Reintroduce non-NetworkService code for shared workers

The code was removed because it was unused by Android Webview, but we still need it.

Reverts:
Worker: Remove non-NetworkService code for shared workers in content/renderer/worker/
Worker: Remove non-NetworkService code for shared workers in content/browser/worker_host/
Worker: Remove non-NetworkService code from WorkerScriptLoaderFactory

And fixes the code up to deal with conflicting later changes.

Change-Id: Ib7307e0e10c78127f138162f37e796deb1efef65
Reviewed-by: Jüri Valdmann <juri.valdmann@qt.io>

20 files changed, 428 insertions, 150 deletions

diff --git a/chromium/content/browser/worker_host/dedicated_worker_host.cc b/chromium/content/browser/worker_host/dedicated_worker_host.cc
index 6de307ce00a..c24c9749542 100644
--- a/chromium/content/browser/worker_host/dedicated_worker_host.cc
+++ b/chromium/content/browser/worker_host/dedicated_worker_host.cc
@@ -161,6 +161,8 @@ class DedicatedWorkerHost : public service_manager::mojom::InterfaceProvider {
   // Called from WorkerScriptFetchInitiator. Continues starting the dedicated
   // worker in the renderer process.
   //
+  // |main_script_loader_factory| is not used when NetworkService is enabled.
+  //
   // |main_script_load_params| is sent to the renderer process and to be used to
   // load the dedicated worker main script pre-requested by the browser process.
   //
@@ -174,6 +176,7 @@ class DedicatedWorkerHost : public service_manager::mojom::InterfaceProvider {
   // a ServiceWorker object about the controller is prepared, it is registered
   // to |controller_service_worker_object_host|.
   void DidStartScriptLoad(
+      network::mojom::URLLoaderFactoryPtr main_script_loader_factory,
       std::unique_ptr<blink::URLLoaderFactoryBundleInfo>
           subresource_loader_factories,
       blink::mojom::WorkerMainScriptLoadParamsPtr main_script_load_params,
@@ -183,6 +186,8 @@ class DedicatedWorkerHost : public service_manager::mojom::InterfaceProvider {
       bool success) {
     DCHECK_CURRENTLY_ON(BrowserThread::UI);
     DCHECK(blink::features::IsPlzDedicatedWorkerEnabled());
+    // |main_script_loader_factory| is not used when NetworkService is enabled.
+    DCHECK(!main_script_loader_factory);
 
     if (!success) {
       client_->OnScriptLoadStartFailed();
diff --git a/chromium/content/browser/worker_host/mock_shared_worker.cc b/chromium/content/browser/worker_host/mock_shared_worker.cc
index c452b2f99c8..3b027003c6e 100644
--- a/chromium/content/browser/worker_host/mock_shared_worker.cc
+++ b/chromium/content/browser/worker_host/mock_shared_worker.cc
@@ -107,6 +107,7 @@ void MockSharedWorkerFactory::CreateSharedWorker(
     blink::mojom::ServiceWorkerProviderInfoForClientPtr
         service_worker_provider_info,
     const base::Optional<base::UnguessableToken>& appcache_host_id,
+    network::mojom::URLLoaderFactoryPtr main_script_loader_factory,
     blink::mojom::WorkerMainScriptLoadParamsPtr main_script_load_params,
     std::unique_ptr<blink::URLLoaderFactoryBundleInfo>
         subresource_loader_factories,
diff --git a/chromium/content/browser/worker_host/mock_shared_worker.h b/chromium/content/browser/worker_host/mock_shared_worker.h
index d10ae02d4ad..672ab44645a 100644
--- a/chromium/content/browser/worker_host/mock_shared_worker.h
+++ b/chromium/content/browser/worker_host/mock_shared_worker.h
@@ -82,6 +82,7 @@ class MockSharedWorkerFactory : public blink::mojom::SharedWorkerFactory {
       blink::mojom::ServiceWorkerProviderInfoForClientPtr
           service_worker_provider_info,
       const base::Optional<base::UnguessableToken>& appcache_host_id,
+      network::mojom::URLLoaderFactoryPtr main_script_loader_factory,
       blink::mojom::WorkerMainScriptLoadParamsPtr main_script_load_params,
       std::unique_ptr<blink::URLLoaderFactoryBundleInfo>
           subresource_loader_factories,
diff --git a/chromium/content/browser/worker_host/shared_worker_host.cc b/chromium/content/browser/worker_host/shared_worker_host.cc
index c11c026212e..8243f55e2fd 100644
--- a/chromium/content/browser/worker_host/shared_worker_host.cc
+++ b/chromium/content/browser/worker_host/shared_worker_host.cc
@@ -118,7 +118,6 @@ SharedWorkerHost::SharedWorkerHost(
       worker_process_id_(worker_process_id),
       next_connection_request_id_(1),
       interface_provider_binding_(this) {
-  DCHECK(base::FeatureList::IsEnabled(network::features::kNetworkService));
   DCHECK(instance_);
   // Set up the worker interface request. This is needed first in either
   // AddClient() or Start(). AddClient() can sometimes be called before Start()
@@ -167,6 +166,7 @@ void SharedWorkerHost::SetNetworkFactoryForTesting(
 
 void SharedWorkerHost::Start(
     blink::mojom::SharedWorkerFactoryPtr factory,
+    network::mojom::URLLoaderFactoryPtr main_script_loader_factory,
     blink::mojom::WorkerMainScriptLoadParamsPtr main_script_load_params,
     std::unique_ptr<blink::URLLoaderFactoryBundleInfo>
         subresource_loader_factories,
@@ -174,12 +174,27 @@ void SharedWorkerHost::Start(
     base::WeakPtr<ServiceWorkerObjectHost>
         controller_service_worker_object_host) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  DCHECK(main_script_load_params);
-  DCHECK(subresource_loader_factories);
-  DCHECK(!subresource_loader_factories->pending_default_factory());
-
   AdvanceTo(Phase::kStarted);
 
+#if DCHECK_IS_ON()
+  // Verify the combination of the given args based on the flags. See the
+  // function comment for details.
+  DCHECK(subresource_loader_factories);
+  if (base::FeatureList::IsEnabled(network::features::kNetworkService)) {
+    // NetworkService (PlzWorker):
+    DCHECK(!main_script_loader_factory);
+    DCHECK(main_script_load_params);
+    DCHECK(!subresource_loader_factories->pending_default_factory());
+  } else {
+    // non-NetworkService:
+    DCHECK(main_script_loader_factory);
+    DCHECK(!main_script_load_params);
+    DCHECK(subresource_loader_factories->pending_default_factory());
+    DCHECK(!controller);
+    DCHECK(!controller_service_worker_object_host);
+  }
+#endif  // DCHECK_IS_ON()
+
   blink::mojom::SharedWorkerInfoPtr info(blink::mojom::SharedWorkerInfo::New(
       instance_->url(), instance_->name(), instance_->content_security_policy(),
       instance_->content_security_policy_type(),
@@ -220,20 +235,29 @@ void SharedWorkerHost::Start(
       mojo::MakeRequest(&interface_provider)));
 
   // Set the default factory to the bundle for subresource loading to pass to
-  // the renderer.
-  mojo::PendingRemote<network::mojom::URLLoaderFactory> pending_default_factory;
-  CreateNetworkFactory(
-      pending_default_factory.InitWithNewPipeAndPassReceiver());
-  subresource_loader_factories->pending_default_factory() =
-      std::move(pending_default_factory);
+  // the renderer when NetworkService is on. When NetworkService is off, the
+  // default factory is already provided by
+  // WorkerScriptFetchInitiator::CreateFactoryBundle().
+  if (base::FeatureList::IsEnabled(network::features::kNetworkService)) {
+    mojo::PendingRemote<network::mojom::URLLoaderFactory> pending_default_factory;
+    CreateNetworkFactory(
+        pending_default_factory.InitWithNewPipeAndPassReceiver());
+    subresource_loader_factories->pending_default_factory() =
+        std::move(pending_default_factory);
+  }
 
