ES Modules: Specify "destination" for module loading

This CL passes the "destination"[1] parameter through module loaders. This enables
workers/worklets to specify a unique destination defined in each spec.

Before this CL, any module scripts are loaded with the "script" destination.
After this CL, top-level and descendant module scripts for dedicated workers are
loaded with the "worker" destination, top-level and descendant module scripts
for documents and dynamic import() are still loaded with the "script"
destination though. Module scripts for worklets also must be loaded with their
own destination defined in each worklet spec (e.g., "paintworklet"), but such
destinations haven't been added yet and the "script" destination is still used.
Shared workers and service workers haven't supported module loading yet.
Subsequent CLs will address them.

Regarding detailed changes, this CL adds the "destination" parameters to
components for module loading, stops ScriptResource overriding the
"destination", and uses the given "destination" instead. Note that, in Chrome,
WebURLRequest::RequestContext enum[2] represents the "destination".

[1] https://fetch.spec.whatwg.org/#concept-request-destination
[2] https://chromium.googlesource.com/chromium/src/+/a204023d46bc02634f1c6f164cae99d327d53b86/third_party/blink/public/platform/web_url_request.h#73

Bug: 842566
Change-Id: Ib777fcc28de62e1c348ef5c79f97079e5399abaf
Reviewed-on: https://chromium-review.googlesource.com/1058734
Commit-Queue: Hiroki Nakagawa <nhiroki@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Cr-Commit-Position: refs/heads/master@{#559493}

third_party/blink/renderer/core/loader/document_loader.cc

@@ -32,6 +32,7 @@
 #include <memory>
 #include "third_party/blink/public/platform/modules/serviceworker/web_service_worker_network_provider.h"
 #include "third_party/blink/public/platform/platform.h"
+#include "third_party/blink/public/platform/web_url_request.h"
 #include "third_party/blink/public/web/web_history_commit_type.h"
 #include "third_party/blink/renderer/core/dom/document.h"
 #include "third_party/blink/renderer/core/dom/document_parser.h"
@@ -211,6 +212,7 @@ Resource* DocumentLoader::StartPreload(Resource::Type type,
       resource = ImageResource::Fetch(params, Fetcher());
       break;
     case Resource::kScript:
+      params.SetRequestContext(WebURLRequest::kRequestContextScript);
       resource = ScriptResource::Fetch(params, Fetcher(), nullptr);
       break;
     case Resource::kCSSStyleSheet:

third_party/blink/renderer/core/loader/link_loader.cc

@@ -463,6 +463,8 @@ static void ModulePreloadIfNeeded(const LinkLoadParameters& params,
       link_loader->DispatchLinkLoadingErroredAsync();
     return;
   }
+  WebURLRequest::RequestContext destination =
+      WebURLRequest::kRequestContextScript;
 
   // Step 4. "Parse the URL given by the href attribute, relative to the
   // element's node document. If that fails, then return. Otherwise, let url be
@@ -523,7 +525,7 @@ static void ModulePreloadIfNeeded(const LinkLoadParameters& params,
   // metadata is "not-parser-inserted", and credentials mode is credentials
   // mode." [spec text]
   ModuleScriptFetchRequest request(
-      params.href,
+      params.href, destination,
       ScriptFetchOptions(params.nonce, integrity_metadata, params.integrity,
                          kNotParserInserted, credentials_mode),
       Referrer::NoReferrer(), params.referrer_policy,

third_party/blink/renderer/core/loader/modulescript/module_script_fetch_request.h

@@ -5,6 +5,7 @@
 #ifndef THIRD_PARTY_BLINK_RENDERER_CORE_LOADER_MODULESCRIPT_MODULE_SCRIPT_FETCH_REQUEST_H_
 #define THIRD_PARTY_BLINK_RENDERER_CORE_LOADER_MODULESCRIPT_MODULE_SCRIPT_FETCH_REQUEST_H_
 
+#include "third_party/blink/public/platform/web_url_request.h"
 #include "third_party/blink/renderer/platform/loader/fetch/script_fetch_options.h"
 #include "third_party/blink/renderer/platform/weborigin/kurl.h"
 #include "third_party/blink/renderer/platform/weborigin/referrer.h"
@@ -21,11 +22,13 @@ class ModuleScriptFetchRequest final {
   // Referrer is set only for internal module script fetch algorithms triggered
   // from ModuleTreeLinker to fetch descendant module scripts.
   ModuleScriptFetchRequest(const KURL& url,
+                           WebURLRequest::RequestContext destination,
                            const ScriptFetchOptions& options,
                            const String& referrer,
                            ReferrerPolicy referrer_policy,
                            const TextPosition& referrer_position)
       : url_(url),
+        destination_(destination),
         options_(options),
         referrer_(referrer),
         referrer_policy_(referrer_policy),
@@ -33,12 +36,14 @@ class ModuleScriptFetchRequest final {
 
   static ModuleScriptFetchRequest CreateForTest(const KURL& url) {
     return ModuleScriptFetchRequest(
-        url, ScriptFetchOptions(), Referrer::NoReferrer(),
-        kReferrerPolicyDefault, TextPosition::MinimumPosition());
+        url, WebURLRequest::kRequestContextScript, ScriptFetchOptions(),
+        Referrer::NoReferrer(), kReferrerPolicyDefault,
+        TextPosition::MinimumPosition());
   }
   ~ModuleScriptFetchRequest() = default;
 
   const KURL& Url() const { return url_; }
+  WebURLRequest::RequestContext Destination() const { return destination_; }
   const ScriptFetchOptions& Options() const { return options_; }
   const AtomicString& GetReferrer() const { return referrer_; }
   ReferrerPolicy GetReferrerPolicy() const { return referrer_policy_; }
@@ -46,6 +51,7 @@ class ModuleScriptFetchRequest final {
 
  private:
   const KURL url_;
+  const WebURLRequest::RequestContext destination_;
   const ScriptFetchOptions options_;
   const AtomicString referrer_;
   const ReferrerPolicy referrer_policy_;

third_party/blink/renderer/core/loader/modulescript/module_script_loader.cc

@@ -90,9 +90,10 @@ void ModuleScriptLoader::Fetch(const ModuleScriptFetchRequest& module_request,
   url_ = module_request.Url();
 #endif
 
