Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1840 insertions, 0 deletions

diff --git a/dom/workers/ScriptLoader.cpp b/dom/workers/ScriptLoader.cpp
new file mode 100644
index 0000000000..315be95ffe
--- /dev/null
+++ b/dom/workers/ScriptLoader.cpp
@@ -0,0 +1,1840 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ScriptLoader.h"
+
+#include <algorithm>
+#include <type_traits>
+
+#include "nsIChannel.h"
+#include "nsIContentPolicy.h"
+#include "nsIContentSecurityPolicy.h"
+#include "nsICookieJarSettings.h"
+#include "nsIDocShell.h"
+#include "nsIHttpChannel.h"
+#include "nsIHttpChannelInternal.h"
+#include "nsIIOService.h"
+#include "nsIOService.h"
+#include "nsIPrincipal.h"
+#include "nsIProtocolHandler.h"
+#include "nsIScriptError.h"
+#include "nsIScriptSecurityManager.h"
+#include "nsIStreamListenerTee.h"
+#include "nsIThreadRetargetableRequest.h"
+#include "nsIURI.h"
+#include "nsIXPConnect.h"
+
+#include "jsapi.h"
+#include "jsfriendapi.h"
+#include "js/CompilationAndEvaluation.h"
+#include "js/Exception.h"
+#include "js/SourceText.h"
+#include "js/TypeDecls.h"
+#include "nsError.h"
+#include "nsComponentManagerUtils.h"
+#include "nsContentSecurityManager.h"
+#include "nsContentPolicyUtils.h"
+#include "nsContentUtils.h"
+#include "nsDocShellCID.h"
+#include "nsJSEnvironment.h"
+#include "nsNetUtil.h"
+#include "nsIPipe.h"
+#include "nsIOutputStream.h"
+#include "nsPrintfCString.h"
+#include "nsString.h"
+#include "nsTArray.h"
+#include "nsThreadUtils.h"
+#include "nsXPCOM.h"
+#include "xpcpublic.h"
+
+#include "mozilla/AntiTrackingUtils.h"
+#include "mozilla/ArrayAlgorithm.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Encoding.h"
+#include "mozilla/LoadContext.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/ipc/BackgroundUtils.h"
+#include "mozilla/dom/ClientChannelHelper.h"
+#include "mozilla/dom/ClientInfo.h"
+#include "mozilla/dom/Exceptions.h"
+#include "mozilla/dom/nsCSPService.h"
+#include "mozilla/dom/nsCSPUtils.h"
+#include "mozilla/dom/PerformanceStorage.h"
+#include "mozilla/dom/Response.h"
+#include "mozilla/dom/ReferrerInfo.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/dom/SerializedStackHolder.h"
+#include "mozilla/dom/workerinternals/CacheLoadHandler.h"
+#include "mozilla/dom/workerinternals/NetworkLoadHandler.h"
+#include "mozilla/dom/workerinternals/ScriptResponseHeaderProcessor.h"
+#include "mozilla/Result.h"
+#include "mozilla/ResultExtensions.h"
+#include "mozilla/StaticPrefs_browser.h"
+#include "mozilla/UniquePtr.h"
+#include "WorkerRunnable.h"
+#include "WorkerScope.h"
+
+#define MAX_CONCURRENT_SCRIPTS 1000
+
+using JS::loader::ScriptKind;
+using JS::loader::ScriptLoadRequest;
+using mozilla::ipc::PrincipalInfo;
+
+namespace mozilla::dom::workerinternals {
+namespace {
+
+nsresult ConstructURI(const nsAString& aScriptURL, nsIURI* baseURI,
+                      const mozilla::Encoding* aDocumentEncoding,
+                      nsIURI** aResult) {
+  nsresult rv;
+  // Only top level workers' main script use the document charset for the
+  // script uri encoding. Otherwise, default encoding (UTF-8) is applied.
+  if (aDocumentEncoding) {
+    nsAutoCString charset;
+    aDocumentEncoding->Name(charset);
+    rv = NS_NewURI(aResult, aScriptURL, charset.get(), baseURI);
+  } else {
+    rv = NS_NewURI(aResult, aScriptURL, nullptr, baseURI);
+  }
+
+  if (NS_FAILED(rv)) {
+    return NS_ERROR_DOM_SYNTAX_ERR;
+  }
+  return NS_OK;
+}
+
+nsresult ChannelFromScriptURL(
+    nsIPrincipal* principal, Document* parentDoc, WorkerPrivate* aWorkerPrivate,
+    nsILoadGroup* loadGroup, nsIIOService* ios,
+    nsIScriptSecurityManager* secMan, nsIURI* aScriptURL,
+    const Maybe<ClientInfo>& aClientInfo,
+    const Maybe<ServiceWorkerDescriptor>& aController, bool aIsMainScript,
+    WorkerScriptType aWorkerScriptType, nsContentPolicyType aContentPolicyType,
+    nsLoadFlags aLoadFlags, uint32_t aSecFlags,
+    nsICookieJarSettings* aCookieJarSettings, nsIReferrerInfo* aReferrerInfo,
+    nsIChannel** aChannel) {
+  AssertIsOnMainThread();
+
+  nsresult rv;
+  nsCOMPtr<nsIURI> uri = aScriptURL;
+
+  // Only use the document when its principal matches the principal of the
+  // current request. This means scripts fetched using the Workers' own
+  // principal won't inherit properties of the document, in particular the CSP.
+  if (parentDoc && parentDoc->NodePrincipal() != principal) {
+    parentDoc = nullptr;
+  }
+
+  // The main service worker script should never be loaded over the network
+  // in this path.  It should always be offlined by ServiceWorkerScriptCache.
+  // We assert here since this error should also be caught by the runtime
+  // check in CacheLoadHandler.
+  //
+  // Note, if we ever allow service worker scripts to be loaded from network
+  // here we need to configure the channel properly.  For example, it must
+  // not allow redirects.
+  MOZ_DIAGNOSTIC_ASSERT(aContentPolicyType !=
+                        nsIContentPolicy::TYPE_INTERNAL_SERVICE_WORKER);
+
+  nsCOMPtr<nsIChannel> channel;
+  if (parentDoc) {
+    // This is the path for top level dedicated worker scripts with a document
+    rv = NS_NewChannel(getter_AddRefs(channel), uri, parentDoc, aSecFlags,
+                       aContentPolicyType,
+                       nullptr,  // aPerformanceStorage
+                       loadGroup,
+                       nullptr,  // aCallbacks
+                       aLoadFlags, ios);
+    NS_ENSURE_SUCCESS(rv, NS_ERROR_DOM_SECURITY_ERR);
+  } else {
+    // This branch is used in the following cases:
+    //    * Shared and ServiceWorkers (who do not have a doc)
+    //    * Static Module Imports
+    //    * ImportScripts
+
+    // We must have a loadGroup with a load context for the principal to
+    // traverse the channel correctly.
+
+    MOZ_ASSERT(loadGroup);
+    MOZ_ASSERT(NS_LoadGroupMatchesPrincipal(loadGroup, principal));
+
+    RefPtr<PerformanceStorage> performanceStorage;
+    nsCOMPtr<nsICSPEventListener> cspEventListener;
+    if (aWorkerPrivate && !aIsMainScript) {
+      performanceStorage = aWorkerPrivate->GetPerformanceStorage();
+      cspEventListener = aWorkerPrivate->CSPEventListener();
+    }
+
+    if (aClientInfo.isSome()) {
+      // If we have an existing clientInfo (true for all modules and
+      // importScripts), we will use this branch
+      rv = NS_NewChannel(getter_AddRefs(channel), uri, principal,
+                         aClientInfo.ref(), aController, aSecFlags,
+                         aContentPolicyType, aCookieJarSettings,
+                         performanceStorage, loadGroup, nullptr,  // aCallbacks
+                         aLoadFlags, ios);
+    } else {
+      rv = NS_NewChannel(getter_AddRefs(channel), uri, principal, aSecFlags,
+                         aContentPolicyType, aCookieJarSettings,
+                         performanceStorage, loadGroup, nullptr,  // aCallbacks
+                         aLoadFlags, ios);
+    }
+
+    NS_ENSURE_SUCCESS(rv, NS_ERROR_DOM_SECURITY_ERR);
+
+    if (cspEventListener) {
+      nsCOMPtr<nsILoadInfo> loadInfo = channel->LoadInfo();
+      rv = loadInfo->SetCspEventListener(cspEventListener);
+      NS_ENSURE_SUCCESS(rv, rv);
+    }
+  }
+
+  if (aReferrerInfo) {
+    nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(channel);
+    if (httpChannel) {
+      rv = httpChannel->SetReferrerInfo(aReferrerInfo);
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        return rv;
+      }
+    }
+  }
+
+  channel.forget(aChannel);
+  return rv;
+}
+
+void LoadAllScripts(WorkerPrivate* aWorkerPrivate,
+                    UniquePtr<SerializedStackHolder> aOriginStack,
+                    const nsTArray<nsString>& aScriptURLs, bool aIsMainScript,
+                    WorkerScriptType aWorkerScriptType, ErrorResult& aRv,
+                    const mozilla::Encoding* aDocumentEncoding = nullptr) {
+  aWorkerPrivate->AssertIsOnWorkerThread();
+  NS_ASSERTION(!aScriptURLs.IsEmpty(), "Bad arguments!");
+
+  AutoSyncLoopHolder syncLoop(aWorkerPrivate, Canceling);
+  nsCOMPtr<nsISerialEventTarget> syncLoopTarget =
+      syncLoop.GetSerialEventTarget();
+  if (!syncLoopTarget) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+
+  RefPtr<loader::WorkerScriptLoader> loader =
+      new loader::WorkerScriptLoader(aWorkerPrivate, std::move(aOriginStack),
+                                     syncLoopTarget, aWorkerScriptType, aRv);
+
+  if (NS_WARN_IF(aRv.Failed())) {
+    return;
+  }
+
+  bool ok = loader->CreateScriptRequests(aScriptURLs, aDocumentEncoding,
+                                         aIsMainScript);
+
+  if (!ok) {
+    return;
+  }
+  // Bug 1817259 - For now, we force loading the debugger script as Classic,
+  // even if the debugged worker is a Module.