+  // NetworkService (PlzWorker):
   // Prepare the controller service worker info to pass to the renderer.
+  // |controller| is only provided if NetworkService is enabled. In the
+  // non-NetworkService case, the controller is sent in SetController IPCs
+  // during the request for the shared worker script.
   // |object_info| can be nullptr when the service worker context or the service
   // worker version is gone during shared worker startup.
   blink::mojom::ServiceWorkerObjectAssociatedPtrInfo
       service_worker_remote_object;
   blink::mojom::ServiceWorkerState service_worker_sent_state;
   if (controller && controller->object_info) {
+    DCHECK(base::FeatureList::IsEnabled(network::features::kNetworkService));
     controller->object_info->request =
         mojo::MakeRequest(&service_worker_remote_object);
     service_worker_sent_state = controller->object_info->state;
@@ -248,16 +272,18 @@ void SharedWorkerHost::Start(
       appcache_handle_
           ? base::make_optional(appcache_handle_->appcache_host_id())
           : base::nullopt,
-      std::move(main_script_load_params),
+      std::move(main_script_loader_factory), std::move(main_script_load_params),
       std::move(subresource_loader_factories), std::move(controller),
       std::move(host), std::move(worker_request_),
       std::move(interface_provider));
 
+  // NetworkService (PlzWorker):
   // |service_worker_remote_object| is an associated interface ptr, so calls
   // can't be made on it until its request endpoint is sent. Now that the
   // request endpoint was sent, it can be used, so add it to
   // ServiceWorkerObjectHost.
   if (service_worker_remote_object.is_valid()) {
+    DCHECK(base::FeatureList::IsEnabled(network::features::kNetworkService));
     base::PostTaskWithTraits(
         FROM_HERE, {BrowserThread::IO},
         base::BindOnce(
diff --git a/chromium/content/browser/worker_host/shared_worker_host.h b/chromium/content/browser/worker_host/shared_worker_host.h
index 9395da716da..87c552bad23 100644
--- a/chromium/content/browser/worker_host/shared_worker_host.h
+++ b/chromium/content/browser/worker_host/shared_worker_host.h
@@ -70,6 +70,11 @@ class CONTENT_EXPORT SharedWorkerHost
 
   // Starts the SharedWorker in the renderer process.
   //
+  // |main_script_loader_factory| is sent to the renderer process and is to be
+  // used to request the shared worker's main script. This is null when
+  // NetworkService is enabled in favor of |main_script_load_params|.
+  //
+  // NetworkService (PlzWorker):
   // |main_script_load_params| is sent to the renderer process and to be used to
   // load the shared worker main script pre-requested by the browser process.
   //
@@ -78,11 +83,16 @@ class CONTENT_EXPORT SharedWorkerHost
   // shared worker to load chrome-extension:// URLs which the renderer's default
   // loader factory can't load.
   //
+  // NetworkService (PlzWorker):
   // |controller| contains information about the service worker controller. Once
   // a ServiceWorker object about the controller is prepared, it is registered
-  // to |controller_service_worker_object_host|.
+  // to |controller_service_worker_object_host|. These can be non-null only when
+  // NetworkService is enabled.
+  // When NetworkService is disabled, the service worker controller is sent via
+  // ServiceWorkerContainer#SetController.
   void Start(
       blink::mojom::SharedWorkerFactoryPtr factory,
+      network::mojom::URLLoaderFactoryPtr main_script_loader_factory,
       blink::mojom::WorkerMainScriptLoadParamsPtr main_script_load_params,
       std::unique_ptr<blink::URLLoaderFactoryBundleInfo>
           subresource_loader_factories,
@@ -197,6 +207,7 @@ class CONTENT_EXPORT SharedWorkerHost
   mojo::Binding<service_manager::mojom::InterfaceProvider>
       interface_provider_binding_;
 
+  // NetworkService:
   // The handle owns the precreated AppCacheHost until it's claimed by the
   // renderer after main script loading finishes.
   std::unique_ptr<AppCacheNavigationHandle> appcache_handle_;
diff --git a/chromium/content/browser/worker_host/shared_worker_service_impl.cc b/chromium/content/browser/worker_host/shared_worker_service_impl.cc
index 54f9a69434e..a1117afa541 100644
--- a/chromium/content/browser/worker_host/shared_worker_service_impl.cc
+++ b/chromium/content/browser/worker_host/shared_worker_service_impl.cc
@@ -208,7 +208,6 @@ void SharedWorkerServiceImpl::CreateWorker(
     const blink::MessagePortChannel& message_port,
     scoped_refptr<network::SharedURLLoaderFactory> blob_url_loader_factory) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  DCHECK(base::FeatureList::IsEnabled(network::features::kNetworkService));
   DCHECK(!IsShuttingDown(RenderProcessHost::FromID(client_process_id)));
   DCHECK(!blob_url_loader_factory || instance->url().SchemeIsBlob());
 
@@ -221,11 +220,16 @@ void SharedWorkerServiceImpl::CreateWorker(
   auto weak_host = host->AsWeakPtr();
   worker_hosts_.insert(std::move(host));
 
-  auto appcache_handle = std::make_unique<AppCacheNavigationHandle>(
-      appcache_service_.get(), weak_host->worker_process_id());
-  AppCacheNavigationHandleCore* appcache_handle_core = appcache_handle_core =
-      appcache_handle->core();
-  weak_host->SetAppCacheHandle(std::move(appcache_handle));
+  // NetworkService (PlzWorker):
+  // An appcache interceptor is available only when the network service is
+  // enabled.
+  AppCacheNavigationHandleCore* appcache_handle_core = nullptr;
+  if (base::FeatureList::IsEnabled(network::features::kNetworkService)) {
+    auto appcache_handle = std::make_unique<AppCacheNavigationHandle>(
+        appcache_service_.get(), weak_host->worker_process_id());
+    appcache_handle_core = appcache_handle->core();
+    weak_host->SetAppCacheHandle(std::move(appcache_handle));
+  }
 
   auto service_worker_handle = std::make_unique<ServiceWorkerNavigationHandle>(
       storage_partition_->GetServiceWorkerContext());
@@ -260,6 +264,7 @@ void SharedWorkerServiceImpl::DidCreateScriptLoader(
     int process_id,
     int frame_id,
     const blink::MessagePortChannel& message_port,
+    network::mojom::URLLoaderFactoryPtr main_script_loader_factory,
     std::unique_ptr<blink::URLLoaderFactoryBundleInfo>
         subresource_loader_factories,
     blink::mojom::WorkerMainScriptLoadParamsPtr main_script_load_params,
@@ -269,9 +274,11 @@ void SharedWorkerServiceImpl::DidCreateScriptLoader(
     bool success) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
+  // NetworkService (PlzWorker):
   // If the script fetcher fails to load shared worker's main script, notify the
   // client of the failure and abort shared worker startup.
   if (!success) {
+    DCHECK(base::FeatureList::IsEnabled(network::features::kNetworkService));
     client->OnScriptLoadFailed();
     return;
   }
@@ -281,6 +288,7 @@ void SharedWorkerServiceImpl::DidCreateScriptLoader(
 
   StartWorker(std::move(instance), std::move(host), std::move(client),
               process_id, frame_id, message_port,
+              std::move(main_script_loader_factory),
               std::move(subresource_loader_factories),
               std::move(main_script_load_params), std::move(controller),
               std::move(controller_service_worker_object_host));
@@ -293,6 +301,7 @@ void SharedWorkerServiceImpl::StartWorker(
     int client_process_id,
     int frame_id,
     const blink::MessagePortChannel& message_port,
+    network::mojom::URLLoaderFactoryPtr main_script_loader_factory,
     std::unique_ptr<blink::URLLoaderFactoryBundleInfo>
         subresource_loader_factories,
     blink::mojom::WorkerMainScriptLoadParamsPtr main_script_load_params,
@@ -321,7 +330,9 @@ void SharedWorkerServiceImpl::StartWorker(
   blink::mojom::SharedWorkerFactoryPtr factory;
   BindInterface(worker_process_host, &factory);
 
