Adding upstream version 115.8.0esr.upstream/115.8.0esr

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

35 files changed, 1978 insertions, 0 deletions

diff --git a/dom/broadcastchannel/BroadcastChannel.cpp b/dom/broadcastchannel/BroadcastChannel.cpp
new file mode 100644
index 0000000000..9f1a461bb6
--- /dev/null
+++ b/dom/broadcastchannel/BroadcastChannel.cpp
@@ -0,0 +1,457 @@
+/* -*- 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 "BroadcastChannel.h"
+#include "BroadcastChannelChild.h"
+#include "mozilla/dom/BroadcastChannelBinding.h"
+#include "mozilla/dom/Navigator.h"
+#include "mozilla/dom/File.h"
+#include "mozilla/dom/MessageEvent.h"
+#include "mozilla/dom/MessageEventBinding.h"
+#include "mozilla/dom/StructuredCloneHolder.h"
+#include "mozilla/dom/ipc/StructuredCloneData.h"
+#include "mozilla/dom/RefMessageBodyService.h"
+#include "mozilla/dom/RootedDictionary.h"
+#include "mozilla/dom/SharedMessageBody.h"
+#include "mozilla/dom/WorkerScope.h"
+#include "mozilla/dom/WorkerRef.h"
+#include "mozilla/dom/WorkerRunnable.h"
+#include "mozilla/ipc/BackgroundChild.h"
+#include "mozilla/ipc/BackgroundUtils.h"
+#include "mozilla/ipc/PBackgroundChild.h"
+#include "mozilla/StorageAccess.h"
+
+#include "nsICookieJarSettings.h"
+#include "mozilla/dom/Document.h"
+
+#ifdef XP_WIN
+#  undef PostMessage
+#endif
+
+namespace mozilla {
+
+using namespace ipc;
+
+namespace dom {
+
+using namespace ipc;
+
+namespace {
+
+class CloseRunnable final : public DiscardableRunnable {
+ public:
+  explicit CloseRunnable(BroadcastChannel* aBC)
+      : DiscardableRunnable("BroadcastChannel CloseRunnable"), mBC(aBC) {
+    MOZ_ASSERT(mBC);
+  }
+
+  NS_IMETHOD Run() override {
+    mBC->Shutdown();
+    return NS_OK;
+  }
+
+ private:
+  ~CloseRunnable() = default;
+
+  RefPtr<BroadcastChannel> mBC;
+};
+
+class TeardownRunnable {
+ protected:
+  explicit TeardownRunnable(BroadcastChannelChild* aActor) : mActor(aActor) {
+    MOZ_ASSERT(mActor);
+  }
+
+  void RunInternal() {
+    MOZ_ASSERT(mActor);
+    if (!mActor->IsActorDestroyed()) {
+      mActor->SendClose();
+    }
+  }
+
+ protected:
+  virtual ~TeardownRunnable() = default;
+
+ private:
+  RefPtr<BroadcastChannelChild> mActor;
+};
+
+class TeardownRunnableOnMainThread final : public Runnable,
+                                           public TeardownRunnable {
+ public:
+  explicit TeardownRunnableOnMainThread(BroadcastChannelChild* aActor)
+      : Runnable("TeardownRunnableOnMainThread"), TeardownRunnable(aActor) {}
+
+  NS_IMETHOD Run() override {
+    RunInternal();
+    return NS_OK;
+  }
+};
+
+class TeardownRunnableOnWorker final : public WorkerControlRunnable,
+                                       public TeardownRunnable {
+ public:
+  TeardownRunnableOnWorker(WorkerPrivate* aWorkerPrivate,
+                           BroadcastChannelChild* aActor)
+      : WorkerControlRunnable(aWorkerPrivate, WorkerThreadUnchangedBusyCount),
+        TeardownRunnable(aActor) {}
+
+  bool WorkerRun(JSContext*, WorkerPrivate*) override {
+    RunInternal();
+    return true;
+  }
+
+  bool PreDispatch(WorkerPrivate* aWorkerPrivate) override { return true; }
+
+  void PostDispatch(WorkerPrivate* aWorkerPrivate,
+                    bool aDispatchResult) override {}