-  ResourceLoaderOptions options;
+  // "destination is destination," [spec text]
+  resource_request.SetRequestContext(module_request.Destination());
 
-  // TODO(kouhei): handle "destination is destination,"
+  ResourceLoaderOptions options;
 
   // Step 6. "Set up the module script request given request and options."
   // [spec text]

third_party/blink/renderer/core/loader/modulescript/module_tree_linker.cc

@@ -17,32 +17,41 @@
 
 namespace blink {
 
-ModuleTreeLinker* ModuleTreeLinker::Fetch(const KURL& url,
+ModuleTreeLinker* ModuleTreeLinker::Fetch(
+    const KURL& url,
     const KURL& base_url,
+    WebURLRequest::RequestContext destination,
     const ScriptFetchOptions& options,
     Modulator* modulator,
     ModuleTreeLinkerRegistry* registry,
     ModuleTreeClient* client) {
-  ModuleTreeLinker* fetcher = new ModuleTreeLinker(modulator, registry, client);
+  ModuleTreeLinker* fetcher =
+      new ModuleTreeLinker(destination, modulator, registry, client);
   fetcher->FetchRoot(url, base_url, options);
   return fetcher;
 }
 
 ModuleTreeLinker* ModuleTreeLinker::FetchDescendantsForInlineScript(
     ModuleScript* module_script,
+    WebURLRequest::RequestContext destination,
     Modulator* modulator,
     ModuleTreeLinkerRegistry* registry,
     ModuleTreeClient* client) {
   DCHECK(module_script);
-  ModuleTreeLinker* fetcher = new ModuleTreeLinker(modulator, registry, client);
+  ModuleTreeLinker* fetcher =
+      new ModuleTreeLinker(destination, modulator, registry, client);
   fetcher->FetchRootInline(module_script);
   return fetcher;
 }
 
-ModuleTreeLinker::ModuleTreeLinker(Modulator* modulator,
+ModuleTreeLinker::ModuleTreeLinker(WebURLRequest::RequestContext destination,
+                                   Modulator* modulator,
                                    ModuleTreeLinkerRegistry* registry,
                                    ModuleTreeClient* client)
-    : modulator_(modulator), registry_(registry), client_(client) {
+    : destination_(destination),
+      modulator_(modulator),
+      registry_(registry),
+      client_(client) {
   CHECK(modulator);
   CHECK(registry);
   CHECK(client);
@@ -170,9 +179,9 @@ void ModuleTreeLinker::FetchRoot(const KURL& original_url,
 
   // Step 2. Perform the internal module script graph fetching procedure given
   // ... with the top-level module fetch flag set. ...
-  ModuleScriptFetchRequest request(url, options, Referrer::NoReferrer(),
-                                   modulator_->GetReferrerPolicy(),
-                                   TextPosition::MinimumPosition());
+  ModuleScriptFetchRequest request(
+      url, destination_, options, Referrer::NoReferrer(),
+      modulator_->GetReferrerPolicy(), TextPosition::MinimumPosition());
 
   InitiateInternalModuleScriptGraphFetching(
       request, ModuleGraphLevel::kTopLevelModuleFetch);
@@ -361,7 +370,7 @@ void ModuleTreeLinker::FetchDescendants(ModuleScript* module_script) {
     // [FD] Step 7. ... perform the internal module script graph fetching
     // procedure given ... with the top-level module fetch flag unset. ...
     ModuleScriptFetchRequest request(
-        urls[i], options, module_script->BaseURL().GetString(),
+        urls[i], destination_, options, module_script->BaseURL().GetString(),
         modulator_->GetReferrerPolicy(), positions[i]);
     InitiateInternalModuleScriptGraphFetching(
         request, ModuleGraphLevel::kDependentModuleFetch);

third_party/blink/renderer/core/loader/modulescript/module_tree_linker.h

@@ -5,6 +5,7 @@
 #ifndef THIRD_PARTY_BLINK_RENDERER_CORE_LOADER_MODULESCRIPT_MODULE_TREE_LINKER_H_
 #define THIRD_PARTY_BLINK_RENDERER_CORE_LOADER_MODULESCRIPT_MODULE_TREE_LINKER_H_
 