-  host->Start(std::move(factory), std::move(main_script_load_params),
+  host->Start(std::move(factory),
+              std::move(main_script_loader_factory),
+              std::move(main_script_load_params),
               std::move(subresource_loader_factories), std::move(controller),
               std::move(controller_service_worker_object_host));
   host->AddClient(std::move(client), client_process_id, frame_id, message_port);
diff --git a/chromium/content/browser/worker_host/shared_worker_service_impl.h b/chromium/content/browser/worker_host/shared_worker_service_impl.h
index 553f1de7fa2..f7ee7ea0e92 100644
--- a/chromium/content/browser/worker_host/shared_worker_service_impl.h
+++ b/chromium/content/browser/worker_host/shared_worker_service_impl.h
@@ -97,6 +97,7 @@ class CONTENT_EXPORT SharedWorkerServiceImpl : public SharedWorkerService {
       int client_process_id,
       int frame_id,
       const blink::MessagePortChannel& message_port,
+      network::mojom::URLLoaderFactoryPtr main_script_loader_factory,
       std::unique_ptr<blink::URLLoaderFactoryBundleInfo>
           subresource_loader_factories,
       blink::mojom::WorkerMainScriptLoadParamsPtr main_script_load_params,
@@ -111,6 +112,7 @@ class CONTENT_EXPORT SharedWorkerServiceImpl : public SharedWorkerService {
       int client_process_id,
       int frame_id,
       const blink::MessagePortChannel& message_port,
+      network::mojom::URLLoaderFactoryPtr main_script_loader_factory,
       std::unique_ptr<blink::URLLoaderFactoryBundleInfo>
           subresource_loader_factories,
       blink::mojom::WorkerMainScriptLoadParamsPtr main_script_load_params,
diff --git a/chromium/content/browser/worker_host/shared_worker_service_impl_unittest.cc b/chromium/content/browser/worker_host/shared_worker_service_impl_unittest.cc
index 44eea2c414e..99b6ad05529 100644
--- a/chromium/content/browser/worker_host/shared_worker_service_impl_unittest.cc
+++ b/chromium/content/browser/worker_host/shared_worker_service_impl_unittest.cc
@@ -154,14 +154,20 @@ class SharedWorkerServiceImplTest : public RenderViewHostImplTestHarness {
     RenderProcessHostImpl::set_render_process_host_factory_for_testing(
         render_process_host_factory_.get());
 
-    fake_url_loader_factory_ = std::make_unique<FakeNetworkURLLoaderFactory>();
-    url_loader_factory_wrapper_ =
-        base::MakeRefCounted<network::WeakWrapperSharedURLLoaderFactory>(
-            fake_url_loader_factory_.get());
-    static_cast<SharedWorkerServiceImpl*>(
-        BrowserContext::GetDefaultStoragePartition(browser_context_.get())
-            ->GetSharedWorkerService())
-        ->SetURLLoaderFactoryForTesting(url_loader_factory_wrapper_);
+    if (base::FeatureList::IsEnabled(network::features::kNetworkService)) {
+      fake_url_loader_factory_ =
+          std::make_unique<FakeNetworkURLLoaderFactory>();
+      url_loader_factory_wrapper_ =
+          base::MakeRefCounted<network::WeakWrapperSharedURLLoaderFactory>(
+              fake_url_loader_factory_.get());
+      static_cast<SharedWorkerServiceImpl*>(
+          BrowserContext::GetDefaultStoragePartition(browser_context_.get())
+              ->GetSharedWorkerService())
+          ->SetURLLoaderFactoryForTesting(url_loader_factory_wrapper_);
+    } else {
+      url_loader_factory_ =
+          std::make_unique<NotImplementedNetworkURLLoaderFactory>();
+    }
   }
 
   void TearDown() override {
@@ -184,6 +190,7 @@ class SharedWorkerServiceImplTest : public RenderViewHostImplTestHarness {
   int factory_request_callback_process_id_ = ChildProcessHost::kInvalidUniqueID;
 
   std::unique_ptr<MockRenderProcessHostFactory> render_process_host_factory_;
+  std::unique_ptr<NotImplementedNetworkURLLoaderFactory> url_loader_factory_;
 
   std::unique_ptr<FakeNetworkURLLoaderFactory> fake_url_loader_factory_;
   scoped_refptr<network::WeakWrapperSharedURLLoaderFactory>
@@ -203,6 +210,8 @@ TEST_F(SharedWorkerServiceImplTest, BasicTest) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   MockSharedWorkerClient client;
   MessagePortChannel local_port;
@@ -277,6 +286,8 @@ TEST_F(SharedWorkerServiceImplTest, TwoRendererTest) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id0));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host0->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   MockSharedWorkerClient client0;
   MessagePortChannel local_port0;
@@ -346,6 +357,8 @@ TEST_F(SharedWorkerServiceImplTest, TwoRendererTest) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id1));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host1->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   MockSharedWorkerClient client1;
   MessagePortChannel local_port1;
@@ -409,6 +422,8 @@ TEST_F(SharedWorkerServiceImplTest, CreateWorkerTest_NormalCase) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id0));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host0->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   // The second renderer host.
   std::unique_ptr<TestWebContents> web_contents1 =
@@ -484,6 +499,8 @@ TEST_F(SharedWorkerServiceImplTest, CreateWorkerTest_NormalCase_URLMismatch) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id0));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host0->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   // The second renderer host.
   std::unique_ptr<TestWebContents> web_contents1 =
@@ -495,6 +512,8 @@ TEST_F(SharedWorkerServiceImplTest, CreateWorkerTest_NormalCase_URLMismatch) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id1));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host1->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   // First client, creates worker.
 
@@ -571,6 +590,8 @@ TEST_F(SharedWorkerServiceImplTest, CreateWorkerTest_NormalCase_NameMismatch) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id0));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host0->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   // The second renderer host.
   std::unique_ptr<TestWebContents> web_contents1 =
@@ -582,6 +603,8 @@ TEST_F(SharedWorkerServiceImplTest, CreateWorkerTest_NormalCase_NameMismatch) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id1));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host1->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   // First client, creates worker.
 
@@ -657,6 +680,8 @@ TEST_F(SharedWorkerServiceImplTest, CreateWorkerTest_PendingCase) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id0));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host0->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   // The second renderer host.
   std::unique_ptr<TestWebContents> web_contents1 =
@@ -668,6 +693,8 @@ TEST_F(SharedWorkerServiceImplTest, CreateWorkerTest_PendingCase) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id1));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host1->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   // First client and second client are created before the worker starts.
 
@@ -734,6 +761,8 @@ TEST_F(SharedWorkerServiceImplTest, CreateWorkerTest_PendingCase_URLMismatch) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), renderer_host0->GetID()));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host0->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   // The second renderer host.
   std::unique_ptr<TestWebContents> web_contents1 =
@@ -744,6 +773,8 @@ TEST_F(SharedWorkerServiceImplTest, CreateWorkerTest_PendingCase_URLMismatch) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), renderer_host1->GetID()));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host1->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   // First client and second client are created before the workers start.
 
@@ -824,6 +855,8 @@ TEST_F(SharedWorkerServiceImplTest, CreateWorkerTest_PendingCase_NameMismatch) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id0));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host0->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   // The second renderer host.
   std::unique_ptr<TestWebContents> web_contents1 =
@@ -835,6 +868,8 @@ TEST_F(SharedWorkerServiceImplTest, CreateWorkerTest_PendingCase_NameMismatch) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id1));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host1->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   // First client and second client are created before the workers start.
 
@@ -915,6 +950,8 @@ TEST_F(SharedWorkerServiceImplTest, CreateWorkerRaceTest) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id0));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host0->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   std::unique_ptr<TestWebContents> web_contents1 =
       CreateWebContents(GURL("http://example.com/"));
@@ -925,6 +962,8 @@ TEST_F(SharedWorkerServiceImplTest, CreateWorkerRaceTest) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id1));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host1->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   std::unique_ptr<TestWebContents> web_contents2 =
       CreateWebContents(GURL("http://example.com/"));
@@ -935,6 +974,8 @@ TEST_F(SharedWorkerServiceImplTest, CreateWorkerRaceTest) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id2));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host2->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   MockSharedWorkerClient client0;
   MessagePortChannel local_port0;
@@ -1027,6 +1068,8 @@ TEST_F(SharedWorkerServiceImplTest, CreateWorkerRaceTest2) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id0));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host0->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   std::unique_ptr<TestWebContents> web_contents1 =
       CreateWebContents(GURL("http://example.com/"));
@@ -1037,6 +1080,8 @@ TEST_F(SharedWorkerServiceImplTest, CreateWorkerRaceTest2) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id1));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host1->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   std::unique_ptr<TestWebContents> web_contents2 =
       CreateWebContents(GURL("http://example.com/"));
@@ -1047,6 +1092,8 @@ TEST_F(SharedWorkerServiceImplTest, CreateWorkerRaceTest2) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id2));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host2->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   MockSharedWorkerClient client0;
   MessagePortChannel local_port0;
@@ -1123,6 +1170,8 @@ TEST_F(SharedWorkerServiceImplTest, CreateWorkerRaceTest3) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id0));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host0->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   // The second renderer host.
   std::unique_ptr<TestWebContents> web_contents1 =
@@ -1134,6 +1183,8 @@ TEST_F(SharedWorkerServiceImplTest, CreateWorkerRaceTest3) {
       blink::mojom::SharedWorkerFactory::Name_,
       base::BindRepeating(&SharedWorkerServiceImplTest::BindSharedWorkerFactory,
                           base::Unretained(this), process_id1));
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService))
+    renderer_host1->OverrideURLLoaderFactory(url_loader_factory_.get());
 