+  if (aWorkerPrivate->WorkerType() == WorkerType::Module &&
+      aWorkerScriptType != DebuggerScript) {
+    if (!StaticPrefs::dom_workers_modules_enabled()) {
+      aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+      return;
+    }
+    MOZ_ASSERT(aIsMainScript);
+    // Module Load
+    RefPtr<JS::loader::ScriptLoadRequest> mainScript = loader->GetMainScript();
+    if (mainScript && mainScript->IsModuleRequest()) {
+      if (NS_FAILED(mainScript->AsModuleRequest()->StartModuleLoad())) {
+        return;
+      }
+      syncLoop.Run();
+      return;
+    }
+  }
+
+  if (loader->DispatchLoadScripts()) {
+    syncLoop.Run();
+  }
+}
+
+class ChannelGetterRunnable final : public WorkerMainThreadRunnable {
+  const nsAString& mScriptURL;
+  const WorkerType& mWorkerType;
+  const RequestCredentials& mCredentials;
+  const ClientInfo mClientInfo;
+  WorkerLoadInfo& mLoadInfo;
+  nsresult mResult;
+
+ public:
+  ChannelGetterRunnable(WorkerPrivate* aParentWorker,
+                        const nsAString& aScriptURL,
+                        const WorkerType& aWorkerType,
+                        const RequestCredentials& aCredentials,
+                        WorkerLoadInfo& aLoadInfo)
+      : WorkerMainThreadRunnable(aParentWorker,
+                                 "ScriptLoader :: ChannelGetter"_ns),
+        mScriptURL(aScriptURL)
+        // ClientInfo should always be present since this should not be called
+        // if parent's status is greater than Running.
+        ,
+        mWorkerType(aWorkerType),
+        mCredentials(aCredentials),
+        mClientInfo(aParentWorker->GlobalScope()->GetClientInfo().ref()),
+        mLoadInfo(aLoadInfo),
+        mResult(NS_ERROR_FAILURE) {
+    MOZ_ASSERT(aParentWorker);
+    aParentWorker->AssertIsOnWorkerThread();
+  }
+
+  virtual bool MainThreadRun() override {
+    AssertIsOnMainThread();
+
+    // Initialize the WorkerLoadInfo principal to our triggering principal
+    // before doing anything else.  Normally we do this in the WorkerPrivate
+    // Constructor, but we can't do so off the main thread when creating
+    // a nested worker.  So do it here instead.
+    mLoadInfo.mLoadingPrincipal = mWorkerPrivate->GetPrincipal();
+    MOZ_DIAGNOSTIC_ASSERT(mLoadInfo.mLoadingPrincipal);
+
+    mLoadInfo.mPrincipal = mLoadInfo.mLoadingPrincipal;
+
+    // Figure out our base URI.
+    nsCOMPtr<nsIURI> baseURI = mWorkerPrivate->GetBaseURI();
+    MOZ_ASSERT(baseURI);
+
+    // May be null.
+    nsCOMPtr<Document> parentDoc = mWorkerPrivate->GetDocument();
+
+    mLoadInfo.mLoadGroup = mWorkerPrivate->GetLoadGroup();
+    mLoadInfo.mCookieJarSettings = mWorkerPrivate->CookieJarSettings();
+
+    // Nested workers use default uri encoding.
+    nsCOMPtr<nsIURI> url;
+    mResult = ConstructURI(mScriptURL, baseURI, nullptr, getter_AddRefs(url));
+    NS_ENSURE_SUCCESS(mResult, true);
+
+    Maybe<ClientInfo> clientInfo;
+    clientInfo.emplace(mClientInfo);
+
+    nsCOMPtr<nsIChannel> channel;
+    nsCOMPtr<nsIReferrerInfo> referrerInfo =
+        ReferrerInfo::CreateForFetch(mLoadInfo.mLoadingPrincipal, nullptr);
+    mLoadInfo.mReferrerInfo =
+        static_cast<ReferrerInfo*>(referrerInfo.get())
+            ->CloneWithNewPolicy(mWorkerPrivate->GetReferrerPolicy());
+
+    mResult = workerinternals::ChannelFromScriptURLMainThread(
+        mLoadInfo.mLoadingPrincipal, parentDoc, mLoadInfo.mLoadGroup, url,
+        mWorkerType, mCredentials, clientInfo,
+        // Nested workers are always dedicated.
+        nsIContentPolicy::TYPE_INTERNAL_WORKER, mLoadInfo.mCookieJarSettings,
+        mLoadInfo.mReferrerInfo, getter_AddRefs(channel));
+    NS_ENSURE_SUCCESS(mResult, true);
+
+    mResult = mLoadInfo.SetPrincipalsAndCSPFromChannel(channel);
+    NS_ENSURE_SUCCESS(mResult, true);
+
+    mLoadInfo.mChannel = std::move(channel);
+    return true;
+  }
+
+  nsresult GetResult() const { return mResult; }
+
+ private:
+  virtual ~ChannelGetterRunnable() = default;
+};
+
+nsresult GetCommonSecFlags(bool aIsMainScript, nsIURI* uri,
+                           nsIPrincipal* principal,
+                           WorkerScriptType aWorkerScriptType,
+                           uint32_t& secFlags) {
+  bool inheritAttrs = nsContentUtils::ChannelShouldInheritPrincipal(
+      principal, uri, true /* aInheritForAboutBlank */,
+      false /* aForceInherit */);
+
+  bool isData = uri->SchemeIs("data");
+  if (inheritAttrs && !isData) {
+    secFlags |= nsILoadInfo::SEC_FORCE_INHERIT_PRINCIPAL;
+  }
+
+  if (aWorkerScriptType == DebuggerScript) {
+    // A DebuggerScript needs to be a local resource like chrome: or resource:
+    bool isUIResource = false;
+    nsresult rv = NS_URIChainHasFlags(
+        uri, nsIProtocolHandler::URI_IS_UI_RESOURCE, &isUIResource);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    if (!isUIResource) {
+      return NS_ERROR_DOM_SECURITY_ERR;
+    }
+
+    secFlags |= nsILoadInfo::SEC_ALLOW_CHROME;
+  }
+
+  // Note: this is for backwards compatibility and goes against spec.
+  // We should find a better solution.
+  if (aIsMainScript && isData) {
+    secFlags = nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_SEC_CONTEXT_IS_NULL;
+  }
+
+  return NS_OK;
+}
+
+nsresult GetModuleSecFlags(bool aIsTopLevel, nsIPrincipal* principal,
+                           WorkerScriptType aWorkerScriptType, nsIURI* aURI,
+                           RequestCredentials aCredentials,
+                           uint32_t& secFlags) {
+  // Implements "To fetch a single module script,"
+  // Step 9. If destination is "worker", "sharedworker", or "serviceworker",
+  //         and the top-level module fetch flag is set, then set request's
+  //         mode to "same-origin".
+  secFlags = aIsTopLevel
+                 ? nsILoadInfo::SEC_REQUIRE_SAME_ORIGIN_DATA_IS_BLOCKED
+                 : nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_INHERITS_SEC_CONTEXT;
+
+  // Step 8. Let request be a new request whose [...] mode is "cors" [...]
+  // This implements the same Cookie settings as  nsContentSecurityManager's
+  // ComputeSecurityFlags. The main difference is the line above, Step 9,
+  // setting to same origin.