+#include "third_party/blink/public/platform/web_url_request.h"
 #include "third_party/blink/renderer/core/core_export.h"
 #include "third_party/blink/renderer/core/script/modulator.h"
 #include "third_party/blink/renderer/platform/bindings/script_wrappable.h"
@@ -40,6 +41,7 @@ class CORE_EXPORT ModuleTreeLinker final : public SingleModuleClient {
   // removed soon once an upcoming spec change lands.
   static ModuleTreeLinker* Fetch(const KURL&,
                                  const KURL& base_url,
+                                 WebURLRequest::RequestContext destination,
                                  const ScriptFetchOptions&,
                                  Modulator*,
                                  ModuleTreeLinkerRegistry*,
@@ -48,6 +50,7 @@ class CORE_EXPORT ModuleTreeLinker final : public SingleModuleClient {
   // [FDaI] for an inline script.
   static ModuleTreeLinker* FetchDescendantsForInlineScript(
       ModuleScript*,
+      WebURLRequest::RequestContext destination,
       Modulator*,
       ModuleTreeLinkerRegistry*,
       ModuleTreeClient*);
@@ -62,7 +65,10 @@ class CORE_EXPORT ModuleTreeLinker final : public SingleModuleClient {
   bool HasFinished() const { return state_ == State::kFinished; }
 
  private:
-  ModuleTreeLinker(Modulator*, ModuleTreeLinkerRegistry*, ModuleTreeClient*);
+  ModuleTreeLinker(WebURLRequest::RequestContext destination,
+                   Modulator*,
+                   ModuleTreeLinkerRegistry*,
+                   ModuleTreeClient*);
 
   enum class State {
     kInitial,
@@ -102,6 +108,7 @@ class CORE_EXPORT ModuleTreeLinker final : public SingleModuleClient {
   ScriptValue FindFirstParseError(ModuleScript*,
                                   HeapHashSet<Member<ModuleScript>>*) const;
 
+  const WebURLRequest::RequestContext destination_;
   const Member<Modulator> modulator_;
   HashSet<KURL> visited_set_;
   const Member<ModuleTreeLinkerRegistry> registry_;

third_party/blink/renderer/core/loader/modulescript/module_tree_linker_registry.cc

@@ -23,11 +23,12 @@ void ModuleTreeLinkerRegistry::TraceWrappers(
 ModuleTreeLinker* ModuleTreeLinkerRegistry::Fetch(
     const KURL& url,
     const KURL& base_url,
+    WebURLRequest::RequestContext destination,
     const ScriptFetchOptions& options,
     Modulator* modulator,
     ModuleTreeClient* client) {
-  ModuleTreeLinker* fetcher =
-      ModuleTreeLinker::Fetch(url, base_url, options, modulator, this, client);
+  ModuleTreeLinker* fetcher = ModuleTreeLinker::Fetch(
+      url, base_url, destination, options, modulator, this, client);
   DCHECK(fetcher->IsFetching());
   active_tree_linkers_.insert(fetcher);
   return fetcher;
@@ -35,10 +36,11 @@ ModuleTreeLinker* ModuleTreeLinkerRegistry::Fetch(
 
 ModuleTreeLinker* ModuleTreeLinkerRegistry::FetchDescendantsForInlineScript(
     ModuleScript* module_script,
+    WebURLRequest::RequestContext destination,
     Modulator* modulator,
     ModuleTreeClient* client) {
   ModuleTreeLinker* fetcher = ModuleTreeLinker::FetchDescendantsForInlineScript(
-      module_script, modulator, this, client);
+      module_script, destination, modulator, this, client);
   DCHECK(fetcher->IsFetching());
   active_tree_linkers_.insert(fetcher);
   return fetcher;

third_party/blink/renderer/core/loader/modulescript/module_tree_linker_registry.h

@@ -5,6 +5,7 @@
 #ifndef THIRD_PARTY_BLINK_RENDERER_CORE_LOADER_MODULESCRIPT_MODULE_TREE_LINKER_REGISTRY_H_
 #define THIRD_PARTY_BLINK_RENDERER_CORE_LOADER_MODULESCRIPT_MODULE_TREE_LINKER_REGISTRY_H_
 
+#include "third_party/blink/public/platform/web_url_request.h"
 #include "third_party/blink/renderer/core/core_export.h"
 #include "third_party/blink/renderer/platform/bindings/script_wrappable.h"
 #include "third_party/blink/renderer/platform/bindings/trace_wrapper_member.h"
@@ -35,10 +36,13 @@ class CORE_EXPORT ModuleTreeLinkerRegistry
 
   ModuleTreeLinker* Fetch(const KURL&,
                           const KURL& base_url,
+                          WebURLRequest::RequestContext destination,
                           const ScriptFetchOptions&,
                           Modulator*,
                           ModuleTreeClient*);
-  ModuleTreeLinker* FetchDescendantsForInlineScript(ModuleScript*,
+  ModuleTreeLinker* FetchDescendantsForInlineScript(
+      ModuleScript*,
+      WebURLRequest::RequestContext destination,
       Modulator*,
       ModuleTreeClient*);
 

third_party/blink/renderer/core/loader/modulescript/module_tree_linker_test.cc

@@ -7,6 +7,7 @@
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/blink/public/platform/platform.h"
 #include "third_party/blink/public/platform/scheduler/web_main_thread_scheduler.h"
+#include "third_party/blink/public/platform/web_url_request.h"
 #include "third_party/blink/renderer/bindings/core/v8/script_module.h"
 #include "third_party/blink/renderer/bindings/core/v8/v8_binding_for_core.h"
 #include "third_party/blink/renderer/bindings/core/v8/v8_binding_for_testing.h"
@@ -199,7 +200,8 @@ TEST_F(ModuleTreeLinkerTest, FetchTreeNoDeps) {
 