   // Both clients try to connect/create a worker.
 
diff --git a/chromium/content/browser/worker_host/worker_browsertest.cc b/chromium/content/browser/worker_host/worker_browsertest.cc
index 0ebffbf24c5..d021ad2ebb4 100644
--- a/chromium/content/browser/worker_host/worker_browsertest.cc
+++ b/chromium/content/browser/worker_host/worker_browsertest.cc
@@ -36,6 +36,7 @@
 #include "net/test/embedded_test_server/embedded_test_server.h"
 #include "net/test/spawned_test_server/spawned_test_server.h"
 #include "net/test/test_data_directory.h"
+#include "services/network/public/cpp/features.h"
 #include "url/gurl.h"
 
 namespace content {
@@ -276,7 +277,12 @@ IN_PROC_BROWSER_TEST_F(WorkerTest,
 
 // Tests the value of |request_initiator| for shared worker resources.
 IN_PROC_BROWSER_TEST_F(WorkerTest, VerifyInitiatorSharedWorker) {
-  if (!SupportsSharedWorker())
+  // TODO(cammie): Remove the condition that network service must be
+  // enabled once it is enabled on all platforms?
+  // The main body of the test won't currently work unless network service
+  // is enabled (e.g. not on cast-shell-linux as of 2019/04).
+  if (!SupportsSharedWorker() ||
+      !base::FeatureList::IsEnabled(network::features::kNetworkService))
     return;
 
   const GURL start_url(embedded_test_server()->GetURL("/frame_tree/top.html"));
diff --git a/chromium/content/browser/worker_host/worker_script_fetch_initiator.cc b/chromium/content/browser/worker_host/worker_script_fetch_initiator.cc
index f5602a49c09..48d74986947 100644
--- a/chromium/content/browser/worker_host/worker_script_fetch_initiator.cc
+++ b/chromium/content/browser/worker_host/worker_script_fetch_initiator.cc
@@ -37,6 +37,7 @@
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/content_browser_client.h"
 #include "content/public/browser/render_frame_host.h"
+#include "content/public/browser/render_process_host.h"
 #include "content/public/browser/resource_context.h"
 #include "content/public/browser/shared_cors_origin_access_list.h"
 #include "content/public/common/content_features.h"
@@ -90,7 +91,6 @@ void WorkerScriptFetchInitiator::Start(
     const std::string& storage_domain,
     CompletionCallback callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  DCHECK(base::FeatureList::IsEnabled(network::features::kNetworkService));
   DCHECK(storage_partition);
   DCHECK(resource_type == ResourceType::kWorker ||
          resource_type == ResourceType::kSharedWorker)
@@ -124,67 +124,70 @@ void WorkerScriptFetchInitiator::Start(
           worker_process_id, storage_partition, storage_domain,
           constructor_uses_file_url, filesystem_url_support);
 
+  // NetworkService (PlzWorker):
   // Create a resource request for initiating worker script fetch from the
   // browser process.
   std::unique_ptr<network::ResourceRequest> resource_request;
-
-  // Determine the referrer for the worker script request based on the spec.
-  // https://w3c.github.io/webappsec-referrer-policy/#determine-requests-referrer
-  Referrer sanitized_referrer = Referrer::SanitizeForRequest(
-      script_url,
-      Referrer(outside_fetch_client_settings_object->outgoing_referrer,
-               outside_fetch_client_settings_object->referrer_policy));
-
-  resource_request = std::make_unique<network::ResourceRequest>();
-  resource_request->url = script_url;
-  resource_request->site_for_cookies = script_url;
-  resource_request->request_initiator = request_initiator;
-  resource_request->referrer = sanitized_referrer.url,
-  resource_request->referrer_policy = Referrer::ReferrerPolicyForUrlRequest(
-      outside_fetch_client_settings_object->referrer_policy);
-  resource_request->resource_type = static_cast<int>(resource_type);
-
-  // For a classic worker script request:
-  // https://html.spec.whatwg.org/C/#fetch-a-classic-worker-script
-  // Step 1: "Let request be a new request whose ..., mode is "same-origin",
-  // ..."
-  //
-  // For a module worker script request:
-  // https://html.spec.whatwg.org/C/#fetch-a-single-module-script
-  // Step 6: "If destination is "worker" or "sharedworker" and the top-level
-  // module fetch flag is set, then set request's mode to "same-origin"."
-  resource_request->mode = network::mojom::RequestMode::kSameOrigin;
-
-  // When the credentials mode is "omit", clear |allow_credentials| and set
-  // load flags to disable sending credentials according to the comments in
-  // CorsURLLoaderFactory::IsSane().
-  // TODO(https://crbug.com/799935): Unify |LOAD_DO_NOT_*| into
-  // |allow_credentials|.
-  resource_request->credentials_mode = credentials_mode;
-  if (credentials_mode == network::mojom::CredentialsMode::kOmit) {
-    resource_request->allow_credentials = false;
-    const auto load_flags_pattern = net::LOAD_DO_NOT_SAVE_COOKIES |
-                                    net::LOAD_DO_NOT_SEND_COOKIES |
-                                    net::LOAD_DO_NOT_SEND_AUTH_DATA;
-    resource_request->load_flags |= load_flags_pattern;
-  }
-
-  switch (resource_type) {
-    case ResourceType::kWorker:
-      resource_request->fetch_request_context_type =
-          static_cast<int>(blink::mojom::RequestContextType::WORKER);
-      break;
-    case ResourceType::kSharedWorker:
-      resource_request->fetch_request_context_type =
-          static_cast<int>(blink::mojom::RequestContextType::SHARED_WORKER);
-      break;
-    default:
-      NOTREACHED() << static_cast<int>(resource_type);
-      break;
+  if (base::FeatureList::IsEnabled(network::features::kNetworkService)) {
+    // Determine the referrer for the worker script request based on the spec.
+    // https://w3c.github.io/webappsec-referrer-policy/#determine-requests-referrer
+    Referrer sanitized_referrer = Referrer::SanitizeForRequest(
+        script_url,
+        Referrer(outside_fetch_client_settings_object->outgoing_referrer,
+                 outside_fetch_client_settings_object->referrer_policy));
+
+
+    resource_request = std::make_unique<network::ResourceRequest>();
+    resource_request->url = script_url;
+    resource_request->site_for_cookies = script_url;
+    resource_request->request_initiator = request_initiator;
+    resource_request->referrer = sanitized_referrer.url,
+    resource_request->referrer_policy = Referrer::ReferrerPolicyForUrlRequest(
+        outside_fetch_client_settings_object->referrer_policy);
+    resource_request->resource_type = static_cast<int>(resource_type);
+
+    // For a classic worker script request:
+    // https://html.spec.whatwg.org/C/#fetch-a-classic-worker-script
+    // Step 1: "Let request be a new request whose ..., mode is "same-origin",
+    // ..."
+    //
+    // For a module worker script request:
+    // https://html.spec.whatwg.org/C/#fetch-a-single-module-script
+    // Step 6: "If destination is "worker" or "sharedworker" and the top-level
+    // module fetch flag is set, then set request's mode to "same-origin"."
+    resource_request->mode = network::mojom::RequestMode::kSameOrigin;
+
+    // When the credentials mode is "omit", clear |allow_credentials| and set
+    // load flags to disable sending credentials according to the comments in
+    // CorsURLLoaderFactory::IsSane().
+    // TODO(https://crbug.com/799935): Unify |LOAD_DO_NOT_*| into
+    // |allow_credentials|.
+    resource_request->credentials_mode = credentials_mode;
+    if (credentials_mode == network::mojom::CredentialsMode::kOmit) {
+      resource_request->allow_credentials = false;
+      const auto load_flags_pattern = net::LOAD_DO_NOT_SAVE_COOKIES |
+                                      net::LOAD_DO_NOT_SEND_COOKIES |
+                                      net::LOAD_DO_NOT_SEND_AUTH_DATA;
+      resource_request->load_flags |= load_flags_pattern;
+    }
+
+    switch (resource_type) {
+      case ResourceType::kWorker:
+        resource_request->fetch_request_context_type =
+            static_cast<int>(blink::mojom::RequestContextType::WORKER);
+        break;
+      case ResourceType::kSharedWorker:
+        resource_request->fetch_request_context_type =
+            static_cast<int>(blink::mojom::RequestContextType::SHARED_WORKER);
+        break;
+      default:
+        NOTREACHED() << static_cast<int>(resource_type);
+        break;
+    }
+
+    AddAdditionalRequestHeaders(resource_request.get(), browser_context);
   }
 