+  if (aCredentials == RequestCredentials::Include) {
+    secFlags |= nsILoadInfo::nsILoadInfo::SEC_COOKIES_INCLUDE;
+  } else if (aCredentials == RequestCredentials::Same_origin) {
+    secFlags |= nsILoadInfo::nsILoadInfo::SEC_COOKIES_SAME_ORIGIN;
+  } else if (aCredentials == RequestCredentials::Omit) {
+    secFlags |= nsILoadInfo::nsILoadInfo::SEC_COOKIES_OMIT;
+  }
+
+  return GetCommonSecFlags(aIsTopLevel, aURI, principal, aWorkerScriptType,
+                           secFlags);
+}
+
+nsresult GetClassicSecFlags(bool aIsMainScript, nsIURI* uri,
+                            nsIPrincipal* principal,
+                            WorkerScriptType aWorkerScriptType,
+                            uint32_t& secFlags) {
+  secFlags = aIsMainScript
+                 ? nsILoadInfo::SEC_REQUIRE_SAME_ORIGIN_DATA_IS_BLOCKED
+                 : nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_INHERITS_SEC_CONTEXT;
+
+  return GetCommonSecFlags(aIsMainScript, uri, principal, aWorkerScriptType,
+                           secFlags);
+}
+
+}  //  anonymous namespace
+
+namespace loader {
+
+class ScriptExecutorRunnable final : public MainThreadWorkerSyncRunnable {
+  RefPtr<WorkerScriptLoader> mScriptLoader;
+  const Span<RefPtr<ThreadSafeRequestHandle>> mLoadedRequests;
+
+ public:
+  ScriptExecutorRunnable(WorkerScriptLoader* aScriptLoader,
+                         WorkerPrivate* aWorkerPrivate,
+                         nsISerialEventTarget* aSyncLoopTarget,
+                         Span<RefPtr<ThreadSafeRequestHandle>> aLoadedRequests);
+
+ private:
+  ~ScriptExecutorRunnable() = default;
+
+  virtual bool IsDebuggerRunnable() const override;
+
+  virtual bool PreRun(WorkerPrivate* aWorkerPrivate) override;
+
+  bool ProcessModuleScript(JSContext* aCx, WorkerPrivate* aWorkerPrivate);
+
+  bool ProcessClassicScripts(JSContext* aCx, WorkerPrivate* aWorkerPrivate);
+
+  virtual bool WorkerRun(JSContext* aCx,
+                         WorkerPrivate* aWorkerPrivate) override;
+
+  nsresult Cancel() override;
+};
+
+template <typename Unit>
+static bool EvaluateSourceBuffer(JSContext* aCx,
+                                 const JS::CompileOptions& aOptions,
+                                 JS::loader::ClassicScript* aClassicScript,
+                                 JS::SourceText<Unit>& aSourceBuffer) {
+  static_assert(std::is_same<Unit, char16_t>::value ||
+                    std::is_same<Unit, Utf8Unit>::value,
+                "inferred units must be UTF-8 or UTF-16");
+
+  JS::Rooted<JSScript*> script(aCx, JS::Compile(aCx, aOptions, aSourceBuffer));
+
+  if (!script) {
+    return false;
+  }
+
+  if (aClassicScript) {
+    aClassicScript->AssociateWithScript(script);
+  }
+
+  JS::Rooted<JS::Value> unused(aCx);
+  return JS_ExecuteScript(aCx, script, &unused);
+}
+
+WorkerScriptLoader::WorkerScriptLoader(
+    WorkerPrivate* aWorkerPrivate,
+    UniquePtr<SerializedStackHolder> aOriginStack,
+    nsISerialEventTarget* aSyncLoopTarget, WorkerScriptType aWorkerScriptType,
+    ErrorResult& aRv)
+    : mOriginStack(std::move(aOriginStack)),
+      mSyncLoopTarget(aSyncLoopTarget),
+      mWorkerScriptType(aWorkerScriptType),
+      mRv(aRv),
+      mLoadingModuleRequestCount(0),
+      mCleanedUp(false),
+      mCleanUpLock("cleanUpLock") {
+  aWorkerPrivate->AssertIsOnWorkerThread();
+
+  RefPtr<StrongWorkerRef> workerRef =
+      StrongWorkerRef::Create(aWorkerPrivate, "ScriptLoader");
+
+  if (workerRef) {
+    mWorkerRef = new ThreadSafeWorkerRef(workerRef);
+  } else {
+    mRv.Throw(NS_ERROR_FAILURE);
+    return;
+  }
+
+  nsIGlobalObject* global = GetGlobal();
+  mController = global->GetController();
+
+  if (!StaticPrefs::dom_workers_modules_enabled()) {
+    return;
+  }
+
+  // Set up the module loader, if it has not been initialzied yet.
+  if (!aWorkerPrivate->IsServiceWorker()) {
+    InitModuleLoader();
+  }
+}
+
+ScriptLoadRequest* WorkerScriptLoader::GetMainScript() {
+  mWorkerRef->Private()->AssertIsOnWorkerThread();
+  ScriptLoadRequest* request = mLoadingRequests.getFirst();
+  if (request->GetWorkerLoadContext()->IsTopLevel()) {
+    return request;
+  }
+  return nullptr;
+}
+
+void WorkerScriptLoader::InitModuleLoader() {
+  mWorkerRef->Private()->AssertIsOnWorkerThread();
+  if (GetGlobal()->GetModuleLoader(nullptr)) {
+    return;
+  }
+  RefPtr<WorkerModuleLoader> moduleLoader =
+      new WorkerModuleLoader(this, GetGlobal(), mSyncLoopTarget.get());
+  if (mWorkerScriptType == WorkerScript) {
+    mWorkerRef->Private()->GlobalScope()->InitModuleLoader(moduleLoader);
+    return;
+  }
+  mWorkerRef->Private()->DebuggerGlobalScope()->InitModuleLoader(moduleLoader);
+}
+
+bool WorkerScriptLoader::CreateScriptRequests(
+    const nsTArray<nsString>& aScriptURLs,
+    const mozilla::Encoding* aDocumentEncoding, bool aIsMainScript) {
+  mWorkerRef->Private()->AssertIsOnWorkerThread();
+  // If a worker has been loaded as a module worker, ImportScripts calls are
+  // disallowed -- then the operation is invalid.
+  //
+  // 10.3.1 Importing scripts and libraries.
+  // Step 1. If worker global scope's type is "module", throw a TypeError
+  //         exception.
+  //
+  // Also, for now, the debugger script is always loaded as Classic,
+  // even if the debugged worker is a Module. We still want to allow
+  // it to use importScripts.
+  if (mWorkerRef->Private()->WorkerType() == WorkerType::Module &&
+      !aIsMainScript && !IsDebuggerScript()) {
+    // This should only run for non-main scripts, as only these are
+    // importScripts
+    mRv.ThrowTypeError(
+        "Using `ImportScripts` inside a Module Worker is "
+        "disallowed.");
+    return false;
+  }
+  for (const nsString& scriptURL : aScriptURLs) {
+    RefPtr<ScriptLoadRequest> request =
+        CreateScriptLoadRequest(scriptURL, aDocumentEncoding, aIsMainScript);
+    if (!request) {
+      return false;
+    }
+    mLoadingRequests.AppendElement(request);
+  }
+
+  return true;
+}
+
+nsTArray<RefPtr<ThreadSafeRequestHandle>> WorkerScriptLoader::GetLoadingList() {
+  mWorkerRef->Private()->AssertIsOnWorkerThread();
+  nsTArray<RefPtr<ThreadSafeRequestHandle>> list;
+  for (ScriptLoadRequest* req = mLoadingRequests.getFirst(); req;
+       req = req->getNext()) {
+    RefPtr<ThreadSafeRequestHandle> handle =
+        new ThreadSafeRequestHandle(req, mSyncLoopTarget.get());
+    list.AppendElement(handle.forget());
+  }
+  return list;
+}
+
+bool WorkerScriptLoader::IsDynamicImport(ScriptLoadRequest* aRequest) {
+  return aRequest->IsModuleRequest() &&
+         aRequest->AsModuleRequest()->IsDynamicImport();
+}
+
+nsContentPolicyType WorkerScriptLoader::GetContentPolicyType(
+    ScriptLoadRequest* aRequest) {
+  if (aRequest->GetWorkerLoadContext()->IsTopLevel()) {
+    // Implements https://html.spec.whatwg.org/#worker-processing-model
+    // Step 13: Let destination be "sharedworker" if is shared is true, and
+    // "worker" otherwise.
+    return mWorkerRef->Private()->ContentPolicyType();
+  }
+  if (aRequest->IsModuleRequest()) {
+    // Implements the destination for Step 14 in
+    // https://html.spec.whatwg.org/#worker-processing-model
+    //
+    // We need a special subresource type in order to correctly implement
+    // the graph fetch, where the destination is set to "worker" or
+    // "sharedworker".
+    return nsIContentPolicy::TYPE_INTERNAL_WORKER_STATIC_MODULE;
+  }
+  return nsIContentPolicy::TYPE_INTERNAL_WORKER_IMPORT_SCRIPTS;
+}
+
+already_AddRefed<ScriptLoadRequest> WorkerScriptLoader::CreateScriptLoadRequest(
+    const nsString& aScriptURL, const mozilla::Encoding* aDocumentEncoding,
+    bool aIsMainScript) {
+  mWorkerRef->Private()->AssertIsOnWorkerThread();
+  WorkerLoadContext::Kind kind =
+      WorkerLoadContext::GetKind(aIsMainScript, IsDebuggerScript());
+
+  Maybe<ClientInfo> clientInfo = GetGlobal()->GetClientInfo();
+
+  // (For non-serviceworkers, this variable does not matter, but false best
+  // captures their behavior.)
+  bool onlyExistingCachedResourcesAllowed = false;
+  if (mWorkerRef->Private()->IsServiceWorker()) {
+    // https://w3c.github.io/ServiceWorker/#importscripts step 4:
+    // > 4. If serviceWorker’s state is not "parsed" or "installing":
+    // >    1. Return map[url] if it exists and a network error otherwise.
+    //
+    // So if our state is beyond installing, it's too late to make a request
+    // that would perform a new fetch which would be cached.
+    onlyExistingCachedResourcesAllowed =
+        mWorkerRef->Private()->GetServiceWorkerDescriptor().State() >
+        ServiceWorkerState::Installing;
+  }
+  RefPtr<WorkerLoadContext> loadContext = new WorkerLoadContext(
+      kind, clientInfo, this, onlyExistingCachedResourcesAllowed);
+
+  // Create ScriptLoadRequests for this WorkerScriptLoader
+  ReferrerPolicy referrerPolicy = mWorkerRef->Private()->GetReferrerPolicy();
+
+  // Only top level workers' main script use the document charset for the
+  // script uri encoding. Otherwise, default encoding (UTF-8) is applied.
+  MOZ_ASSERT_IF(bool(aDocumentEncoding),
+                aIsMainScript && !mWorkerRef->Private()->GetParent());
+  nsCOMPtr<nsIURI> baseURI = aIsMainScript ? GetInitialBaseURI() : GetBaseURI();
+  nsCOMPtr<nsIURI> uri;
+  nsresult rv =
+      ConstructURI(aScriptURL, baseURI, aDocumentEncoding, getter_AddRefs(uri));
+  // If we failed to construct the URI, handle it in the LoadContext so it is
+  // thrown in the right order.
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    loadContext->mLoadResult = rv;
+  }
+
+  RefPtr<ScriptFetchOptions> fetchOptions =
+      new ScriptFetchOptions(CORSMode::CORS_NONE, referrerPolicy, nullptr);
+
+  RefPtr<ScriptLoadRequest> request = nullptr;
+  // Bug 1817259 - For now the debugger scripts are always loaded a Classic.
+  if (mWorkerRef->Private()->WorkerType() == WorkerType::Classic ||
+      IsDebuggerScript()) {
+    request = new ScriptLoadRequest(ScriptKind::eClassic, uri, fetchOptions,
+                                    SRIMetadata(), nullptr,  // mReferrer
+                                    loadContext);
+  } else {
+    // Implements part of "To fetch a worklet/module worker script graph"
+    // including, setting up the request with a credentials mode,
+    // destination.