   KURL url("http://example.com/root.js");
   TestModuleTreeClient* client = new TestModuleTreeClient;
-  registry->Fetch(url, NullURL(), ScriptFetchOptions(), GetModulator(), client);
+  registry->Fetch(url, NullURL(), WebURLRequest::kRequestContextScript,
+                  ScriptFetchOptions(), GetModulator(), client);
 
   EXPECT_FALSE(client->WasNotifyFinished())
       << "ModuleTreeLinker should always finish asynchronously.";
@@ -218,7 +220,8 @@ TEST_F(ModuleTreeLinkerTest, FetchTreeInstantiationFailure) {
 
   KURL url("http://example.com/root.js");
   TestModuleTreeClient* client = new TestModuleTreeClient;
-  registry->Fetch(url, NullURL(), ScriptFetchOptions(), GetModulator(), client);
+  registry->Fetch(url, NullURL(), WebURLRequest::kRequestContextScript,
+                  ScriptFetchOptions(), GetModulator(), client);
 
   EXPECT_FALSE(client->WasNotifyFinished())
       << "ModuleTreeLinker should always finish asynchronously.";
@@ -241,7 +244,8 @@ TEST_F(ModuleTreeLinkerTest, FetchTreeWithSingleDependency) {
 
   KURL url("http://example.com/root.js");
   TestModuleTreeClient* client = new TestModuleTreeClient;
-  registry->Fetch(url, NullURL(), ScriptFetchOptions(), GetModulator(), client);
+  registry->Fetch(url, NullURL(), WebURLRequest::kRequestContextScript,
+                  ScriptFetchOptions(), GetModulator(), client);
 
   EXPECT_FALSE(client->WasNotifyFinished())
       << "ModuleTreeLinker should always finish asynchronously.";
@@ -265,7 +269,8 @@ TEST_F(ModuleTreeLinkerTest, FetchTreeWith3Deps) {
 
   KURL url("http://example.com/root.js");
   TestModuleTreeClient* client = new TestModuleTreeClient;
-  registry->Fetch(url, NullURL(), ScriptFetchOptions(), GetModulator(), client);
+  registry->Fetch(url, NullURL(), WebURLRequest::kRequestContextScript,
+                  ScriptFetchOptions(), GetModulator(), client);
 
   EXPECT_FALSE(client->WasNotifyFinished())
       << "ModuleTreeLinker should always finish asynchronously.";
@@ -302,7 +307,8 @@ TEST_F(ModuleTreeLinkerTest, FetchTreeWith3Deps1Fail) {
 
   KURL url("http://example.com/root.js");
   TestModuleTreeClient* client = new TestModuleTreeClient;
-  registry->Fetch(url, NullURL(), ScriptFetchOptions(), GetModulator(), client);
+  registry->Fetch(url, NullURL(), WebURLRequest::kRequestContextScript,
+                  ScriptFetchOptions(), GetModulator(), client);
 
   EXPECT_FALSE(client->WasNotifyFinished())
       << "ModuleTreeLinker should always finish asynchronously.";
@@ -358,7 +364,8 @@ TEST_F(ModuleTreeLinkerTest, FetchDependencyTree) {
 
   KURL url("http://example.com/depth1.js");
   TestModuleTreeClient* client = new TestModuleTreeClient;
-  registry->Fetch(url, NullURL(), ScriptFetchOptions(), GetModulator(), client);
+  registry->Fetch(url, NullURL(), WebURLRequest::kRequestContextScript,
+                  ScriptFetchOptions(), GetModulator(), client);
 
   EXPECT_FALSE(client->WasNotifyFinished())
       << "ModuleTreeLinker should always finish asynchronously.";
@@ -381,7 +388,8 @@ TEST_F(ModuleTreeLinkerTest, FetchDependencyOfCyclicGraph) {
 
   KURL url("http://example.com/a.js");
   TestModuleTreeClient* client = new TestModuleTreeClient;
-  registry->Fetch(url, NullURL(), ScriptFetchOptions(), GetModulator(), client);
+  registry->Fetch(url, NullURL(), WebURLRequest::kRequestContextScript,
+                  ScriptFetchOptions(), GetModulator(), client);
 
   EXPECT_FALSE(client->WasNotifyFinished())
       << "ModuleTreeLinker should always finish asynchronously.";

third_party/blink/renderer/core/loader/resource/script_resource.cc

@@ -43,6 +43,30 @@
 
 namespace blink {
 
+namespace {
+
+// Returns true if the given request context is a script-like destination
+// defined in the Fetch spec:
+// https://fetch.spec.whatwg.org/#request-destination-script-like
+bool IsRequestContextSupported(WebURLRequest::RequestContext request_context) {
+  // TODO(nhiroki): Support |kRequestContextSharedWorker| for module loading for
+  // shared workers (https://crbug.com/824646).
+  // TODO(nhiroki): Support |kRequestContextServiceWorker| for module loading
+  // for service workers (https://crbug.com/824647).
+  // TODO(nhiroki): Support "audioworklet" and "paintworklet" destinations.
+  switch (request_context) {
+    case WebURLRequest::kRequestContextScript:
+    case WebURLRequest::kRequestContextWorker:
+      return true;
+    default:
+      break;
+  }
+  NOTREACHED() << "Incompatible request context type: " << request_context;
+  return false;
+}
+
+}  // namespace
+
 // SingleCachedMetadataHandlerImpl should be created when a response is
 // received, and can be used independently from Resource. - It doesn't have any
 // references to Resource. Necessary data are captured
@@ -151,7 +175,8 @@ ScriptResource* ScriptResource::Fetch(FetchParameters& params,
                                       ResourceClient* client) {
   DCHECK_EQ(params.GetResourceRequest().GetFrameType(),
             network::mojom::RequestContextFrameType::kNone);
-  params.SetRequestContext(WebURLRequest::kRequestContextScript);
+  DCHECK(IsRequestContextSupported(
+      params.GetResourceRequest().GetRequestContext()));
   return ToScriptResource(
       fetcher->RequestResource(params, ScriptResourceFactory(), client));
 }

third_party/blink/renderer/core/script/dynamic_module_resolver.cc

@@ -4,6 +4,7 @@
 
 #include "third_party/blink/renderer/core/script/dynamic_module_resolver.h"
 