-  AddAdditionalRequestHeaders(resource_request.get(), browser_context);
-
   // When navigation on UI is enabled, service worker and appcache work on the
   // UI thread.
   if (NavigationURLLoaderImpl::IsNavigationLoaderOnUIEnabled()) {
@@ -282,6 +285,26 @@ WorkerScriptFetchInitiator::CreateFactoryBundle(
         url::kFileScheme, file_factory_ptr.PassInterface());
   }
 
+  // Use RenderProcessHost's network factory as the default factory if
+  // NetworkService is off. If NetworkService is on the default factory is
+  // set in CreateScriptLoaderOnIO().
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService)) {
+    // Using an opaque origin here should be safe - the URLLoaderFactory created
+    // for such origin shouldn't have any special privileges.  Additionally, the
+    // origin should not be inspected at all in the legacy, non-NetworkService
+    // path.
+    const url::Origin kSafeOrigin = url::Origin();
+
+    mojo::PendingRemote<network::mojom::URLLoaderFactory>
+          pending_default_factory;
+    // TODO(crbug.com/955476): Populate the network isolation key.
+    RenderProcessHost::FromID(worker_process_id)
+        ->CreateURLLoaderFactory(
+            kSafeOrigin, nullptr /* preferences */, net::NetworkIsolationKey(),
+            nullptr /* header_client */, pending_default_factory.InitWithNewPipeAndPassReceiver());
+    factory_bundle->pending_default_factory() = std::move(pending_default_factory);
+  }
+
   return factory_bundle;
 }
 
@@ -291,6 +314,7 @@ void WorkerScriptFetchInitiator::AddAdditionalRequestHeaders(
     network::ResourceRequest* resource_request,
     BrowserContext* browser_context) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  DCHECK(base::FeatureList::IsEnabled(network::features::kNetworkService));
 
   // TODO(nhiroki): Return early when the request is neither HTTP nor HTTPS
   // (i.e., Blob URL or Data URL). This should be checked by
@@ -326,6 +350,7 @@ void WorkerScriptFetchInitiator::CreateScriptLoaderOnUI(
     scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory_override,
     CompletionCallback callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  DCHECK(base::FeatureList::IsEnabled(network::features::kNetworkService));
 
   // Create the URL loader factory for WorkerScriptLoaderFactory to use to load
   // the main script.
@@ -390,7 +415,7 @@ void WorkerScriptFetchInitiator::CreateScriptLoaderOnUI(
           std::move(url_loader_factory)),
       std::move(throttles), std::move(resource_request),
       base::BindOnce(WorkerScriptFetchInitiator::DidCreateScriptLoader,
-                     std::move(callback),
+                     std::move(callback), nullptr /* main_script_loader_factory */,
                      std::move(subresource_loader_factories)));
 }
 
@@ -415,20 +440,22 @@ void WorkerScriptFetchInitiator::CreateScriptLoaderOnIO(
   DCHECK(resource_context);
   DCHECK(service_worker_handle_core);
 
-  auto resource_type =
-      static_cast<ResourceType>(resource_request->resource_type);
-  auto provider_type = blink::mojom::ServiceWorkerProviderType::kUnknown;
-  switch (resource_type) {
-    case ResourceType::kWorker:
-      provider_type =
-          blink::mojom::ServiceWorkerProviderType::kForDedicatedWorker;
-      break;
-    case ResourceType::kSharedWorker:
-      provider_type = blink::mojom::ServiceWorkerProviderType::kForSharedWorker;
-      break;
-    default:
-      NOTREACHED() << resource_request->resource_type;
-      break;
+  if (resource_request) {
+      auto resource_type =
+          static_cast<ResourceType>(resource_request->resource_type);
+      auto provider_type = blink::mojom::ServiceWorkerProviderType::kUnknown;
+      switch (resource_type) {
+        case ResourceType::kWorker:
+          provider_type =
+              blink::mojom::ServiceWorkerProviderType::kForDedicatedWorker;
+          break;
+        case ResourceType::kSharedWorker:
+          provider_type = blink::mojom::ServiceWorkerProviderType::kForSharedWorker;
+          break;
+        default:
+          NOTREACHED() << resource_request->resource_type;
+          break;
+      }
   }
 
   // Create the URL loader factory for WorkerScriptLoaderFactory to use to load
@@ -445,18 +472,20 @@ void WorkerScriptFetchInitiator::CreateScriptLoaderOnIO(
         std::move(url_loader_factory_override_info));
   } else {
     // Add the default factory to the bundle for browser.
-    DCHECK(factory_bundle_for_browser_info);
-
-    // Get the direct network factory from |loader_factory_getter|. This doesn't
-    // support reconnection to the network service after a crash, but it's OK
-    // since it's used only for a single request to fetch the worker's main
-    // script during startup. If the network service crashes, worker startup
-    // should simply fail.
-    network::mojom::URLLoaderFactoryPtr network_factory_ptr;
-    loader_factory_getter->CloneNetworkFactory(
-        mojo::MakeRequest(&network_factory_ptr));
-    factory_bundle_for_browser_info->pending_default_factory() =
-        network_factory_ptr.PassInterface();
+    if (base::FeatureList::IsEnabled(network::features::kNetworkService)) {
+        DCHECK(factory_bundle_for_browser_info);
+
+        // Get the direct network factory from |loader_factory_getter|. This doesn't
+        // support reconnection to the network service after a crash, but it's OK
+        // since it's used only for a single request to fetch the worker's main
+        // script during startup. If the network service crashes, worker startup
+        // should simply fail.
+        network::mojom::URLLoaderFactoryPtr network_factory_ptr;
+        loader_factory_getter->CloneNetworkFactory(
+            mojo::MakeRequest(&network_factory_ptr));
+        factory_bundle_for_browser_info->pending_default_factory() =
+            network_factory_ptr.PassInterface();
+    }
     url_loader_factory = base::MakeRefCounted<blink::URLLoaderFactoryBundle>(
         std::move(factory_bundle_for_browser_info));
   }
@@ -476,34 +505,56 @@ void WorkerScriptFetchInitiator::CreateScriptLoaderOnIO(
       &ServiceWorkerContextWrapper::resource_context, service_worker_context);
 
   // Start loading a web worker main script.
-  // TODO(nhiroki): Figure out what we should do in |wc_getter| for loading web
-  // worker's main script. Returning the WebContents of the closest ancestor's
-  // frame is a possible option, but it doesn't work when a shared worker
-  // creates a dedicated worker after the closest ancestor's frame is gone. The
-  // frame tree node ID has the same issue.
-  base::RepeatingCallback<WebContents*()> wc_getter =
-      base::BindRepeating([]() -> WebContents* { return nullptr; });
-  std::vector<std::unique_ptr<URLLoaderThrottle>> throttles =
-      GetContentClient()->browser()->CreateURLLoaderThrottlesOnIO(
-          *resource_request, resource_context, wc_getter,
-          nullptr /* navigation_ui_data */,
-          RenderFrameHost::kNoFrameTreeNodeId);
+  if (base::FeatureList::IsEnabled(network::features::kNetworkService)) {
+      // TODO(nhiroki): Figure out what we should do in |wc_getter| for loading web
+      // worker's main script. Returning the WebContents of the closest ancestor's
+      // frame is a possible option, but it doesn't work when a shared worker
+      // creates a dedicated worker after the closest ancestor's frame is gone. The
+      // frame tree node ID has the same issue.
+      base::RepeatingCallback<WebContents*()> wc_getter =
+          base::BindRepeating([]() -> WebContents* { return nullptr; });
+      std::vector<std::unique_ptr<URLLoaderThrottle>> throttles =
+          GetContentClient()->browser()->CreateURLLoaderThrottlesOnIO(
+              *resource_request, resource_context, wc_getter,
+              nullptr /* navigation_ui_data */,
+              RenderFrameHost::kNoFrameTreeNodeId);
+
+      WorkerScriptFetcher::CreateAndStart(
+          std::make_unique<WorkerScriptLoaderFactory>(
+              worker_process_id,
+              /*service_worker_handle=*/nullptr, service_worker_handle_core,
+              std::move(appcache_host),
+              base::RepeatingCallback<BrowserContext*(void)>(),
+              resource_context_getter, std::move(url_loader_factory)),
+          std::move(throttles), std::move(resource_request),
+          base::BindOnce(WorkerScriptFetchInitiator::DidCreateScriptLoader,
+                         std::move(callback), nullptr,
+                         std::move(subresource_loader_factories)));
+    return;
+  }
 