+
+    // Step 1. Let options be a script fetch options.
+    // We currently don't track credentials in our ScriptFetchOptions
+    // implementation, so we are defaulting the fetchOptions object defined
+    // above. This behavior is handled fully in GetModuleSecFlags.
+
+    if (!StaticPrefs::dom_workers_modules_enabled()) {
+      mRv.ThrowTypeError("Modules in workers are currently disallowed.");
+      return nullptr;
+    }
+    RefPtr<WorkerModuleLoader::ModuleLoaderBase> moduleLoader =
+        GetGlobal()->GetModuleLoader(nullptr);
+
+    // Implements the referrer for "To fetch a single module script"
+    // Our implementation does not have a "client" as a referrer.
+    // However, when client is resolved (per 8.3. Determine request’s
+    // Referrer in
+    // https://w3c.github.io/webappsec-referrer-policy/#determine-requests-referrer)
+    // This should result in the referrer source being the creation URL.
+    //
+    // In subresource modules, the referrer is the importing script.
+    nsCOMPtr<nsIURI> referrer =
+        mWorkerRef->Private()->GetReferrerInfo()->GetOriginalReferrer();
+
+    // Part of Step 2. This sets the Top-level flag to true
+    request = new ModuleLoadRequest(
+        uri, fetchOptions, SRIMetadata(), referrer, loadContext,
+        true,  /* is top level */
+        false, /* is dynamic import */
+        moduleLoader, ModuleLoadRequest::NewVisitedSetForTopLevelImport(uri),
+        nullptr);
+  }
+
+  // Set the mURL, it will be used for error handling and debugging.
+  request->mURL = NS_ConvertUTF16toUTF8(aScriptURL);
+
+  return request.forget();
+}
+
+bool WorkerScriptLoader::DispatchLoadScript(ScriptLoadRequest* aRequest) {
+  mWorkerRef->Private()->AssertIsOnWorkerThread();
+
+  IncreaseLoadingModuleRequestCount();
+
+  nsTArray<RefPtr<ThreadSafeRequestHandle>> scriptLoadList;
+  RefPtr<ThreadSafeRequestHandle> handle =
+      new ThreadSafeRequestHandle(aRequest, mSyncLoopTarget.get());
+  scriptLoadList.AppendElement(handle.forget());
+
+  RefPtr<ScriptLoaderRunnable> runnable =
+      new ScriptLoaderRunnable(this, std::move(scriptLoadList));
+
+  RefPtr<StrongWorkerRef> workerRef = StrongWorkerRef::Create(
+      mWorkerRef->Private(), "ScriptLoader", [runnable]() {
+        NS_DispatchToMainThread(NewRunnableMethod(
+            "ScriptLoaderRunnable::CancelMainThreadWithBindingAborted",
+            runnable,
+            &ScriptLoaderRunnable::CancelMainThreadWithBindingAborted));
+      });
+
+  if (NS_FAILED(NS_DispatchToMainThread(runnable))) {
+    NS_ERROR("Failed to dispatch!");
+    mRv.Throw(NS_ERROR_FAILURE);
+    return false;
+  }
+  return true;
+}
+
+bool WorkerScriptLoader::DispatchLoadScripts() {
+  mWorkerRef->Private()->AssertIsOnWorkerThread();
+
+  nsTArray<RefPtr<ThreadSafeRequestHandle>> scriptLoadList = GetLoadingList();
+
+  RefPtr<ScriptLoaderRunnable> runnable =
+      new ScriptLoaderRunnable(this, std::move(scriptLoadList));
+
+  RefPtr<StrongWorkerRef> workerRef = StrongWorkerRef::Create(
+      mWorkerRef->Private(), "ScriptLoader", [runnable]() {
+        NS_DispatchToMainThread(NewRunnableMethod(
+            "ScriptLoaderRunnable::CancelMainThreadWithBindingAborted",
+            runnable,
+            &ScriptLoaderRunnable::CancelMainThreadWithBindingAborted));
+      });
+
+  if (NS_FAILED(NS_DispatchToMainThread(runnable))) {
+    NS_ERROR("Failed to dispatch!");
+    mRv.Throw(NS_ERROR_FAILURE);
+    return false;
+  }
+  return true;
+}
+
+nsIURI* WorkerScriptLoader::GetInitialBaseURI() {
+  MOZ_ASSERT(mWorkerRef->Private());
+  nsIURI* baseURI;
+  WorkerPrivate* parentWorker = mWorkerRef->Private()->GetParent();
+  if (parentWorker) {
+    baseURI = parentWorker->GetBaseURI();
+  } else {
+    // May be null.
+    baseURI = mWorkerRef->Private()->GetBaseURI();
+  }
+
+  return baseURI;
+}
+
+nsIURI* WorkerScriptLoader::GetBaseURI() const {
+  MOZ_ASSERT(mWorkerRef);
+  nsIURI* baseURI;
+  baseURI = mWorkerRef->Private()->GetBaseURI();
+  NS_ASSERTION(baseURI, "Should have been set already!");
+
+  return baseURI;
+}
+
+nsIGlobalObject* WorkerScriptLoader::GetGlobal() {
+  mWorkerRef->Private()->AssertIsOnWorkerThread();
+  return mWorkerScriptType == WorkerScript
+             ? static_cast<nsIGlobalObject*>(
+                   mWorkerRef->Private()->GlobalScope())
+             : mWorkerRef->Private()->DebuggerGlobalScope();
+}
+
+void WorkerScriptLoader::MaybeMoveToLoadedList(ScriptLoadRequest* aRequest) {
+  mWorkerRef->Private()->AssertIsOnWorkerThread();
+  // Only set to ready for regular scripts. Module loader will set the script to
+  // ready if it is a Module Request.
+  if (!aRequest->IsModuleRequest()) {
+    aRequest->SetReady();
+  }
+
+  // If the request is not in a list, we are in an illegal state.
+  MOZ_RELEASE_ASSERT(aRequest->isInList());
+
+  while (!mLoadingRequests.isEmpty()) {
+    ScriptLoadRequest* request = mLoadingRequests.getFirst();
+    // We need to move requests in post order. If prior requests have not
+    // completed, delay execution.
+    if (!request->IsReadyToRun()) {
+      break;
+    }
+
+    RefPtr<ScriptLoadRequest> req = mLoadingRequests.Steal(request);
+    mLoadedRequests.AppendElement(req);
+  }
+}
+
+bool WorkerScriptLoader::StoreCSP() {
+  // We must be on the same worker as we started on.
+  mWorkerRef->Private()->AssertIsOnWorkerThread();
+
+  if (!mWorkerRef->Private()->GetJSContext()) {
+    return false;
+  }
+
+  MOZ_ASSERT(!mRv.Failed());
+
+  // Move the CSP from the workerLoadInfo in the corresponding Client
+  // where the CSP code expects it!
+  mWorkerRef->Private()->StoreCSPOnClient();
+  return true;
+}
+
+bool WorkerScriptLoader::ProcessPendingRequests(JSContext* aCx) {
+  mWorkerRef->Private()->AssertIsOnWorkerThread();
+  // Don't run if something else has already failed.
+  if (mExecutionAborted) {
+    mLoadedRequests.CancelRequestsAndClear();
+    TryShutdown();
+    return true;
+  }
+
+  // If nothing else has failed, our ErrorResult better not be a failure
+  // either.
+  MOZ_ASSERT(!mRv.Failed(), "Who failed it and why?");
+
+  // Slightly icky action at a distance, but there's no better place to stash
+  // this value, really.
+  JS::Rooted<JSObject*> global(aCx, JS::CurrentGlobalOrNull(aCx));
+  MOZ_ASSERT(global);
+
+  while (!mLoadedRequests.isEmpty()) {
+    // Take a reference, but do not remove it from the list yet. There is a
+    // possibility that this will need to be cancelled.
+    RefPtr<ScriptLoadRequest> req = mLoadedRequests.getFirst();
+    // We don't have a ProcessRequest method (like we do on the DOM), as there
+    // isn't much processing that we need to do per request that isn't related
+    // to evaluation (the processsing done for the DOM is handled in
+    // DataRecievedFrom{Cache,Network} for workers.
+    // So, this inner loop calls EvaluateScript directly. This will change
+    // once modules are introduced as we will have some extra work to do.
+    if (!EvaluateScript(aCx, req)) {
+      mExecutionAborted = true;
+      WorkerLoadContext* loadContext = req->GetWorkerLoadContext();
+      mMutedErrorFlag = loadContext->mMutedErrorFlag.valueOr(true);
+      mLoadedRequests.CancelRequestsAndClear();
+      break;
+    }
+    // remove the element from the list.
+    mLoadedRequests.Remove(req);
+  }
+
+  TryShutdown();
+  return true;
+}
+
+nsresult WorkerScriptLoader::LoadScript(
+    ThreadSafeRequestHandle* aRequestHandle) {
+  AssertIsOnMainThread();
+
+  WorkerLoadContext* loadContext = aRequestHandle->GetContext();
+  ScriptLoadRequest* request = aRequestHandle->GetRequest();
+  MOZ_ASSERT_IF(loadContext->IsTopLevel(), !IsDebuggerScript());
+
+  // The URL passed to us for loading was invalid, stop loading at this point.
+  if (loadContext->mLoadResult != NS_ERROR_NOT_INITIALIZED) {
+    return loadContext->mLoadResult;
+  }
+
+  WorkerPrivate* parentWorker = mWorkerRef->Private()->GetParent();
+
+  // For JavaScript debugging, the devtools server must run on the same
+  // thread as the debuggee, indicating the worker uses content principal.
+  // However, in Bug 863246, web content will no longer be able to load
+  // resource:// URIs by default, so we need system principal to load
+  // debugger scripts.