+#include "third_party/blink/public/platform/web_url_request.h"
 #include "third_party/blink/renderer/bindings/core/v8/exception_state.h"
 #include "third_party/blink/renderer/bindings/core/v8/referrer_script_info.h"
 #include "third_party/blink/renderer/bindings/core/v8/script_promise_resolver.h"
@@ -212,7 +213,8 @@ void DynamicModuleResolver::ResolveDynamically(
   // with result."
   auto* tree_client =
       DynamicImportTreeClient::Create(url, modulator_.Get(), promise_resolver);
-  modulator_->FetchTree(url, options, tree_client);
+  modulator_->FetchTree(url, WebURLRequest::kRequestContextScript, options,
+                        tree_client);
 
   // Steps 2.[5-8] are implemented at
   // DynamicImportTreeClient::NotifyModuleLoadFinished.

third_party/blink/renderer/core/script/dynamic_module_resolver_test.cc

@@ -62,6 +62,7 @@ class DynamicModuleResolverTestModulator final : public DummyModulator {
   }
 
   void FetchTree(const KURL& url,
+                 WebURLRequest::RequestContext,
                  const ScriptFetchOptions&,
                  ModuleTreeClient* client) final {
     EXPECT_EQ(expected_fetch_tree_url_, url);

third_party/blink/renderer/core/script/modulator.h

@@ -6,6 +6,7 @@
 #define THIRD_PARTY_BLINK_RENDERER_CORE_SCRIPT_MODULATOR_H_
 
 #include "base/single_thread_task_runner.h"
+#include "third_party/blink/public/platform/web_url_request.h"
 #include "third_party/blink/renderer/bindings/core/v8/script_module.h"
 #include "third_party/blink/renderer/core/core_export.h"
 #include "third_party/blink/renderer/core/script/module_import_meta.h"
@@ -102,6 +103,7 @@ class CORE_EXPORT Modulator : public GarbageCollectedFinalized<Modulator>,
 
   // https://html.spec.whatwg.org/multipage/webappapis.html#fetch-a-module-script-tree
   virtual void FetchTree(const KURL&,
+                         WebURLRequest::RequestContext destination,
                          const ScriptFetchOptions&,
                          ModuleTreeClient*) = 0;
 
@@ -112,7 +114,9 @@ class CORE_EXPORT Modulator : public GarbageCollectedFinalized<Modulator>,
                            ModuleGraphLevel,
                            SingleModuleClient*) = 0;
 
-  virtual void FetchDescendantsForInlineScript(ModuleScript*,
+  virtual void FetchDescendantsForInlineScript(
+      ModuleScript*,
+      WebURLRequest::RequestContext destination,
       ModuleTreeClient*) = 0;
 
   // Synchronously retrieves a single module script from existing module map

third_party/blink/renderer/core/script/modulator_impl_base.cc

@@ -52,6 +52,7 @@ const SecurityOrigin* ModulatorImplBase::GetSecurityOriginForFetch() {
 // [fetch-a-module-worker-script-tree]
 // https://html.spec.whatwg.org/multipage/webappapis.html#fetch-a-module-worker-script-tree
 void ModulatorImplBase::FetchTree(const KURL& url,
+                                  WebURLRequest::RequestContext destination,
                                   const ScriptFetchOptions& options,
                                   ModuleTreeClient* client) {
   // <spec label="fetch-a-module-script-tree" step="2">Perform the internal
@@ -67,8 +68,8 @@ void ModulatorImplBase::FetchTree(const KURL& url,
   // of this algorithm specified custom perform the fetch steps, pass those
   // along as well.</spec>
 
-  tree_linker_registry_->Fetch(url, GetExecutionContext()->BaseURL(), options,
-                               this, client);
+  tree_linker_registry_->Fetch(url, GetExecutionContext()->BaseURL(),
+                               destination, options, this, client);
 
   // <spec label="fetch-a-module-script-tree" step="3">When the internal module
   // script graph fetching procedure asynchronously completes with result,
@@ -83,9 +84,10 @@ void ModulatorImplBase::FetchTree(const KURL& url,
 
 void ModulatorImplBase::FetchDescendantsForInlineScript(
     ModuleScript* module_script,
+    WebURLRequest::RequestContext destination,
     ModuleTreeClient* client) {
-  tree_linker_registry_->FetchDescendantsForInlineScript(module_script, this,
-                                                         client);
+  tree_linker_registry_->FetchDescendantsForInlineScript(
+      module_script, destination, this, client);
 }
 
 void ModulatorImplBase::FetchSingle(const ModuleScriptFetchRequest& request,

third_party/blink/renderer/core/script/modulator_impl_base.h

@@ -52,9 +52,12 @@ class ModulatorImplBase : public Modulator {
   const SecurityOrigin* GetSecurityOriginForFetch() override;
 