-  WorkerScriptFetcher::CreateAndStart(
+  // Create the WorkerScriptLoaderFactory.
+  network::mojom::URLLoaderFactoryPtr main_script_loader_factory;
+  mojo::MakeStrongBinding(
       std::make_unique<WorkerScriptLoaderFactory>(
           worker_process_id,
           /*service_worker_handle=*/nullptr, service_worker_handle_core,
           std::move(appcache_host),
           base::RepeatingCallback<BrowserContext*(void)>(),
           resource_context_getter, std::move(url_loader_factory)),
-      std::move(throttles), std::move(resource_request),
-      base::BindOnce(WorkerScriptFetchInitiator::DidCreateScriptLoader,
-                     std::move(callback),
-                     std::move(subresource_loader_factories)));
+      mojo::MakeRequest(&main_script_loader_factory));
+
+  DidCreateScriptLoader(std::move(callback),
+                        std::move(main_script_loader_factory),
+                        std::move(subresource_loader_factories),
+                        nullptr /* main_script_load_params */,
+                        base::nullopt /* subresource_loader_params */,
+                        true /* success */);
 }
 
 void WorkerScriptFetchInitiator::DidCreateScriptLoader(
     CompletionCallback callback,
+    network::mojom::URLLoaderFactoryPtr main_script_loader_factory,
     std::unique_ptr<blink::URLLoaderFactoryBundleInfo>
         subresource_loader_factories,
     blink::mojom::WorkerMainScriptLoadParamsPtr main_script_load_params,
@@ -512,18 +563,25 @@ void WorkerScriptFetchInitiator::DidCreateScriptLoader(
   // This can be the UI thread or IO thread.
   DCHECK_CURRENTLY_ON(GetLoaderThreadID());
 
+  // NetworkService (PlzWorker):
   // If a URLLoaderFactory for AppCache is supplied, use that.
   if (subresource_loader_params &&
       subresource_loader_params->pending_appcache_loader_factory) {
+    DCHECK(base::FeatureList::IsEnabled(network::features::kNetworkService));
     subresource_loader_factories->pending_appcache_factory() =
         std::move(subresource_loader_params->pending_appcache_loader_factory);
   }
 
-  // Prepare the controller service worker info to pass to the renderer.
+  // NetworkService (PlzWorker):
+  // Prepare the controller service worker info to pass to the renderer. This is
+  // only provided if NetworkService is enabled. In the non-NetworkService case,
+  // the controller is sent in SetController IPCs during the request for the web
+  // worker script.
   blink::mojom::ControllerServiceWorkerInfoPtr controller;
   base::WeakPtr<ServiceWorkerObjectHost> controller_service_worker_object_host;
   if (subresource_loader_params &&
       subresource_loader_params->controller_service_worker_info) {
+    DCHECK(base::FeatureList::IsEnabled(network::features::kNetworkService));
     controller =
         std::move(subresource_loader_params->controller_service_worker_info);
     controller_service_worker_object_host =
@@ -533,7 +591,9 @@ void WorkerScriptFetchInitiator::DidCreateScriptLoader(
   RunOrPostTask(
       FROM_HERE, BrowserThread::UI,
       base::BindOnce(
-          std::move(callback), std::move(subresource_loader_factories),
+          std::move(callback),
+          std::move(main_script_loader_factory),
+          std::move(subresource_loader_factories),
           std::move(main_script_load_params), std::move(controller),
           std::move(controller_service_worker_object_host), success));
 }
diff --git a/chromium/content/browser/worker_host/worker_script_fetch_initiator.h b/chromium/content/browser/worker_host/worker_script_fetch_initiator.h
index 5142cb3d066..85a900a7c27 100644
--- a/chromium/content/browser/worker_host/worker_script_fetch_initiator.h
+++ b/chromium/content/browser/worker_host/worker_script_fetch_initiator.h
@@ -52,6 +52,7 @@ struct SubresourceLoaderParams;
 class WorkerScriptFetchInitiator {
  public:
   using CompletionCallback = base::OnceCallback<void(
+      network::mojom::URLLoaderFactoryPtr,
       std::unique_ptr<blink::URLLoaderFactoryBundleInfo>,
       blink::mojom::WorkerMainScriptLoadParamsPtr,
       blink::mojom::ControllerServiceWorkerInfoPtr,
@@ -135,6 +136,7 @@ class WorkerScriptFetchInitiator {
 
   static void DidCreateScriptLoader(
       CompletionCallback callback,
+      network::mojom::URLLoaderFactoryPtr main_script_loader_factory,
       std::unique_ptr<blink::URLLoaderFactoryBundleInfo>
           subresource_loader_factories,
       blink::mojom::WorkerMainScriptLoadParamsPtr main_script_load_params,
diff --git a/chromium/content/browser/worker_host/worker_script_loader_factory.cc b/chromium/content/browser/worker_host/worker_script_loader_factory.cc
index c72ef924057..49472c875f0 100644
--- a/chromium/content/browser/worker_host/worker_script_loader_factory.cc
+++ b/chromium/content/browser/worker_host/worker_script_loader_factory.cc
@@ -36,7 +36,6 @@ WorkerScriptLoaderFactory::WorkerScriptLoaderFactory(
       resource_context_getter_(resource_context_getter),
       loader_factory_(std::move(loader_factory)) {
   DCHECK_CURRENTLY_ON(WorkerScriptFetchInitiator::GetLoaderThreadID());
-  DCHECK(base::FeatureList::IsEnabled(network::features::kNetworkService));
 
   if (service_worker_handle) {
     service_worker_handle_ = service_worker_handle->AsWeakPtr();
@@ -59,6 +58,28 @@ void WorkerScriptLoaderFactory::CreateLoaderAndStart(
     network::mojom::URLLoaderClientPtr client,
     const net::MutableNetworkTrafficAnnotationTag& traffic_annotation) {
   DCHECK_CURRENTLY_ON(WorkerScriptFetchInitiator::GetLoaderThreadID());
+
+  // When NetworkService is not enabled, this function is called from the
+  // renderer process, so use ReportBadMessage() instead of DCHECK().
+  if (!base::FeatureList::IsEnabled(network::features::kNetworkService)) {
+    // Handle only the main script. Import scripts (ResourceType::kScript)
+    // should go to the network loader or controller.
+    if (resource_request.resource_type !=
+            static_cast<int>(ResourceType::kWorker) &&
+        resource_request.resource_type !=
+            static_cast<int>(ResourceType::kSharedWorker)) {
+      mojo::ReportBadMessage(
+          "WorkerScriptLoaderFactory should only get requests for worker "
+          "scripts");
+      return;
+    }
+    if (script_loader_) {
+      mojo::ReportBadMessage(
+          "WorkerScriptLoaderFactory should be used only one time");
+      return;
+    }
+  }
+
   DCHECK(resource_request.resource_type ==
              static_cast<int>(ResourceType::kWorker) ||
          resource_request.resource_type ==
diff --git a/chromium/content/renderer/worker/embedded_shared_worker_stub.cc b/chromium/content/renderer/worker/embedded_shared_worker_stub.cc
index f2c31602a45..0136d9ae959 100644
--- a/chromium/content/renderer/worker/embedded_shared_worker_stub.cc
+++ b/chromium/content/renderer/worker/embedded_shared_worker_stub.cc
@@ -53,6 +53,7 @@ EmbeddedSharedWorkerStub::EmbeddedSharedWorkerStub(
     blink::mojom::ServiceWorkerProviderInfoForClientPtr
         service_worker_provider_info,
     const base::UnguessableToken& appcache_host_id,
+    network::mojom::URLLoaderFactoryPtr main_script_loader_factory,
     blink::mojom::WorkerMainScriptLoadParamsPtr main_script_load_params,
     std::unique_ptr<blink::URLLoaderFactoryBundleInfo>
         subresource_loader_factory_bundle_info,
@@ -66,8 +67,11 @@ EmbeddedSharedWorkerStub::EmbeddedSharedWorkerStub(
       url_(info->url),
       renderer_preferences_(renderer_preferences),
       preference_watcher_request_(std::move(preference_watcher_request)) {
-  DCHECK(base::FeatureList::IsEnabled(network::features::kNetworkService));
   DCHECK(subresource_loader_factory_bundle_info);
+  // The ID of the precreated AppCacheHost can be valid only when the
+  // NetworkService is enabled.
+  DCHECK(base::FeatureList::IsEnabled(network::features::kNetworkService) ||
+         appcache_host_id.is_empty());
 
   if (main_script_load_params) {
     response_override_ =
@@ -91,6 +95,7 @@ EmbeddedSharedWorkerStub::EmbeddedSharedWorkerStub(
   }
 
   service_worker_provider_info_ = std::move(service_worker_provider_info);
+  main_script_loader_factory_ = std::move(main_script_loader_factory);
   controller_info_ = std::move(controller_info);
 