+  nsIPrincipal* principal = (IsDebuggerScript())
+                                ? nsContentUtils::GetSystemPrincipal()
+                                : mWorkerRef->Private()->GetPrincipal();
+
+  nsCOMPtr<nsILoadGroup> loadGroup = mWorkerRef->Private()->GetLoadGroup();
+  MOZ_DIAGNOSTIC_ASSERT(principal);
+
+  NS_ENSURE_TRUE(NS_LoadGroupMatchesPrincipal(loadGroup, principal),
+                 NS_ERROR_FAILURE);
+
+  // May be null.
+  nsCOMPtr<Document> parentDoc = mWorkerRef->Private()->GetDocument();
+
+  nsCOMPtr<nsIChannel> channel;
+  if (loadContext->IsTopLevel()) {
+    // May be null.
+    channel = mWorkerRef->Private()->ForgetWorkerChannel();
+  }
+
+  nsCOMPtr<nsIIOService> ios(do_GetIOService());
+
+  nsIScriptSecurityManager* secMan = nsContentUtils::GetSecurityManager();
+  NS_ASSERTION(secMan, "This should never be null!");
+
+  nsresult& rv = loadContext->mLoadResult;
+
+  nsLoadFlags loadFlags = mWorkerRef->Private()->GetLoadFlags();
+
+  // Get the top-level worker.
+  WorkerPrivate* topWorkerPrivate = mWorkerRef->Private();
+  WorkerPrivate* parent = topWorkerPrivate->GetParent();
+  while (parent) {
+    topWorkerPrivate = parent;
+    parent = topWorkerPrivate->GetParent();
+  }
+
+  // If the top-level worker is a dedicated worker and has a window, and the
+  // window has a docshell, the caching behavior of this worker should match
+  // that of that docshell.
+  if (topWorkerPrivate->IsDedicatedWorker()) {
+    nsCOMPtr<nsPIDOMWindowInner> window = topWorkerPrivate->GetWindow();
+    if (window) {
+      nsCOMPtr<nsIDocShell> docShell = window->GetDocShell();
+      if (docShell) {
+        nsresult rv = docShell->GetDefaultLoadFlags(&loadFlags);
+        NS_ENSURE_SUCCESS(rv, rv);
+      }
+    }
+  }
+
+  if (!channel) {
+    nsCOMPtr<nsIReferrerInfo> referrerInfo;
+    uint32_t secFlags;
+    if (request->IsModuleRequest()) {
+      // https://fetch.spec.whatwg.org/#concept-main-fetch
+      // Step 8. If request’s referrer policy is the empty string, then set
+      //         request’s referrer policy to request’s policy container’s
+      //         referrer policy.
+      ReferrerPolicy policy =
+          request->ReferrerPolicy() == ReferrerPolicy::_empty
+              ? mWorkerRef->Private()->GetReferrerPolicy()
+              : request->ReferrerPolicy();
+
+      referrerInfo = new ReferrerInfo(request->mReferrer, policy);
+      rv = GetModuleSecFlags(
+          loadContext->IsTopLevel(), principal, mWorkerScriptType,
+          request->mURI, mWorkerRef->Private()->WorkerCredentials(), secFlags);
+    } else {
+      referrerInfo = ReferrerInfo::CreateForFetch(principal, nullptr);
+      if (parentWorker && !loadContext->IsTopLevel()) {
+        referrerInfo =
+            static_cast<ReferrerInfo*>(referrerInfo.get())
+                ->CloneWithNewPolicy(parentWorker->GetReferrerPolicy());
+      }
+      rv = GetClassicSecFlags(loadContext->IsTopLevel(), request->mURI,
+                              principal, mWorkerScriptType, secFlags);
+    }
+
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    nsContentPolicyType contentPolicyType = GetContentPolicyType(request);
+
+    rv = ChannelFromScriptURL(
+        principal, parentDoc, mWorkerRef->Private(), loadGroup, ios, secMan,
+        request->mURI, loadContext->mClientInfo, mController,
+        loadContext->IsTopLevel(), mWorkerScriptType, contentPolicyType,
+        loadFlags, secFlags, mWorkerRef->Private()->CookieJarSettings(),
+        referrerInfo, getter_AddRefs(channel));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+  // Associate any originating stack with the channel.
+  if (!mOriginStackJSON.IsEmpty()) {
+    NotifyNetworkMonitorAlternateStack(channel, mOriginStackJSON);
+  }
+
+  // We need to know which index we're on in OnStreamComplete so we know
+  // where to put the result.
+  RefPtr<NetworkLoadHandler> listener =
+      new NetworkLoadHandler(this, aRequestHandle);
+
+  RefPtr<ScriptResponseHeaderProcessor> headerProcessor = nullptr;
+
+  // For each debugger script, a non-debugger script load of the same script
+  // should have occured prior that processed the headers.
+  if (!IsDebuggerScript()) {
+    headerProcessor = MakeRefPtr<ScriptResponseHeaderProcessor>(
+        mWorkerRef->Private(),
+        loadContext->IsTopLevel() && !IsDynamicImport(request),
+        GetContentPolicyType(request) ==
+            nsIContentPolicy::TYPE_INTERNAL_WORKER_IMPORT_SCRIPTS);
+  }
+
+  nsCOMPtr<nsIStreamLoader> loader;
+  rv = NS_NewStreamLoader(getter_AddRefs(loader), listener, headerProcessor);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    return rv;
+  }
+
+  if (loadContext->IsTopLevel()) {
+    MOZ_DIAGNOSTIC_ASSERT(loadContext->mClientInfo.isSome());
+
+    // In order to get the correct foreign partitioned prinicpal, we need to
+    // set the `IsThirdPartyContextToTopWindow` to the channel's loadInfo.
+    // This flag reflects the fact that if the worker is created under a
+    // third-party context.
+    nsCOMPtr<nsILoadInfo> loadInfo = channel->LoadInfo();
+    loadInfo->SetIsThirdPartyContextToTopWindow(
+        mWorkerRef->Private()->IsThirdPartyContextToTopWindow());
+
+    Maybe<ClientInfo> clientInfo;
+    clientInfo.emplace(loadContext->mClientInfo.ref());
+    rv = AddClientChannelHelper(channel, std::move(clientInfo),
+                                Maybe<ClientInfo>(),
+                                mWorkerRef->Private()->HybridEventTarget());
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+  if (StaticPrefs::browser_tabs_remote_useCrossOriginEmbedderPolicy()) {
+    nsILoadInfo::CrossOriginEmbedderPolicy respectedCOEP =
+        mWorkerRef->Private()->GetEmbedderPolicy();
+    if (mWorkerRef->Private()->IsDedicatedWorker() &&
+        respectedCOEP == nsILoadInfo::EMBEDDER_POLICY_NULL) {
+      respectedCOEP = mWorkerRef->Private()->GetOwnerEmbedderPolicy();
+    }
+
+    nsCOMPtr<nsILoadInfo> channelLoadInfo = channel->LoadInfo();
+    channelLoadInfo->SetLoadingEmbedderPolicy(respectedCOEP);
+  }
+
+  if (loadContext->mCacheStatus != WorkerLoadContext::ToBeCached) {
+    rv = channel->AsyncOpen(loader);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  } else {
+    nsCOMPtr<nsIOutputStream> writer;
+
+    // In case we return early.
+    loadContext->mCacheStatus = WorkerLoadContext::Cancel;
+
+    NS_NewPipe(getter_AddRefs(loadContext->mCacheReadStream),
+               getter_AddRefs(writer), 0,
+               UINT32_MAX,    // unlimited size to avoid writer WOULD_BLOCK case
+               true, false);  // non-blocking reader, blocking writer
+
+    nsCOMPtr<nsIStreamListenerTee> tee =
+        do_CreateInstance(NS_STREAMLISTENERTEE_CONTRACTID);
+    rv = tee->Init(loader, writer, listener);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+
+    nsresult rv = channel->AsyncOpen(tee);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return rv;
+    }
+  }
+
+  loadContext->mChannel.swap(channel);
+
+  return NS_OK;
+}
+
+nsresult WorkerScriptLoader::FillCompileOptionsForRequest(
+    JSContext* cx, ScriptLoadRequest* aRequest, JS::CompileOptions* aOptions,
+    JS::MutableHandle<JSScript*> aIntroductionScript) {
+  // The full URL shouldn't be exposed to the debugger. See Bug 1634872
+  aOptions->setFileAndLine(aRequest->mURL.get(), 1);
+  aOptions->setNoScriptRval(true);
+
+  aOptions->setMutedErrors(
+      aRequest->GetWorkerLoadContext()->mMutedErrorFlag.value());
+
+  if (aRequest->mSourceMapURL) {
+    aOptions->setSourceMapURL(aRequest->mSourceMapURL->get());
+  }
+
+  return NS_OK;
+}
+
+bool WorkerScriptLoader::EvaluateScript(JSContext* aCx,
+                                        ScriptLoadRequest* aRequest) {
+  mWorkerRef->Private()->AssertIsOnWorkerThread();
+  MOZ_ASSERT(!IsDynamicImport(aRequest));
+
+  WorkerLoadContext* loadContext = aRequest->GetWorkerLoadContext();
+
+  NS_ASSERTION(!loadContext->mChannel, "Should no longer have a channel!");
+  NS_ASSERTION(aRequest->IsReadyToRun(), "Should be scheduled!");
+
+  MOZ_ASSERT(!mRv.Failed(), "Who failed it and why?");
+  mRv.MightThrowJSException();
+  if (NS_FAILED(loadContext->mLoadResult)) {
+    ReportErrorToConsole(aRequest, loadContext->mLoadResult);
+    return false;
+  }
+
+  // If this is a top level script that succeeded, then mark the
+  // Client execution ready and possible controlled by a service worker.