+
+  bool PreRun(WorkerPrivate* aWorkerPrivate) override { return true; }
+
+  void PostRun(JSContext* aCx, WorkerPrivate* aWorkerPrivate,
+               bool aRunResult) override {}
+};
+
+}  // namespace
+
+BroadcastChannel::BroadcastChannel(nsIGlobalObject* aGlobal,
+                                   const nsAString& aChannel,
+                                   const nsID& aPortUUID)
+    : DOMEventTargetHelper(aGlobal),
+      mRefMessageBodyService(RefMessageBodyService::GetOrCreate()),
+      mChannel(aChannel),
+      mState(StateActive),
+      mPortUUID(aPortUUID) {
+  MOZ_ASSERT(aGlobal);
+  KeepAliveIfHasListenersFor(nsGkAtoms::onmessage);
+}
+
+BroadcastChannel::~BroadcastChannel() {
+  Shutdown();
+  MOZ_ASSERT(!mWorkerRef);
+}
+
+JSObject* BroadcastChannel::WrapObject(JSContext* aCx,
+                                       JS::Handle<JSObject*> aGivenProto) {
+  return BroadcastChannel_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+/* static */
+already_AddRefed<BroadcastChannel> BroadcastChannel::Constructor(
+    const GlobalObject& aGlobal, const nsAString& aChannel, ErrorResult& aRv) {
+  nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(aGlobal.GetAsSupports());
+  if (NS_WARN_IF(!global)) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return nullptr;
+  }
+
+  nsID portUUID = {};
+  aRv = nsID::GenerateUUIDInPlace(portUUID);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  RefPtr<BroadcastChannel> bc =
+      new BroadcastChannel(global, aChannel, portUUID);
+
+  nsCOMPtr<nsIPrincipal> storagePrincipal;
+
+  StorageAccess storageAccess;
+
+  nsCOMPtr<nsICookieJarSettings> cjs;
+  if (NS_IsMainThread()) {
+    nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(global);
+    if (NS_WARN_IF(!window)) {
+      aRv.Throw(NS_ERROR_FAILURE);
+      return nullptr;
+    }
+
+    nsCOMPtr<nsIGlobalObject> incumbent = mozilla::dom::GetIncumbentGlobal();
+
+    if (!incumbent) {
+      aRv.Throw(NS_ERROR_FAILURE);
+      return nullptr;
+    }
+
+    nsCOMPtr<nsIScriptObjectPrincipal> sop = do_QueryInterface(incumbent);
+    if (NS_WARN_IF(!sop)) {
+      aRv.Throw(NS_ERROR_FAILURE);
+      return nullptr;
+    }
+
+    storagePrincipal = sop->GetEffectiveStoragePrincipal();
+    if (!storagePrincipal) {
+      aRv.Throw(NS_ERROR_UNEXPECTED);
+      return nullptr;
+    }
+    storageAccess = StorageAllowedForWindow(window);
+
+    Document* doc = window->GetExtantDoc();
+    if (doc) {
+      cjs = doc->CookieJarSettings();
+    }
+  } else {
+    JSContext* cx = aGlobal.Context();
+
+    WorkerPrivate* workerPrivate = GetWorkerPrivateFromContext(cx);
+    MOZ_ASSERT(workerPrivate);
+
+    RefPtr<StrongWorkerRef> workerRef = StrongWorkerRef::Create(
+        workerPrivate, "BroadcastChannel", [bc]() { bc->Shutdown(); });
+    // We are already shutting down the worker. Let's return a non-active
+    // object.
+    if (NS_WARN_IF(!workerRef)) {
+      aRv.Throw(NS_ERROR_FAILURE);
+      return nullptr;
+    }
+
+    storageAccess = workerPrivate->StorageAccess();
+
+    storagePrincipal = workerPrivate->GetEffectiveStoragePrincipal();
+
+    bc->mWorkerRef = workerRef;
+
+    cjs = workerPrivate->CookieJarSettings();
+  }
+
+  // We want to allow opaque origins.
