CloseBackgroundContents();
+}
+
 void LocalAIService::OnBackgroundContentsDestroyed(
     BackgroundWebContents::DestroyReason reason) {
   DVLOG(1) << "LocalAIService: Background contents destroyed";
-  factory_.reset();
-  CancelPendingCallbacks();
   CloseBackgroundContents();
 }
 
 void LocalAIService::Shutdown() {
   DVLOG(3) << "LocalAIService: Shutting down";
   receivers_.Clear();
-  factory_.reset();
-  CancelPendingCallbacks();
+  weak_ptr_factory_.InvalidateWeakPtrs();
   CloseBackgroundContents();
 }
 
@@ -83,6 +85,8 @@ void LocalAIService::MaybeCreateBackgroundContents() {
 
 void LocalAIService::CloseBackgroundContents() {
   DVLOG(3) << "LocalAIService: Closing background contents to free memory";
+  factory_.reset();
+  CancelPendingCallbacks();
   background_web_contents_.reset();
 }
 

components/local_ai/core/local_ai_service.h

@@ -52,6 +52,7 @@ class LocalAIService : public KeyedService,
   void RegisterPassageEmbedderFactory(
       mojo::PendingRemote<mojom::PassageEmbedderFactory> factory) override;
   void GetPassageEmbedder(GetPassageEmbedderCallback callback) override;
+  void NotifyPassageEmbedderIdle() override;
 
  private:
   // KeyedService:

components/local_ai/core/local_ai_service_unittest.cc

@@ -267,6 +267,24 @@ TEST_F(LocalAIServiceTest, DoubleShutdownIsIdempotent) {
   keyed_service->Shutdown();
 }
 
+TEST_F(LocalAIServiceTest, NotifyPassageEmbedderIdleClosesBackgroundContents) {
+  // Create background contents and register factory.
+  base::test::TestFuture<mojo::PendingRemote<mojom::PassageEmbedder>> future;
+  service_->GetPassageEmbedder(future.GetCallback());
+  RegisterFactory();
+  ASSERT_TRUE(future.Get().is_valid());
+  ASSERT_TRUE(last_created_web_contents_);
+
+  // Worker reports idle — should close background contents.
+  service_->NotifyPassageEmbedderIdle();
+  EXPECT_FALSE(last_created_web_contents_);
+
+  // Getting a new embedder should recreate background contents.
+  base::test::TestFuture<mojo::PendingRemote<mojom::PassageEmbedder>> future2;
+  service_->GetPassageEmbedder(future2.GetCallback());
+  EXPECT_TRUE(last_created_web_contents_);
+}
+
 TEST_F(LocalAIServiceTest, FactoryDisconnectCancelsPendingCallbacks) {
   // Queue a callback, register factory, then disconnect.
   base::test::TestFuture<mojo::PendingRemote<mojom::PassageEmbedder>>