+  if (loadContext->IsTopLevel()) {
+    if (mController.isSome()) {
+      MOZ_ASSERT(mWorkerScriptType == WorkerScript,
+                 "Debugger clients can't be controlled.");
+      mWorkerRef->Private()->GlobalScope()->Control(mController.ref());
+    }
+    mWorkerRef->Private()->ExecutionReady();
+  }
+
+  if (aRequest->IsModuleRequest()) {
+    // Only the top level module of the module graph will be executed from here,
+    // the rest will be executed from SpiderMonkey as part of the execution of
+    // the module graph.
+    MOZ_ASSERT(aRequest->IsTopLevel());
+    ModuleLoadRequest* request = aRequest->AsModuleRequest();
+    if (!request->mModuleScript) {
+      return false;
+    }
+
+    // Implements To fetch a worklet/module worker script graph
+    // Step 5. Fetch the descendants of and link result.
+    if (!request->InstantiateModuleGraph()) {
+      return false;
+    }
+
+    nsresult rv = request->EvaluateModule();
+    return NS_SUCCEEDED(rv);
+  }
+
+  JS::CompileOptions options(aCx);
+  // The introduction script is used by the DOM script loader as a way
+  // to fill the Debugger Metadata for the JS Execution context. We don't use
+  // the JS Execution context as we are not making use of async compilation
+  // (delegation to another worker to produce bytecode or compile a string to a
+  // JSScript), so it is not used in this context.
+  JS::Rooted<JSScript*> unusedIntroductionScript(aCx);
+  nsresult rv = FillCompileOptionsForRequest(aCx, aRequest, &options,
+                                             &unusedIntroductionScript);
+
+  MOZ_ASSERT(NS_SUCCEEDED(rv), "Filling compile options should not fail");
+
+  // Our ErrorResult still shouldn't be a failure.
+  MOZ_ASSERT(!mRv.Failed(), "Who failed it and why?");
+
+  // Get the source text.
+  ScriptLoadRequest::MaybeSourceText maybeSource;
+  rv = aRequest->GetScriptSource(aCx, &maybeSource);
+  if (NS_FAILED(rv)) {
+    mRv.StealExceptionFromJSContext(aCx);
+    return false;
+  }
+
+  RefPtr<JS::loader::ClassicScript> classicScript = nullptr;
+  if (StaticPrefs::dom_workers_modules_enabled() &&
+      !mWorkerRef->Private()->IsServiceWorker()) {
+    // We need a LoadedScript to be associated with the JSScript in order to
+    // correctly resolve the referencing private for dynamic imports. In turn
+    // this allows us to correctly resolve the BaseURL.
+    //
+    // Dynamic import is disallowed on service workers.  Additionally, causes
+    // crashes because the life cycle isn't completed for service workers.  To
+    // keep things simple, we don't create a classic script for ServiceWorkers.
+    // If this changes then we will need to ensure that the reference that is
+    // held is released appropriately.
+    nsCOMPtr<nsIURI> requestBaseURI;
+    if (loadContext->mMutedErrorFlag.valueOr(false)) {
+      NS_NewURI(getter_AddRefs(requestBaseURI), "about:blank"_ns);
+    } else {
+      requestBaseURI = aRequest->mBaseURL;
+    }
+    classicScript =
+        new JS::loader::ClassicScript(aRequest->mFetchOptions, requestBaseURI);
+  }
+
+  bool successfullyEvaluated =
+      aRequest->IsUTF8Text()
+          ? EvaluateSourceBuffer(aCx, options, classicScript,
+                                 maybeSource.ref<JS::SourceText<Utf8Unit>>())
+          : EvaluateSourceBuffer(aCx, options, classicScript,
+                                 maybeSource.ref<JS::SourceText<char16_t>>());
+
+  if (aRequest->IsCanceled()) {
+    return false;
+  }
+  if (!successfullyEvaluated) {
+    mRv.StealExceptionFromJSContext(aCx);
+    return false;
+  }
+  // steal the loadContext so that the cycle is broken and cycle collector can
+  // collect the scriptLoadRequest.
+  return true;
+}
+
+void WorkerScriptLoader::TryShutdown() {
+  if (AllScriptsExecuted() && AllModuleRequestsLoaded()) {
+    ShutdownScriptLoader(!mExecutionAborted, mMutedErrorFlag);
+  }
+}
+
+void WorkerScriptLoader::ShutdownScriptLoader(bool aResult, bool aMutedError) {
+  MOZ_ASSERT(AllScriptsExecuted());
+  MOZ_ASSERT(AllModuleRequestsLoaded());
+  mWorkerRef->Private()->AssertIsOnWorkerThread();
+
+  if (!aResult) {
+    // At this point there are two possibilities:
+    //
+    // 1) mRv.Failed().  In that case we just want to leave it
+    //    as-is, except if it has a JS exception and we need to mute JS
+    //    exceptions.  In that case, we log the exception without firing any
+    //    events and then replace it on the ErrorResult with a NetworkError,
+    //    per spec.
+    //
+    // 2) mRv succeeded.  As far as I can tell, this can only
+    //    happen when loading the main worker script and
+    //    GetOrCreateGlobalScope() fails or if ScriptExecutorRunnable::Cancel
+    //    got called.  Does it matter what we throw in this case?  I'm not
+    //    sure...
+    if (mRv.Failed()) {
+      if (aMutedError && mRv.IsJSException()) {
+        LogExceptionToConsole(mWorkerRef->Private()->GetJSContext(),
+                              mWorkerRef->Private());
+        mRv.Throw(NS_ERROR_DOM_NETWORK_ERR);
+      }
+    } else {
+      mRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    }
+  }
+
+  // Lock, shutdown, and cleanup state. After this the Loader is closed.
+  {
+    MutexAutoLock lock(CleanUpLock());
+
+    if (CleanedUp()) {
+      return;
+    }
+
+    mWorkerRef->Private()->AssertIsOnWorkerThread();
+    // Module loader doesn't use sync loop for dynamic import
+    if (mSyncLoopTarget) {
+      mWorkerRef->Private()->StopSyncLoop(mSyncLoopTarget,
+                                          aResult ? NS_OK : NS_ERROR_FAILURE);
+    }
+
+    // Signal cleanup
+    mCleanedUp = true;
+
+    // Allow worker shutdown.
+    mWorkerRef = nullptr;
+  }
+}
+
+void WorkerScriptLoader::ReportErrorToConsole(ScriptLoadRequest* aRequest,
+                                              nsresult aResult) const {
+  nsAutoString url = NS_ConvertUTF8toUTF16(aRequest->mURL);
+  workerinternals::ReportLoadError(mRv, aResult, url);
+}
+
+void WorkerScriptLoader::LogExceptionToConsole(JSContext* aCx,
+                                               WorkerPrivate* aWorkerPrivate) {
+  aWorkerPrivate->AssertIsOnWorkerThread();
+
+  MOZ_ASSERT(mRv.IsJSException());
+
+  JS::Rooted<JS::Value> exn(aCx);
+  if (!ToJSValue(aCx, std::move(mRv), &exn)) {
+    return;
+  }
+
+  // Now the exception state should all be in exn.
+  MOZ_ASSERT(!JS_IsExceptionPending(aCx));
+  MOZ_ASSERT(!mRv.Failed());
+
+  JS::ExceptionStack exnStack(aCx, exn, nullptr);
+  JS::ErrorReportBuilder report(aCx);
+  if (!report.init(aCx, exnStack, JS::ErrorReportBuilder::WithSideEffects)) {
+    JS_ClearPendingException(aCx);
+    return;
+  }
+
+  RefPtr<xpc::ErrorReport> xpcReport = new xpc::ErrorReport();
+  xpcReport->Init(report.report(), report.toStringResult().c_str(),
+                  aWorkerPrivate->IsChromeWorker(), aWorkerPrivate->WindowID());
+
+  RefPtr<AsyncErrorReporter> r = new AsyncErrorReporter(xpcReport);
+  NS_DispatchToMainThread(r);
+}
+
+bool WorkerScriptLoader::AllModuleRequestsLoaded() const {
+  mWorkerRef->Private()->AssertIsOnWorkerThread();
+  return mLoadingModuleRequestCount == 0;
+}
+
+void WorkerScriptLoader::IncreaseLoadingModuleRequestCount() {
+  mWorkerRef->Private()->AssertIsOnWorkerThread();
+  ++mLoadingModuleRequestCount;
+}
+
+void WorkerScriptLoader::DecreaseLoadingModuleRequestCount() {
+  mWorkerRef->Private()->AssertIsOnWorkerThread();
+  --mLoadingModuleRequestCount;
+}
+
+NS_IMPL_ISUPPORTS(ScriptLoaderRunnable, nsIRunnable, nsINamed)
+
+NS_IMPL_ISUPPORTS(WorkerScriptLoader, nsINamed)
+
+ScriptLoaderRunnable::ScriptLoaderRunnable(
+    WorkerScriptLoader* aScriptLoader,
+    nsTArray<RefPtr<ThreadSafeRequestHandle>> aLoadingRequests)
+    : mScriptLoader(aScriptLoader),
+      mWorkerRef(aScriptLoader->mWorkerRef),
+      mLoadingRequests(std::move(aLoadingRequests)),
+      mCancelMainThread(Nothing()) {
+  MOZ_ASSERT(aScriptLoader);
+}
+
+nsresult ScriptLoaderRunnable::Run() {
+  AssertIsOnMainThread();
+
+  // Convert the origin stack to JSON (which must be done on the main
+  // thread) explicitly, so that we can use the stack to notify the net
+  // monitor about every script we load. We do this, rather than pass
+  // the stack directly to the netmonitor, in order to be able to use this
+  // for all subsequent scripts.