   void FetchTree(const KURL&,
+                 WebURLRequest::RequestContext destination,
                  const ScriptFetchOptions&,
                  ModuleTreeClient*) override;
-  void FetchDescendantsForInlineScript(ModuleScript*,
+  void FetchDescendantsForInlineScript(
+      ModuleScript*,
+      WebURLRequest::RequestContext destination,
       ModuleTreeClient*) override;
   void FetchSingle(const ModuleScriptFetchRequest&,
                    ModuleGraphLevel,

third_party/blink/renderer/core/script/script_loader.cc

@@ -545,7 +545,8 @@ bool ScriptLoader::PrepareScript(const TextPosition& script_start_position,
         // completes, set the script's script to the result. At that time, the
         // script is ready.</spec>
         auto* module_tree_client = ModulePendingScriptTreeClient::Create();
-        modulator->FetchDescendantsForInlineScript(module_script,
+        modulator->FetchDescendantsForInlineScript(
+            module_script, WebURLRequest::kRequestContextScript,
             module_tree_client);
         prepared_pending_script_ = ModulePendingScript::Create(
             element_, module_tree_client, is_external_script_);
@@ -732,7 +733,8 @@ void ScriptLoader::FetchModuleScriptTree(const KURL& url,
   // Fetch a module script graph given url, settings object, "script", and
   // options.</spec>
   auto* module_tree_client = ModulePendingScriptTreeClient::Create();
-  modulator->FetchTree(url, options, module_tree_client);
+  modulator->FetchTree(url, WebURLRequest::kRequestContextScript, options,
+                       module_tree_client);
   prepared_pending_script_ = ModulePendingScript::Create(
       element_, module_tree_client, is_external_script_);
 }

third_party/blink/renderer/core/testing/dummy_modulator.cc

@@ -69,6 +69,7 @@ base::SingleThreadTaskRunner* DummyModulator::TaskRunner() {
 };
 
 void DummyModulator::FetchTree(const KURL&,
+                               WebURLRequest::RequestContext,
                                const ScriptFetchOptions&,
                                ModuleTreeClient*) {
   NOTREACHED();
@@ -80,7 +81,9 @@ void DummyModulator::FetchSingle(const ModuleScriptFetchRequest&,
   NOTREACHED();
 }
 
-void DummyModulator::FetchDescendantsForInlineScript(ModuleScript*,
+void DummyModulator::FetchDescendantsForInlineScript(
+    ModuleScript*,
+    WebURLRequest::RequestContext,
     ModuleTreeClient*) {
   NOTREACHED();
 }

third_party/blink/renderer/core/testing/dummy_modulator.h

@@ -38,12 +38,15 @@ class DummyModulator : public Modulator {
   ScriptState* GetScriptState() override;
 
   void FetchTree(const KURL&,
+                 WebURLRequest::RequestContext destination,
                  const ScriptFetchOptions&,
                  ModuleTreeClient*) override;
   void FetchSingle(const ModuleScriptFetchRequest&,
                    ModuleGraphLevel,
                    SingleModuleClient*) override;
-  void FetchDescendantsForInlineScript(ModuleScript*,
+  void FetchDescendantsForInlineScript(
+      ModuleScript*,
+      WebURLRequest::RequestContext destination,
       ModuleTreeClient*) override;
   ModuleScript* GetFetchedModuleScript(const KURL&) override;
   void FetchNewSingleModule(const ModuleScriptFetchRequest&,

third_party/blink/renderer/core/workers/dedicated_worker_global_scope.cc

@@ -33,14 +33,17 @@
 #include <memory>
 #include "third_party/blink/renderer/bindings/core/v8/exception_state.h"
 #include "third_party/blink/renderer/bindings/core/v8/serialization/serialized_script_value.h"
+#include "third_party/blink/renderer/bindings/core/v8/worker_or_worklet_script_controller.h"
 #include "third_party/blink/renderer/core/execution_context/execution_context.h"
 #include "third_party/blink/renderer/core/frame/csp/content_security_policy.h"
 #include "third_party/blink/renderer/core/inspector/thread_debugger.h"
 #include "third_party/blink/renderer/core/origin_trials/origin_trial_context.h"
+#include "third_party/blink/renderer/core/script/modulator.h"
 #include "third_party/blink/renderer/core/workers/dedicated_worker_object_proxy.h"
 #include "third_party/blink/renderer/core/workers/dedicated_worker_thread.h"
 #include "third_party/blink/renderer/core/workers/global_scope_creation_params.h"
 #include "third_party/blink/renderer/core/workers/worker_clients.h"
+#include "third_party/blink/renderer/core/workers/worker_module_tree_client.h"
 #include "third_party/blink/renderer/platform/bindings/script_state.h"
 
 namespace blink {
@@ -57,6 +60,22 @@ const AtomicString& DedicatedWorkerGlobalScope::InterfaceName() const {
   return EventTargetNames::DedicatedWorkerGlobalScope;
 }
 