   // If the network service crashes, then self-destruct so clients don't get
@@ -168,20 +173,35 @@ void EmbeddedSharedWorkerStub::WorkerContextDestroyed() {
 std::unique_ptr<blink::WebServiceWorkerNetworkProvider>
 EmbeddedSharedWorkerStub::CreateServiceWorkerNetworkProvider() {
   if (blink::features::IsOffMainThreadSharedWorkerScriptFetchEnabled()) {
-    // Off-the-main-thread shared worker script fetch:
+    // PlzSharedWorker w/ off-the-main-thread shared worker script fetch:
     // |response_override_| will be passed to WebWorkerFetchContextImpl in
     // CreateWorkerFetchContext() and consumed during off-the-main-thread
     // shared worker script fetch.
+    DCHECK(response_override_);
     return ServiceWorkerNetworkProviderForSharedWorker::Create(
-        std::move(service_worker_provider_info_), std::move(controller_info_),
+        std::move(service_worker_provider_info_),
+        std::move(main_script_loader_factory_), std::move(controller_info_),
         subresource_loader_factory_bundle_, IsOriginSecure(url_),
         nullptr /* response_override */);
   }
 
-  // |response_override_| is passed to DocumentLoader and consumed during
-  // on-the-main-thread shared worker script fetch.
+#if DCHECK_IS_ON()
+  if (base::FeatureList::IsEnabled(network::features::kNetworkService)) {
+    // PlzSharedWorker:
+    // |response_override_| is passed to DocumentLoader and consumed during
+    // on-the-main-thread shared worker script fetch.
+    DCHECK(response_override_);
+  } else {
+    // Legacy loading path:
+    // This path will be removed once PlzSharedWorker and off-the-main-thread
+    // shared worker script fetch are enabled by default.
+    DCHECK(!response_override_);
+  }
+#endif  // DCHECK_IS_ON()
+
   return ServiceWorkerNetworkProviderForSharedWorker::Create(
-      std::move(service_worker_provider_info_), std::move(controller_info_),
+      std::move(service_worker_provider_info_),
+      std::move(main_script_loader_factory_), std::move(controller_info_),
       subresource_loader_factory_bundle_, IsOriginSecure(url_),
       std::move(response_override_));
 }
@@ -193,7 +213,10 @@ void EmbeddedSharedWorkerStub::WaitForServiceWorkerControllerInfo(
       static_cast<ServiceWorkerNetworkProviderForSharedWorker*>(
           web_network_provider)
           ->context();
-  context->PingContainerHost(std::move(callback));
+  if (context)
+    context->PingContainerHost(std::move(callback));
+  else
+    std::move(callback).Run();
 }
 
 scoped_refptr<blink::WebWorkerFetchContext>
diff --git a/chromium/content/renderer/worker/embedded_shared_worker_stub.h b/chromium/content/renderer/worker/embedded_shared_worker_stub.h
index c4d4a615dae..4b41a7c3d99 100644
--- a/chromium/content/renderer/worker/embedded_shared_worker_stub.h
+++ b/chromium/content/renderer/worker/embedded_shared_worker_stub.h
@@ -63,6 +63,7 @@ class EmbeddedSharedWorkerStub : public blink::WebSharedWorkerClient,
       blink::mojom::ServiceWorkerProviderInfoForClientPtr
           service_worker_provider_info,
       const base::UnguessableToken& appcache_host_id,
+      network::mojom::URLLoaderFactoryPtr main_script_loader_factory,
       blink::mojom::WorkerMainScriptLoadParamsPtr main_script_load_params,
       std::unique_ptr<blink::URLLoaderFactoryBundleInfo>
           subresource_loader_factory_bundle_info,
@@ -119,13 +120,18 @@ class EmbeddedSharedWorkerStub : public blink::WebSharedWorkerClient,
   blink::mojom::ServiceWorkerProviderInfoForClientPtr
       service_worker_provider_info_;
 
+  // NetworkService: The URLLoaderFactory used for loading the shared worker
+  // main script.
+  network::mojom::URLLoaderFactoryPtr main_script_loader_factory_;
+
+  // NetworkService:
   blink::mojom::ControllerServiceWorkerInfoPtr controller_info_;
 
   // The factory bundle used for loading subresources for this shared worker.
   scoped_refptr<ChildURLLoaderFactoryBundle> subresource_loader_factory_bundle_;
 
-  // The response override parameters used for taking a resource pre-requested
-  // by the browser process.
+  // NetworkService (PlzWorker): The response override parameters used for
+  // taking a resource pre-requested by the browser process.
   std::unique_ptr<NavigationResponseOverrideParameters> response_override_;
 
   // Out-of-process NetworkService:
diff --git a/chromium/content/renderer/worker/service_worker_network_provider_for_shared_worker.cc b/chromium/content/renderer/worker/service_worker_network_provider_for_shared_worker.cc
index 0984b8164f1..1f53830a86a 100644
--- a/chromium/content/renderer/worker/service_worker_network_provider_for_shared_worker.cc
+++ b/chromium/content/renderer/worker/service_worker_network_provider_for_shared_worker.cc
@@ -10,8 +10,11 @@
 #include "content/public/common/origin_util.h"
 #include "content/renderer/loader/navigation_response_override_parameters.h"
 #include "content/renderer/loader/request_extra_data.h"
+#include "content/renderer/loader/web_url_loader_impl.h"
+#include "content/renderer/render_thread_impl.h"
 #include "content/renderer/service_worker/service_worker_provider_context.h"
 #include "services/network/public/cpp/features.h"
+#include "services/network/public/cpp/weak_wrapper_shared_url_loader_factory.h"
 #include "third_party/blink/public/common/service_worker/service_worker_utils.h"
 #include "third_party/blink/public/mojom/service_worker/service_worker_object.mojom.h"
 
@@ -20,6 +23,7 @@ namespace content {
 std::unique_ptr<ServiceWorkerNetworkProviderForSharedWorker>
 ServiceWorkerNetworkProviderForSharedWorker::Create(
     blink::mojom::ServiceWorkerProviderInfoForClientPtr info,
+    network::mojom::URLLoaderFactoryPtr script_loader_factory,
     blink::mojom::ControllerServiceWorkerInfoPtr controller_info,
     scoped_refptr<network::SharedURLLoaderFactory> fallback_loader_factory,
     bool is_secure_context,
@@ -33,6 +37,9 @@ ServiceWorkerNetworkProviderForSharedWorker::Create(
         std::move(info->client_request), std::move(info->host_ptr_info),
         std::move(controller_info), std::move(fallback_loader_factory));
   }
+  if (script_loader_factory)
+    provider->script_loader_factory_ = std::move(script_loader_factory);
+
   return provider;
 }
 
@@ -68,6 +75,22 @@ ServiceWorkerNetworkProviderForSharedWorker::CreateURLLoader(
     return nullptr;
   }
 