+  if (!storagePrincipal->GetIsNullPrincipal() &&
+      (storageAccess == StorageAccess::eDeny ||
+       (ShouldPartitionStorage(storageAccess) &&
+        !StoragePartitioningEnabled(storageAccess, cjs)))) {
+    aRv.Throw(NS_ERROR_DOM_SECURITY_ERR);
+    return nullptr;
+  }
+
+  // Register this component to PBackground.
+  PBackgroundChild* actorChild = BackgroundChild::GetOrCreateForCurrentThread();
+  if (NS_WARN_IF(!actorChild)) {
+    // Firefox is probably shutting down. Let's return a 'generic' error.
+    aRv.Throw(NS_ERROR_FAILURE);
+    return nullptr;
+  }
+
+  nsAutoCString origin;
+  aRv = storagePrincipal->GetOrigin(origin);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+
+  nsString originForEvents;
+  aRv = nsContentUtils::GetUTFOrigin(storagePrincipal, originForEvents);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+
+  PrincipalInfo storagePrincipalInfo;
+  aRv = PrincipalToPrincipalInfo(storagePrincipal, &storagePrincipalInfo);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+
+  PBroadcastChannelChild* actor = actorChild->SendPBroadcastChannelConstructor(
+      storagePrincipalInfo, origin, nsString(aChannel));
+
+  bc->mActor = static_cast<BroadcastChannelChild*>(actor);
+  MOZ_ASSERT(bc->mActor);
+
+  bc->mActor->SetParent(bc);
+  bc->mOriginForEvents = std::move(originForEvents);
+
+  return bc.forget();
+}
+
+void BroadcastChannel::PostMessage(JSContext* aCx,
+                                   JS::Handle<JS::Value> aMessage,
+                                   ErrorResult& aRv) {
+  if (mState != StateActive) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+
+  Maybe<nsID> agentClusterId;
+  nsCOMPtr<nsIGlobalObject> global = GetOwnerGlobal();
+  MOZ_ASSERT(global);
+  if (global) {
+    agentClusterId = global->GetAgentClusterId();
+  }
+
+  RefPtr<SharedMessageBody> data = new SharedMessageBody(
+      StructuredCloneHolder::TransferringNotSupported, agentClusterId);
+
+  data->Write(aCx, aMessage, JS::UndefinedHandleValue, mPortUUID,
+              mRefMessageBodyService, aRv);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return;
+  }
+
+  RemoveDocFromBFCache();
+
+  MessageData message;
+  SharedMessageBody::FromSharedToMessageChild(mActor->Manager(), data, message);
+  mActor->SendPostMessage(message);
+}
+
+void BroadcastChannel::Close() {
+  if (mState != StateActive) {
+    return;
+  }
+
+  // We cannot call Shutdown() immediatelly because we could have some
+  // postMessage runnable already dispatched. Instead, we change the state to
+  // StateClosed and we shutdown the actor asynchrounsly.
+
+  mState = StateClosed;
+  RefPtr<CloseRunnable> runnable = new CloseRunnable(this);
+
+  if (NS_FAILED(NS_DispatchToCurrentThread(runnable))) {
+    NS_WARNING("Failed to dispatch to the current thread!");
+  }
+}
+
+void BroadcastChannel::Shutdown() {
+  mState = StateClosed;
+
+  // The DTOR of this WorkerRef will release the worker for us.
+  mWorkerRef = nullptr;
+
+  if (mActor) {
+    mActor->SetParent(nullptr);
+
+    if (NS_IsMainThread()) {
+      RefPtr<TeardownRunnableOnMainThread> runnable =
+          new TeardownRunnableOnMainThread(mActor);
+      NS_DispatchToCurrentThread(runnable);
+    } else {
+      WorkerPrivate* workerPrivate = GetCurrentThreadWorkerPrivate();
+      MOZ_ASSERT(workerPrivate);
+
+      RefPtr<TeardownRunnableOnWorker> runnable =
+          new TeardownRunnableOnWorker(workerPrivate, mActor);
+      runnable->Dispatch();
+    }
+
+    mActor = nullptr;
+  }
+
+  IgnoreKeepAliveIfHasListenersFor(nsGkAtoms::onmessage);
+}
+
+void BroadcastChannel::RemoveDocFromBFCache() {
+  if (!NS_IsMainThread()) {
+    return;
+  }
+
+  if (nsPIDOMWindowInner* window = GetOwner()) {
+    window->RemoveFromBFCacheSync();
+  }
+}
+
+void BroadcastChannel::DisconnectFromOwner() {
+  Shutdown();
+  DOMEventTargetHelper::DisconnectFromOwner();
+}
+
+void BroadcastChannel::MessageReceived(const MessageData& aData) {
+  if (NS_FAILED(CheckCurrentGlobalCorrectness())) {
+    RemoveDocFromBFCache();
+    return;
+  }
+
+  // Let's ignore messages after a close/shutdown.