+  if (mScriptLoader->mOriginStack &&
+      mScriptLoader->mOriginStackJSON.IsEmpty()) {
+    ConvertSerializedStackToJSON(std::move(mScriptLoader->mOriginStack),
+                                 mScriptLoader->mOriginStackJSON);
+  }
+
+  if (!mWorkerRef->Private()->IsServiceWorker() ||
+      mScriptLoader->IsDebuggerScript()) {
+    for (ThreadSafeRequestHandle* handle : mLoadingRequests) {
+      handle->mRunnable = this;
+    }
+
+    for (ThreadSafeRequestHandle* handle : mLoadingRequests) {
+      nsresult rv = mScriptLoader->LoadScript(handle);
+      if (NS_WARN_IF(NS_FAILED(rv))) {
+        LoadingFinished(handle, rv);
+        CancelMainThread(rv);
+        return rv;
+      }
+    }
+
+    return NS_OK;
+  }
+
+  MOZ_ASSERT(!mCacheCreator);
+  mCacheCreator = new CacheCreator(mWorkerRef->Private());
+
+  for (ThreadSafeRequestHandle* handle : mLoadingRequests) {
+    handle->mRunnable = this;
+    WorkerLoadContext* loadContext = handle->GetContext();
+    mCacheCreator->AddLoader(MakeNotNull<RefPtr<CacheLoadHandler>>(
+        mWorkerRef, handle, loadContext->IsTopLevel(),
+        loadContext->mOnlyExistingCachedResourcesAllowed, mScriptLoader));
+  }
+
+  // The worker may have a null principal on first load, but in that case its
+  // parent definitely will have one.
+  nsIPrincipal* principal = mWorkerRef->Private()->GetPrincipal();
+  if (!principal) {
+    WorkerPrivate* parentWorker = mWorkerRef->Private()->GetParent();
+    MOZ_ASSERT(parentWorker, "Must have a parent!");
+    principal = parentWorker->GetPrincipal();
+  }
+
+  nsresult rv = mCacheCreator->Load(principal);
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    CancelMainThread(rv);
+    return rv;
+  }
+
+  return NS_OK;
+}
+
+nsresult ScriptLoaderRunnable::OnStreamComplete(
+    ThreadSafeRequestHandle* aRequestHandle, nsresult aStatus) {
+  AssertIsOnMainThread();
+
+  LoadingFinished(aRequestHandle, aStatus);
+  return NS_OK;
+}
+
+void ScriptLoaderRunnable::LoadingFinished(
+    ThreadSafeRequestHandle* aRequestHandle, nsresult aRv) {
+  AssertIsOnMainThread();
+
+  WorkerLoadContext* loadContext = aRequestHandle->GetContext();
+
+  loadContext->mLoadResult = aRv;
+  MOZ_ASSERT(!loadContext->mLoadingFinished);
+  loadContext->mLoadingFinished = true;
+
+  if (loadContext->IsTopLevel() && NS_SUCCEEDED(aRv)) {
+    MOZ_DIAGNOSTIC_ASSERT(
+        mWorkerRef->Private()->PrincipalURIMatchesScriptURL());
+  }
+
+  MaybeExecuteFinishedScripts(aRequestHandle);
+}
+
+void ScriptLoaderRunnable::MaybeExecuteFinishedScripts(
+    ThreadSafeRequestHandle* aRequestHandle) {
+  AssertIsOnMainThread();
+
+  // We execute the last step if we don't have a pending operation with the
+  // cache and the loading is completed.
+  WorkerLoadContext* loadContext = aRequestHandle->GetContext();
+  if (!loadContext->IsAwaitingPromise()) {
+    if (aRequestHandle->GetContext()->IsTopLevel()) {
+      mWorkerRef->Private()->WorkerScriptLoaded();
+    }
+    DispatchProcessPendingRequests();
+  }
+}
+
+void ScriptLoaderRunnable::CancelMainThreadWithBindingAborted() {
+  AssertIsOnMainThread();
+  CancelMainThread(NS_BINDING_ABORTED);
+}
+
+void ScriptLoaderRunnable::CancelMainThread(nsresult aCancelResult) {
+  AssertIsOnMainThread();
+  if (IsCancelled()) {
+    return;
+  }
+
+  {
+    MutexAutoLock lock(mScriptLoader->CleanUpLock());
+
+    // Check if we have already cancelled, or if the worker has been killed
+    // before we cancel.
+    if (mScriptLoader->CleanedUp()) {
+      return;
+    }
+
+    mCancelMainThread = Some(aCancelResult);
+
+    for (ThreadSafeRequestHandle* handle : mLoadingRequests) {
+      if (handle->IsEmpty()) {
+        continue;
+      }
+
+      bool callLoadingFinished = true;
+
+      WorkerLoadContext* loadContext = handle->GetContext();
+      if (!loadContext) {
+        continue;
+      }
+
+      if (loadContext->IsAwaitingPromise()) {
+        MOZ_ASSERT(mWorkerRef->Private()->IsServiceWorker());
+        loadContext->mCachePromise->MaybeReject(NS_BINDING_ABORTED);
+        loadContext->mCachePromise = nullptr;
+        callLoadingFinished = false;
+      }
+      if (loadContext->mChannel) {
+        if (NS_SUCCEEDED(loadContext->mChannel->Cancel(aCancelResult))) {
+          callLoadingFinished = false;
+        } else {
+          NS_WARNING("Failed to cancel channel!");
+        }
+      }
+      if (callLoadingFinished && !loadContext->mLoadingFinished) {
+        LoadingFinished(handle, aCancelResult);
+      }
+    }
+    DispatchProcessPendingRequests();
+  }
+}
+
+void ScriptLoaderRunnable::DispatchProcessPendingRequests() {
+  AssertIsOnMainThread();
+
+  const auto begin = mLoadingRequests.begin();
+  const auto end = mLoadingRequests.end();
+  using Iterator = decltype(begin);
+  const auto maybeRangeToExecute =
+      [begin, end]() -> Maybe<std::pair<Iterator, Iterator>> {
+    // firstItToExecute is the first loadInfo where mExecutionScheduled is
+    // unset.
+    auto firstItToExecute = std::find_if(
+        begin, end, [](const RefPtr<ThreadSafeRequestHandle>& requestHandle) {
+          return !requestHandle->mExecutionScheduled;
+        });
+
+    if (firstItToExecute == end) {
+      return Nothing();
+    }
+
+    // firstItUnexecutable is the first loadInfo that is not yet finished.
+    // Update mExecutionScheduled on the ones we're about to schedule for
+    // execution.
+    const auto firstItUnexecutable =
+        std::find_if(firstItToExecute, end,
+                     [](RefPtr<ThreadSafeRequestHandle>& requestHandle) {
+                       MOZ_ASSERT(!requestHandle->IsEmpty());
+                       if (!requestHandle->Finished()) {
+                         return true;
+                       }
+
+                       // We can execute this one.
+                       requestHandle->mExecutionScheduled = true;
+
+                       return false;
+                     });
+
+    return firstItUnexecutable == firstItToExecute
+               ? Nothing()
+               : Some(std::pair(firstItToExecute, firstItUnexecutable));
+  }();
+
+  // If there are no unexecutable load infos, we can unuse things before the
+  // execution of the scripts and the stopping of the sync loop.
+  if (maybeRangeToExecute) {
+    if (maybeRangeToExecute->second == end) {
+      mCacheCreator = nullptr;
+    }
+
+    RefPtr<ScriptExecutorRunnable> runnable = new ScriptExecutorRunnable(
+        mScriptLoader, mWorkerRef->Private(), mScriptLoader->mSyncLoopTarget,
+        Span<RefPtr<ThreadSafeRequestHandle>>{maybeRangeToExecute->first,
+                                              maybeRangeToExecute->second});
+
+    if (!runnable->Dispatch() && mScriptLoader->mSyncLoopTarget) {
+      MOZ_ASSERT(false, "This should never fail!");
+    }
+  }
+}
+
+ScriptExecutorRunnable::ScriptExecutorRunnable(
+    WorkerScriptLoader* aScriptLoader, WorkerPrivate* aWorkerPrivate,
+    nsISerialEventTarget* aSyncLoopTarget,
+    Span<RefPtr<ThreadSafeRequestHandle>> aLoadedRequests)
+    : MainThreadWorkerSyncRunnable(aWorkerPrivate, aSyncLoopTarget),
+      mScriptLoader(aScriptLoader),
+      mLoadedRequests(aLoadedRequests) {}
+
+bool ScriptExecutorRunnable::IsDebuggerRunnable() const {
+  // ScriptExecutorRunnable is used to execute both worker and debugger scripts.
+  // In the latter case, the runnable needs to be dispatched to the debugger
+  // queue.
+  return mScriptLoader->IsDebuggerScript();
+}
+
+bool ScriptExecutorRunnable::PreRun(WorkerPrivate* aWorkerPrivate) {
+  aWorkerPrivate->AssertIsOnWorkerThread();
+
+  // We must be on the same worker as we started on.
+  MOZ_ASSERT(
+      mScriptLoader->mSyncLoopTarget == mSyncLoopTarget,
+      "Unexpected SyncLoopTarget. Check if the sync loop was closed early");
+
+  {
+    // There is a possibility that we cleaned up while this task was waiting to
+    // run. If this has happened, return and exit.
+    MutexAutoLock lock(mScriptLoader->CleanUpLock());
+    if (mScriptLoader->CleanedUp()) {
+      return true;
+    }
+
+    const auto& requestHandle = mLoadedRequests[0];
+    // Check if the request is still valid.
+    if (requestHandle->IsEmpty() ||
+        !requestHandle->GetContext()->IsTopLevel()) {
+      return true;
+    }
+  }
+
+  return mScriptLoader->StoreCSP();
+}
+
+bool ScriptExecutorRunnable::ProcessModuleScript(
+    JSContext* aCx, WorkerPrivate* aWorkerPrivate) {
+  // We should only ever have one script when processing modules
+  MOZ_ASSERT(mLoadedRequests.Length() == 1);
+  RefPtr<ScriptLoadRequest> request;
+  {
+    // There is a possibility that we cleaned up while this task was waiting to
+    // run. If this has happened, return and exit.