+  // If the |script_loader_factory_| exists, use it.
+  if (script_loader_factory_) {
+    RenderThreadImpl* render_thread = RenderThreadImpl::current();
+    if (!render_thread) {
+      // RenderThreadImpl is nullptr in some tests.
+      return nullptr;
+    }
+
+    // TODO(crbug.com/796425): Temporarily wrap the raw
+    // mojom::URLLoaderFactory pointer into SharedURLLoaderFactory.
+    return std::make_unique<WebURLLoaderImpl>(
+        render_thread->resource_dispatcher(), std::move(task_runner_handle),
+        base::MakeRefCounted<network::WeakWrapperSharedURLLoaderFactory>(
+            script_loader_factory_.get()));
+  }
+
   // Otherwise go to default resource loading.
   return nullptr;
 }
diff --git a/chromium/content/renderer/worker/service_worker_network_provider_for_shared_worker.h b/chromium/content/renderer/worker/service_worker_network_provider_for_shared_worker.h
index c98f6ceb357..0bce68b3e92 100644
--- a/chromium/content/renderer/worker/service_worker_network_provider_for_shared_worker.h
+++ b/chromium/content/renderer/worker/service_worker_network_provider_for_shared_worker.h
@@ -28,6 +28,8 @@ class ServiceWorkerNetworkProviderForSharedWorker final
  public:
   // Creates a new instance.
   // - |info|: provider info from the browser
+  // - |script_loader_factory|: the factory for loading the worker's
+  //   scripts
   // - |controller_info|: info about controller service worker
   // - |fallback_loader_factory|: the factory to use when a service worker falls
   //   back to network (unlike the default factory of this renderer, it skips
@@ -36,6 +38,7 @@ class ServiceWorkerNetworkProviderForSharedWorker final
   // - |response_override|: the main script response
   static std::unique_ptr<ServiceWorkerNetworkProviderForSharedWorker> Create(
       blink::mojom::ServiceWorkerProviderInfoForClientPtr info,
+      network::mojom::URLLoaderFactoryPtr script_loader_factory,
       blink::mojom::ControllerServiceWorkerInfoPtr controller_info,
       scoped_refptr<network::SharedURLLoaderFactory> fallback_loader_factory,
       bool is_secure_context,
@@ -66,6 +69,9 @@ class ServiceWorkerNetworkProviderForSharedWorker final
   // |context_| is null if |this| is an invalid instance, in which case there is
   // no connection to the browser process.
   scoped_refptr<ServiceWorkerProviderContext> context_;
+
+  // The URL loader factory for loading the worker's scripts.
+  network::mojom::URLLoaderFactoryPtr script_loader_factory_;
 };
 
 }  // namespace content
diff --git a/chromium/content/renderer/worker/shared_worker_factory_impl.cc b/chromium/content/renderer/worker/shared_worker_factory_impl.cc
index 0fd5d46ac86..fbf3aeaaa8c 100644
--- a/chromium/content/renderer/worker/shared_worker_factory_impl.cc
+++ b/chromium/content/renderer/worker/shared_worker_factory_impl.cc
@@ -31,6 +31,7 @@ void SharedWorkerFactoryImpl::CreateSharedWorker(
     blink::mojom::ServiceWorkerProviderInfoForClientPtr
         service_worker_provider_info,
     const base::Optional<base::UnguessableToken>& appcache_host_id,
+    network::mojom::URLLoaderFactoryPtr main_script_loader_factory,
     blink::mojom::WorkerMainScriptLoadParamsPtr main_script_load_params,
     std::unique_ptr<blink::URLLoaderFactoryBundleInfo>
         subresource_loader_factories,
@@ -44,7 +45,7 @@ void SharedWorkerFactoryImpl::CreateSharedWorker(
       *renderer_preferences, std::move(preference_watcher_request),
       std::move(content_settings), std::move(service_worker_provider_info),
       appcache_host_id.value_or(base::UnguessableToken()),
-      std::move(main_script_load_params),
+      std::move(main_script_loader_factory), std::move(main_script_load_params),
       std::move(subresource_loader_factories), std::move(controller_info),
       std::move(host), std::move(request), std::move(interface_provider));
 }
diff --git a/chromium/content/renderer/worker/shared_worker_factory_impl.h b/chromium/content/renderer/worker/shared_worker_factory_impl.h
index 42036a1cf92..5a1c84b80ff 100644
--- a/chromium/content/renderer/worker/shared_worker_factory_impl.h
+++ b/chromium/content/renderer/worker/shared_worker_factory_impl.h
@@ -6,6 +6,7 @@
 #define CONTENT_RENDERER_WORKER_SHARED_WORKER_FACTORY_IMPL_H_
 
 #include "base/macros.h"
+#include "services/network/public/mojom/url_loader_factory.mojom.h"
 #include "third_party/blink/public/mojom/service_worker/service_worker_provider.mojom.h"
 #include "third_party/blink/public/mojom/worker/shared_worker_factory.mojom.h"
 
@@ -33,6 +34,7 @@ class SharedWorkerFactoryImpl : public blink::mojom::SharedWorkerFactory {
       blink::mojom::ServiceWorkerProviderInfoForClientPtr
           service_worker_provider_info,
       const base::Optional<base::UnguessableToken>& appcache_host_id,
+      network::mojom::URLLoaderFactoryPtr main_script_loader_factory,
       blink::mojom::WorkerMainScriptLoadParamsPtr main_script_load_params,
       std::unique_ptr<blink::URLLoaderFactoryBundleInfo>
           subresource_loader_factories,
diff --git a/chromium/third_party/blink/common/features.cc b/chromium/third_party/blink/common/features.cc
index 91eec38eb8e..634ec75d04c 100644
--- a/chromium/third_party/blink/common/features.cc
+++ b/chromium/third_party/blink/common/features.cc
@@ -118,12 +118,12 @@ const base::Feature kOffMainThreadDedicatedWorkerScriptFetch{
 // Enable off-the-main-thread service worker script fetch.
 // (https://crbug.com/924043)
 const base::Feature kOffMainThreadServiceWorkerScriptFetch{
-    "OffMainThreadServiceWorkerScriptFetch", base::FEATURE_ENABLED_BY_DEFAULT};
+    "OffMainThreadServiceWorkerScriptFetch", base::FEATURE_DISABLED_BY_DEFAULT};
 
 // Enable off-the-main-thread shared worker script fetch.
 // (https://crbug.com/924041)
 const base::Feature kOffMainThreadSharedWorkerScriptFetch{
-    "OffMainThreadSharedWorkerScriptFetch", base::FEATURE_ENABLED_BY_DEFAULT};
+    "OffMainThreadSharedWorkerScriptFetch", base::FEATURE_DISABLED_BY_DEFAULT};
 
 // Enable browser-initiated dedicated worker script loading
 // (PlzDedicatedWorker). https://crbug.com/906991
diff --git a/chromium/third_party/blink/public/mojom/worker/shared_worker_factory.mojom b/chromium/third_party/blink/public/mojom/worker/shared_worker_factory.mojom
index c05ed087b05..e119d0f3288 100644
--- a/chromium/third_party/blink/public/mojom/worker/shared_worker_factory.mojom
+++ b/chromium/third_party/blink/public/mojom/worker/shared_worker_factory.mojom
@@ -5,6 +5,7 @@
 module blink.mojom;
 
 import "mojo/public/mojom/base/unguessable_token.mojom";
+import "services/network/public/mojom/url_loader_factory.mojom";
 import "services/service_manager/public/mojom/interface_provider.mojom";
 import "third_party/blink/public/mojom/loader/url_loader_factory_bundle.mojom";
 import "third_party/blink/public/mojom/renderer_preference_watcher.mojom";
@@ -46,21 +47,40 @@ interface SharedWorkerFactory {
       // not http(s) or another service worker supported scheme.
       ServiceWorkerProviderInfoForClient? service_worker_provider_info,
 
+      // NetworkService:
       // The ID of the AppCacheHost in the browser process that serves resources
       // for this shared worker. This is not specified when AppCache doesn't
       // serve resources for this shared worker.
       mojo_base.mojom.UnguessableToken? appcache_host_id,
 
+      // Non-NetworkService:
+      // The URLLoaderFactory to use to request the shared worker's script
+      // (just the main script resource; importScripts() should go through the
+      // usual loader or the controller service worker if appropriate).
+      //
+      // This is only non-null when NetworkService is disabled.
+      network.mojom.URLLoaderFactory? main_script_loader_factory,
+
+      // NetworkService (PlzWorker):
       // Used for passing the main script pre-requested by the browser process
       // and its redirect information.
-      WorkerMainScriptLoadParams main_script_load_params,
+      WorkerMainScriptLoadParams? main_script_load_params,
 
-      // Used for loading subresources. This also supports non-network URLs like
-      // chrome-extension:// URLs.
-      URLLoaderFactoryBundle subresource_loader_factories,
+      // NetworkService:
+      // When the Network Service is enabled, |subresource_loader_factories|
+      // may also be provided a means for the shared worker to load
+      // subresources where applicable. For example, this allows the shared
+      // worker to load chrome-extension:// URLs which the renderer's default
+      // loader factory can't load.
+      URLLoaderFactoryBundle? subresource_loader_factories,
 
+      // NetworkService (PlzWorker):
       // Used to make fetches from the worker go through the controller service
-      // worker. This is null when there're no controller service worker.
+      // worker. This is null when
+      // NetworkService is disabled or there is no controller service worker.
+      //
+      // In non-NetworkService, the controller is sent via
+      // ServiceWorkerContainer.SetController().
       ControllerServiceWorkerInfo? controller_info,
 
       SharedWorkerHost host,