+// https://html.spec.whatwg.org/multipage/workers.html#worker-processing-model
+void DedicatedWorkerGlobalScope::ImportModuleScript(
+    const KURL& module_url_record,
+    network::mojom::FetchCredentialsMode credentials_mode) {
+  // Step 12: "Let destination be "sharedworker" if is shared is true, and
+  // "worker" otherwise."
+  WebURLRequest::RequestContext destination =
+      WebURLRequest::kRequestContextWorker;
+  Modulator* modulator = Modulator::From(ScriptController()->GetScriptState());
+  // Step 13: "... Fetch a module worker script graph given url, outside
+  // settings, destination, the value of the credentials member of options, and
+  // inside settings."
+  FetchModuleScript(module_url_record, destination, credentials_mode,
+                    new WorkerModuleTreeClient(modulator));
+}
+
 void DedicatedWorkerGlobalScope::postMessage(
     ScriptState* script_state,
     scoped_refptr<SerializedScriptValue> message,

third_party/blink/renderer/core/workers/dedicated_worker_global_scope.h

@@ -58,6 +58,10 @@ class CORE_EXPORT DedicatedWorkerGlobalScope final : public WorkerGlobalScope {
   // EventTarget
   const AtomicString& InterfaceName() const override;
 
+  // WorkerGlobalScope
+  void ImportModuleScript(const KURL& module_url_record,
+                          network::mojom::FetchCredentialsMode) override;
+
   void postMessage(ScriptState*,
                    scoped_refptr<SerializedScriptValue>,
                    const MessagePortArray&,

third_party/blink/renderer/core/workers/shared_worker_global_scope.cc

@@ -62,6 +62,22 @@ const AtomicString& SharedWorkerGlobalScope::InterfaceName() const {
   return EventTargetNames::SharedWorkerGlobalScope;
 }
 
+// https://html.spec.whatwg.org/multipage/workers.html#worker-processing-model
+void SharedWorkerGlobalScope::ImportModuleScript(
+    const KURL& module_url_record,
+    network::mojom::FetchCredentialsMode credentials_mode) {
+  // Step 12: "Let destination be "sharedworker" if is shared is true, and
+  // "worker" otherwise."
+
+  // Step 13: "... Fetch a module worker script graph given url, outside
+  // settings, destination, the value of the credentials member of options, and
+  // inside settings."
+
+  // TODO(nhiroki): Implement module loading for shared workers.
+  // (https://crbug.com/824646)
+  NOTREACHED();
+}
+
 void SharedWorkerGlobalScope::ExceptionThrown(ErrorEvent* event) {
   WorkerGlobalScope::ExceptionThrown(event);
   if (WorkerThreadDebugger* debugger =

third_party/blink/renderer/core/workers/shared_worker_global_scope.h

@@ -57,6 +57,10 @@ class SharedWorkerGlobalScope final : public WorkerGlobalScope {
   // EventTarget
   const AtomicString& InterfaceName() const override;
 
+  // WorkerGlobalScope
+  void ImportModuleScript(const KURL& module_url_record,
+                          network::mojom::FetchCredentialsMode) override;
+
   // Setters/Getters for attributes in SharedWorkerGlobalScope.idl
   DEFINE_ATTRIBUTE_EVENT_LISTENER(connect);
   String name() const { return name_; }

third_party/blink/renderer/core/workers/worker_global_scope.cc

@@ -49,12 +49,10 @@
 #include "third_party/blink/renderer/core/loader/worker_threadable_loader.h"
 #include "third_party/blink/renderer/core/origin_trials/origin_trial_context.h"
 #include "third_party/blink/renderer/core/probe/core_probes.h"
-#include "third_party/blink/renderer/core/script/modulator.h"
 #include "third_party/blink/renderer/core/workers/global_scope_creation_params.h"
 #include "third_party/blink/renderer/core/workers/installed_scripts_manager.h"
 #include "third_party/blink/renderer/core/workers/worker_classic_script_loader.h"
 #include "third_party/blink/renderer/core/workers/worker_location.h"
-#include "third_party/blink/renderer/core/workers/worker_module_tree_client.h"
 #include "third_party/blink/renderer/core/workers/worker_navigator.h"
 #include "third_party/blink/renderer/core/workers/worker_reporting_proxy.h"
 #include "third_party/blink/renderer/core/workers/worker_thread.h"
@@ -327,14 +325,6 @@ void WorkerGlobalScope::EvaluateClassicScript(
   ReportingProxy().DidEvaluateClassicScript(success);
 }
 
-void WorkerGlobalScope::ImportModuleScript(
-    const KURL& module_url_record,
-    network::mojom::FetchCredentialsMode credentials_mode) {
-  Modulator* modulator = Modulator::From(ScriptController()->GetScriptState());
-  FetchModuleScript(module_url_record, credentials_mode,
-                    new WorkerModuleTreeClient(modulator));
-}
-
 WorkerGlobalScope::WorkerGlobalScope(
     std::unique_ptr<GlobalScopeCreationParams> creation_params,
     WorkerThread* thread,

third_party/blink/renderer/core/workers/worker_global_scope.h

@@ -136,8 +136,8 @@ class CORE_EXPORT WorkerGlobalScope
       std::unique_ptr<Vector<char>> cached_meta_data);
 
   // Imports the top-level module script for |module_url_record|.
-  void ImportModuleScript(const KURL& module_url_record,
-                          network::mojom::FetchCredentialsMode);
+  virtual void ImportModuleScript(const KURL& module_url_record,
+                                  network::mojom::FetchCredentialsMode) = 0;
 
   double TimeOrigin() const { return time_origin_; }
   WorkerSettings* GetWorkerSettings() const { return worker_settings_.get(); }

third_party/blink/renderer/core/workers/worker_or_worklet_global_scope.cc

@@ -203,6 +203,7 @@ void WorkerOrWorkletGlobalScope::ApplyContentSecurityPolicyFromVector(
 
 void WorkerOrWorkletGlobalScope::FetchModuleScript(
     const KURL& module_url_record,
+    WebURLRequest::RequestContext destination,
     network::mojom::FetchCredentialsMode credentials_mode,
     ModuleTreeClient* client) {
   // Step 2: "Let options be a script fetch options whose cryptographic nonce is
@@ -218,7 +219,7 @@ void WorkerOrWorkletGlobalScope::FetchModuleScript(
 