+  if (mState != StateActive) {
+    return;
+  }
+
+  nsCOMPtr<nsIGlobalObject> globalObject;
+
+  if (NS_IsMainThread()) {
+    globalObject = GetParentObject();
+  } else {
+    WorkerPrivate* workerPrivate = GetCurrentThreadWorkerPrivate();
+    MOZ_ASSERT(workerPrivate);
+    globalObject = workerPrivate->GlobalScope();
+  }
+
+  AutoJSAPI jsapi;
+  if (!globalObject || !jsapi.Init(globalObject)) {
+    NS_WARNING("Failed to initialize AutoJSAPI object.");
+    return;
+  }
+
+  JSContext* cx = jsapi.cx();
+
+  RefPtr<SharedMessageBody> data = SharedMessageBody::FromMessageToSharedChild(
+      aData, StructuredCloneHolder::TransferringNotSupported);
+  if (NS_WARN_IF(!data)) {
+    DispatchError(cx);
+    return;
+  }
+
+  IgnoredErrorResult rv;
+  JS::Rooted<JS::Value> value(cx);
+
+  data->Read(cx, &value, mRefMessageBodyService,
+             SharedMessageBody::ReadMethod::KeepRefMessageBody, rv);
+  if (NS_WARN_IF(rv.Failed())) {
+    JS_ClearPendingException(cx);
+    DispatchError(cx);
+    return;
+  }
+
+  RemoveDocFromBFCache();
+
+  RootedDictionary<MessageEventInit> init(cx);
+  init.mBubbles = false;
+  init.mCancelable = false;
+  init.mOrigin = mOriginForEvents;
+  init.mData = value;
+
+  RefPtr<MessageEvent> event =
+      MessageEvent::Constructor(this, u"message"_ns, init);
+
+  event->SetTrusted(true);
+
+  DispatchEvent(*event);
+}
+
+void BroadcastChannel::MessageDelivered(const nsID& aMessageID,
+                                        uint32_t aOtherBCs) {
+  mRefMessageBodyService->SetMaxCount(aMessageID, aOtherBCs);
+}
+
+void BroadcastChannel::DispatchError(JSContext* aCx) {
+  RootedDictionary<MessageEventInit> init(aCx);
+  init.mBubbles = false;
+  init.mCancelable = false;
+  init.mOrigin = mOriginForEvents;
+
+  RefPtr<Event> event =
+      MessageEvent::Constructor(this, u"messageerror"_ns, init);
+  event->SetTrusted(true);
+
+  DispatchEvent(*event);
+}
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(BroadcastChannel)
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(BroadcastChannel,
+                                                  DOMEventTargetHelper)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(BroadcastChannel,
+                                                DOMEventTargetHelper)
+  tmp->Shutdown();
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(BroadcastChannel)
+NS_INTERFACE_MAP_END_INHERITING(DOMEventTargetHelper)
+
+NS_IMPL_ADDREF_INHERITED(BroadcastChannel, DOMEventTargetHelper)
+NS_IMPL_RELEASE_INHERITED(BroadcastChannel, DOMEventTargetHelper)
+
+}  // namespace dom
+}  // namespace mozilla
diff --git a/dom/broadcastchannel/BroadcastChannel.h b/dom/broadcastchannel/BroadcastChannel.h
new file mode 100644
index 0000000000..280913e8f8
--- /dev/null
+++ b/dom/broadcastchannel/BroadcastChannel.h
@@ -0,0 +1,93 @@
+/* -*- 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/. */
+
+#ifndef mozilla_dom_BroadcastChannel_h
+#define mozilla_dom_BroadcastChannel_h
+
+#include "mozilla/Attributes.h"
+#include "mozilla/DOMEventTargetHelper.h"
+#include "nsTArray.h"