+    MutexAutoLock lock(mScriptLoader->CleanUpLock());
+    if (mScriptLoader->CleanedUp()) {
+      return true;
+    }
+
+    MOZ_ASSERT(mLoadedRequests.Length() == 1);
+    const auto& requestHandle = mLoadedRequests[0];
+    // The request must be valid.
+    MOZ_ASSERT(!requestHandle->IsEmpty());
+
+    // Release the request to the worker. From this point on, the Request Handle
+    // is empty.
+    request = requestHandle->ReleaseRequest();
+
+    // release lock. We will need it later if we cleanup.
+  }
+
+  MOZ_ASSERT(request->IsModuleRequest());
+
+  WorkerLoadContext* loadContext = request->GetWorkerLoadContext();
+  ModuleLoadRequest* moduleRequest = request->AsModuleRequest();
+
+  // DecreaseLoadingModuleRequestCount must be called before OnFetchComplete.
+  // OnFetchComplete will call ProcessPendingRequests, and in
+  // ProcessPendingRequests it will try to shutdown if
+  // AllModuleRequestsLoaded() returns true.
+  mScriptLoader->DecreaseLoadingModuleRequestCount();
+  moduleRequest->OnFetchComplete(loadContext->mLoadResult);
+
+  if (NS_FAILED(loadContext->mLoadResult)) {
+    if (moduleRequest->IsDynamicImport()) {
+      if (request->isInList()) {
+        moduleRequest->CancelDynamicImport(loadContext->mLoadResult);
+        mScriptLoader->TryShutdown();
+      }
+    } else if (!moduleRequest->IsTopLevel()) {
+      moduleRequest->Cancel();
+      mScriptLoader->TryShutdown();
+    } else {
+      moduleRequest->LoadFailed();
+    }
+  }
+  return true;
+}
+
+bool ScriptExecutorRunnable::ProcessClassicScripts(
+    JSContext* aCx, WorkerPrivate* aWorkerPrivate) {
+  // There is a possibility that we cleaned up while this task was waiting to
+  // run. If this has happened, return and exit.
+  {
+    MutexAutoLock lock(mScriptLoader->CleanUpLock());
+    if (mScriptLoader->CleanedUp()) {
+      return true;
+    }
+
+    for (const auto& requestHandle : mLoadedRequests) {
+      // The request must be valid.
+      MOZ_ASSERT(!requestHandle->IsEmpty());
+
+      // Release the request to the worker. From this point on, the Request
+      // Handle is empty.
+      RefPtr<ScriptLoadRequest> request = requestHandle->ReleaseRequest();
+      mScriptLoader->MaybeMoveToLoadedList(request);
+    }
+  }
+  return mScriptLoader->ProcessPendingRequests(aCx);
+}
+
+bool ScriptExecutorRunnable::WorkerRun(JSContext* aCx,
+                                       WorkerPrivate* aWorkerPrivate) {
+  aWorkerPrivate->AssertIsOnWorkerThread();
+
+  // We must be on the same worker as we started on.
+  MOZ_ASSERT(
+      mScriptLoader->mSyncLoopTarget == mSyncLoopTarget,
+      "Unexpected SyncLoopTarget. Check if the sync loop was closed early");
+
+  if (mLoadedRequests.begin()->get()->GetRequest()->IsModuleRequest()) {
+    return ProcessModuleScript(aCx, aWorkerPrivate);
+  }
+
+  return ProcessClassicScripts(aCx, aWorkerPrivate);
+}
+
+nsresult ScriptExecutorRunnable::Cancel() {
+  // We need to check first if cancel is called twice
+  nsresult rv = MainThreadWorkerSyncRunnable::Cancel();
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (mScriptLoader->AllScriptsExecuted() &&
+      mScriptLoader->AllModuleRequestsLoaded()) {
+    mScriptLoader->ShutdownScriptLoader(false, false);
+  }
+  return NS_OK;
+}
+
+} /* namespace loader */
+
+nsresult ChannelFromScriptURLMainThread(
+    nsIPrincipal* aPrincipal, Document* aParentDoc, nsILoadGroup* aLoadGroup,
+    nsIURI* aScriptURL, const WorkerType& aWorkerType,
+    const RequestCredentials& aCredentials,
+    const Maybe<ClientInfo>& aClientInfo,
+    nsContentPolicyType aMainScriptContentPolicyType,
+    nsICookieJarSettings* aCookieJarSettings, nsIReferrerInfo* aReferrerInfo,
+    nsIChannel** aChannel) {
+  AssertIsOnMainThread();
+
+  nsCOMPtr<nsIIOService> ios(do_GetIOService());
+
+  nsIScriptSecurityManager* secMan = nsContentUtils::GetSecurityManager();
+  NS_ASSERTION(secMan, "This should never be null!");
+
+  uint32_t secFlags;
+  nsresult rv;
+  if (aWorkerType == WorkerType::Module) {
+    rv = GetModuleSecFlags(true, aPrincipal, WorkerScript, aScriptURL,
+                           aCredentials, secFlags);
+  } else {
+    rv = GetClassicSecFlags(true, aScriptURL, aPrincipal, WorkerScript,
+                            secFlags);
+  }
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  return ChannelFromScriptURL(
+      aPrincipal, aParentDoc, nullptr, aLoadGroup, ios, secMan, aScriptURL,
+      aClientInfo, Maybe<ServiceWorkerDescriptor>(), true, WorkerScript,
+      aMainScriptContentPolicyType, nsIRequest::LOAD_NORMAL, secFlags,
+      aCookieJarSettings, aReferrerInfo, aChannel);
+}
+
+nsresult ChannelFromScriptURLWorkerThread(
+    JSContext* aCx, WorkerPrivate* aParent, const nsAString& aScriptURL,
+    const WorkerType& aWorkerType, const RequestCredentials& aCredentials,
+    WorkerLoadInfo& aLoadInfo) {
+  aParent->AssertIsOnWorkerThread();
+
+  RefPtr<ChannelGetterRunnable> getter = new ChannelGetterRunnable(
+      aParent, aScriptURL, aWorkerType, aCredentials, aLoadInfo);
+
+  ErrorResult rv;
+  getter->Dispatch(Canceling, rv);
+  if (rv.Failed()) {
+    NS_ERROR("Failed to dispatch!");
+    return rv.StealNSResult();
+  }
+
+  return getter->GetResult();
+}
+
+void ReportLoadError(ErrorResult& aRv, nsresult aLoadResult,
+                     const nsAString& aScriptURL) {
+  MOZ_ASSERT(!aRv.Failed());
+
+  nsPrintfCString err("Failed to load worker script at \"%s\"",
+                      NS_ConvertUTF16toUTF8(aScriptURL).get());
+
+  switch (aLoadResult) {
+    case NS_ERROR_FILE_NOT_FOUND:
+    case NS_ERROR_NOT_AVAILABLE:
+    case NS_ERROR_CORRUPTED_CONTENT:
+      aRv.Throw(NS_ERROR_DOM_NETWORK_ERR);
+      break;
+
+    case NS_ERROR_MALFORMED_URI:
+    case NS_ERROR_DOM_SYNTAX_ERR:
+      aRv.ThrowSyntaxError(err);
+      break;
+
+    case NS_BINDING_ABORTED:
+      // Note: we used to pretend like we didn't set an exception for
+      // NS_BINDING_ABORTED, but then ShutdownScriptLoader did it anyway.  The
+      // other callsite, in WorkerPrivate::Constructor, never passed in
+      // NS_BINDING_ABORTED.  So just throw it directly here.  Consumers will
+      // deal as needed.  But note that we do NOT want to use one of the
+      // Throw*Error() methods on ErrorResult for this case, because that will
+      // make it impossible for consumers to realize that our error was
+      // NS_BINDING_ABORTED.
+      aRv.Throw(aLoadResult);
+      return;
+
+    case NS_ERROR_DOM_BAD_URI:
+      // This is actually a security error.
+    case NS_ERROR_DOM_SECURITY_ERR:
+      aRv.ThrowSecurityError(err);
+      break;
+
+    default:
+      // For lack of anything better, go ahead and throw a NetworkError here.
+      // We don't want to throw a JS exception, because for toplevel script
+      // loads that would get squelched.
+      aRv.ThrowNetworkError(nsPrintfCString(
+          "Failed to load worker script at %s (nsresult = 0x%" PRIx32 ")",
+          NS_ConvertUTF16toUTF8(aScriptURL).get(),
+          static_cast<uint32_t>(aLoadResult)));
+      return;
+  }
+}
+
+void LoadMainScript(WorkerPrivate* aWorkerPrivate,
+                    UniquePtr<SerializedStackHolder> aOriginStack,
+                    const nsAString& aScriptURL,
+                    WorkerScriptType aWorkerScriptType, ErrorResult& aRv,
+                    const mozilla::Encoding* aDocumentEncoding) {
+  nsTArray<nsString> scriptURLs;
+
+  scriptURLs.AppendElement(aScriptURL);
+
+  LoadAllScripts(aWorkerPrivate, std::move(aOriginStack), scriptURLs, true,
+                 aWorkerScriptType, aRv, aDocumentEncoding);
+}
+
+void Load(WorkerPrivate* aWorkerPrivate,
+          UniquePtr<SerializedStackHolder> aOriginStack,
+          const nsTArray<nsString>& aScriptURLs,
+          WorkerScriptType aWorkerScriptType, ErrorResult& aRv) {
+  const uint32_t urlCount = aScriptURLs.Length();
+
+  if (!urlCount) {
+    return;
+  }
+
+  if (urlCount > MAX_CONCURRENT_SCRIPTS) {
+    aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
+    return;
+  }
+
+  LoadAllScripts(aWorkerPrivate, std::move(aOriginStack), aScriptURLs, false,
+                 aWorkerScriptType, aRv);
+}
+
+}  // namespace mozilla::dom::workerinternals