   Modulator* modulator = Modulator::From(ScriptController()->GetScriptState());
   // Step 3. "Perform the internal module script graph fetching procedure ..."
-  modulator->FetchTree(module_url_record, options, client);
+  modulator->FetchTree(module_url_record, destination, options, client);
 }
 
 void WorkerOrWorkletGlobalScope::Trace(blink::Visitor* visitor) {

third_party/blink/renderer/core/workers/worker_or_worklet_global_scope.h

@@ -7,6 +7,7 @@
 
 #include "base/single_thread_task_runner.h"
 #include "services/network/public/mojom/fetch_api.mojom-shared.h"
+#include "third_party/blink/public/platform/web_url_request.h"
 #include "third_party/blink/renderer/bindings/core/v8/v8_cache_options.h"
 #include "third_party/blink/renderer/core/dom/events/event_target.h"
 #include "third_party/blink/renderer/core/execution_context/execution_context.h"
@@ -113,6 +114,7 @@ class CORE_EXPORT WorkerOrWorkletGlobalScope : public EventTargetWithInlineData,
   // HTML spec:
   // https://html.spec.whatwg.org/multipage/webappapis.html#fetch-a-module-worker-script-tree
   void FetchModuleScript(const KURL& module_url_record,
+                         WebURLRequest::RequestContext destination,
                          network::mojom::FetchCredentialsMode,
                          ModuleTreeClient*);
 

third_party/blink/renderer/core/workers/worker_thread_test_helper.h

@@ -72,6 +72,12 @@ class FakeWorkerGlobalScope : public WorkerGlobalScope {
     return EventTargetNames::DedicatedWorkerGlobalScope;
   }
 
+  // WorkerGlobalScope
+  void ImportModuleScript(const KURL& module_url_record,
+                          network::mojom::FetchCredentialsMode) override {
+    NOTREACHED();
+  }
+
   void ExceptionThrown(ErrorEvent*) override {}
 };
 

third_party/blink/renderer/core/workers/worklet_global_scope.cc

@@ -101,7 +101,11 @@ void WorkletGlobalScope::FetchAndInvokeScript(
   WorkletModuleTreeClient* client = new WorkletModuleTreeClient(
       modulator, std::move(outside_settings_task_runner), pending_tasks);
 
-  FetchModuleScript(module_url_record, credentials_mode, client);
+  // TODO(nhiroki): Specify an appropriate destination defined in each worklet
+  // spec (e.g., "paint worklet", "audio worklet").
+  WebURLRequest::RequestContext destination =
+      WebURLRequest::kRequestContextScript;
+  FetchModuleScript(module_url_record, destination, credentials_mode, client);
 }
 
 WorkerOrWorkletModuleFetchCoordinatorProxy*

third_party/blink/renderer/core/workers/worklet_module_responses_map_test.cc

@@ -32,6 +32,9 @@ class WorkletModuleResponsesMapTest : public testing::Test {
 
   void Fetch(const KURL& url, ClientImpl* client) {
     ResourceRequest resource_request(url);
+    // TODO(nhiroki): Specify worklet-specific request context (e.g.,
+    // "paintworklet").
+    resource_request.SetRequestContext(WebURLRequest::kRequestContextScript);
     FetchParameters fetch_params(resource_request);
     map_->Fetch(fetch_params, client);
   }

third_party/blink/renderer/modules/serviceworkers/service_worker_global_scope.cc

@@ -165,6 +165,14 @@ void ServiceWorkerGlobalScope::EvaluateClassicScript(
                                            std::move(cached_meta_data));
 }
 
+void ServiceWorkerGlobalScope::ImportModuleScript(
+    const KURL& module_url_record,
+    network::mojom::FetchCredentialsMode credentials_mode) {
+  // TODO(nhiroki): Implement module loading for service workers.
+  // (https://crbug.com/824647)
+  NOTREACHED();
+}
+
 void ServiceWorkerGlobalScope::CountWorkerScript(size_t script_size,
                                                  size_t cached_metadata_size) {
   DEFINE_THREAD_SAFE_STATIC_LOCAL(

third_party/blink/renderer/modules/serviceworkers/service_worker_global_scope.h

@@ -70,6 +70,8 @@ class MODULES_EXPORT ServiceWorkerGlobalScope final : public WorkerGlobalScope {
       const KURL& script_url,
       String source_code,
       std::unique_ptr<Vector<char>> cached_meta_data) override;
+  void ImportModuleScript(const KURL& module_url_record,
+                          network::mojom::FetchCredentialsMode) override;
 
   // Counts an evaluated script and its size. Called for the main worker script.
   void CountWorkerScript(size_t script_size, size_t cached_metadata_size);

third_party/blink/renderer/platform/loader/fetch/script_fetch_options.cc

@@ -23,6 +23,7 @@ FetchParameters ScriptFetchOptions::CreateFetchParameters(
   ResourceLoaderOptions resource_loader_options;
   resource_loader_options.initiator_info.name = "script";
   FetchParameters params(resource_request, resource_loader_options);
+  params.SetRequestContext(WebURLRequest::kRequestContextScript);
 
   // Step 1. ... and CORS setting. [spec text]
   //