+#include "mozilla/RefPtr.h"
+
+class nsIGlobalObject;
+
+namespace mozilla {
+
+namespace ipc {
+class PrincipalInfo;
+}  // namespace ipc
+
+namespace dom {
+
+class BroadcastChannelChild;
+class RefMessageBodyService;
+class WorkerRef;
+
+class BroadcastChannel final : public DOMEventTargetHelper {
+  friend class BroadcastChannelChild;
+
+  using PrincipalInfo = mozilla::ipc::PrincipalInfo;
+
+ public:
+  NS_DECL_ISUPPORTS_INHERITED
+
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(BroadcastChannel,
+                                           DOMEventTargetHelper)
+
+  virtual JSObject* WrapObject(JSContext* aCx,
+                               JS::Handle<JSObject*> aGivenProto) override;
+
+  static already_AddRefed<BroadcastChannel> Constructor(
+      const GlobalObject& aGlobal, const nsAString& aChannel, ErrorResult& aRv);
+
+  void GetName(nsAString& aName) const { aName = mChannel; }
+
+  void PostMessage(JSContext* aCx, JS::Handle<JS::Value> aMessage,
+                   ErrorResult& aRv);
+
+  void Close();
+
+  IMPL_EVENT_HANDLER(message)
+  IMPL_EVENT_HANDLER(messageerror)
+
+  void Shutdown();
+
+ private:
+  BroadcastChannel(nsIGlobalObject* aGlobal, const nsAString& aChannel,
+                   const nsID& aPortUUID);
+
+  ~BroadcastChannel();
+
+  void MessageReceived(const MessageData& aData);
+
+  void MessageDelivered(const nsID& aMessageID, uint32_t aOtherBCs);
+
+  void RemoveDocFromBFCache();
+
+  void DisconnectFromOwner() override;
+
+  void DispatchError(JSContext* aCx);
+
+  RefPtr<BroadcastChannelChild> mActor;
+
+  RefPtr<RefMessageBodyService> mRefMessageBodyService;
+
+  RefPtr<WorkerRef> mWorkerRef;
+
+  nsString mChannel;
+  nsString mOriginForEvents;
+
+  enum { StateActive, StateClosed } mState;
+
+  // This ID is used to identify the messages-by-reference sent by this port.
+  // See RefMessageBodyService.
+  nsID mPortUUID;
+};
+
+}  // namespace dom
+}  // namespace mozilla
+
+#endif  // mozilla_dom_BroadcastChannel_h
diff --git a/dom/broadcastchannel/BroadcastChannelChild.cpp b/dom/broadcastchannel/BroadcastChannelChild.cpp
new file mode 100644
index 0000000000..30e2633c5d
--- /dev/null
+++ b/dom/broadcastchannel/BroadcastChannelChild.cpp
@@ -0,0 +1,48 @@
+/* -*- 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 "BroadcastChannelChild.h"
+#include "BroadcastChannel.h"
+
+namespace mozilla {
+
+using namespace ipc;
+
+namespace dom {
+
+BroadcastChannelChild::BroadcastChannelChild()
+    : mBC(nullptr), mActorDestroyed(false) {}
+
+BroadcastChannelChild::~BroadcastChannelChild() { MOZ_ASSERT(!mBC); }
+
+mozilla::ipc::IPCResult BroadcastChannelChild::RecvNotify(
+    const MessageData& aData) {
+  if (!mBC) {
+    // The object is going to be deleted soon. No notify is required.
+    return IPC_OK();
+  }
+
+  mBC->MessageReceived(aData);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult BroadcastChannelChild::RecvRefMessageDelivered(
+    const nsID& aMessageID, const uint32_t& aOtherBCs) {
+  if (!mBC) {
+    // The object is going to be deleted soon. No notify is required.
+    return IPC_OK();
+  }
+
+  mBC->MessageDelivered(aMessageID, aOtherBCs);
+  return IPC_OK();
+}
+
+void BroadcastChannelChild::ActorDestroy(ActorDestroyReason aWhy) {
+  mActorDestroyed = true;
+}
+
+}  // namespace dom
+}  // namespace mozilla
diff --git a/dom/broadcastchannel/BroadcastChannelChild.h b/dom/broadcastchannel/BroadcastChannelChild.h
new file mode 100644
index 0000000000..5c5cae4fd7
--- /dev/null
+++ b/dom/broadcastchannel/BroadcastChannelChild.h
@@ -0,0 +1,53 @@
+/* -*- 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/. */
+
+#ifndef mozilla_dom_BroadcastChannelChild_h
+#define mozilla_dom_BroadcastChannelChild_h
+
+#include "mozilla/dom/PBroadcastChannelChild.h"
+
+namespace mozilla {
+
+namespace ipc {
+class BackgroundChildImpl;
+}  // namespace ipc
+
+namespace dom {
+
+class BroadcastChannel;
+
+class BroadcastChannelChild final : public PBroadcastChannelChild {
+  friend class mozilla::ipc::BackgroundChildImpl;
+
+ public:
+  NS_INLINE_DECL_REFCOUNTING(BroadcastChannelChild)
+
+  void SetParent(BroadcastChannel* aBC) { mBC = aBC; }
+
+  virtual mozilla::ipc::IPCResult RecvNotify(const MessageData& aData) override;
+
+  virtual mozilla::ipc::IPCResult RecvRefMessageDelivered(
+      const nsID& aMessageID, const uint32_t& aOtherBCs) override;
+
+  bool IsActorDestroyed() const { return mActorDestroyed; }
+
+ private:
+  BroadcastChannelChild();
+  ~BroadcastChannelChild();
+
+  virtual void ActorDestroy(ActorDestroyReason aWhy) override;
+
+  // This raw pointer is actually the parent object.
+  // It's set to null when the parent object is deleted.
+  BroadcastChannel* mBC;
+
+  bool mActorDestroyed;
+};
+
+}  // namespace dom
+}  // namespace mozilla
+
+#endif  // mozilla_dom_BroadcastChannelChild_h
diff --git a/dom/broadcastchannel/BroadcastChannelParent.cpp b/dom/broadcastchannel/BroadcastChannelParent.cpp
new file mode 100644
index 0000000000..56c528c933
--- /dev/null
+++ b/dom/broadcastchannel/BroadcastChannelParent.cpp
@@ -0,0 +1,71 @@
+/* -*- 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 "BroadcastChannelParent.h"
+#include "BroadcastChannelService.h"
+#include "mozilla/dom/File.h"
+#include "mozilla/dom/IPCBlobUtils.h"
+#include "mozilla/ipc/BackgroundParent.h"
+#include "mozilla/ipc/IPCStreamUtils.h"
+#include "mozilla/Unused.h"
+
+namespace mozilla {
+
+using namespace ipc;
+
+namespace dom {
+
+BroadcastChannelParent::BroadcastChannelParent(
+    const nsAString& aOriginChannelKey)
+    : mService(BroadcastChannelService::GetOrCreate()),
+      mOriginChannelKey(aOriginChannelKey) {
+  AssertIsOnBackgroundThread();
+  mService->RegisterActor(this, mOriginChannelKey);
+}
+
+BroadcastChannelParent::~BroadcastChannelParent() {
+  AssertIsOnBackgroundThread();
+}
+
+mozilla::ipc::IPCResult BroadcastChannelParent::RecvPostMessage(
+    const MessageData& aData) {
+  AssertIsOnBackgroundThread();
+
+  if (NS_WARN_IF(!mService)) {
+    return IPC_FAIL_NO_REASON(this);
+  }
+
+  mService->PostMessage(this, aData, mOriginChannelKey);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult BroadcastChannelParent::RecvClose() {
+  AssertIsOnBackgroundThread();
+
+  if (NS_WARN_IF(!mService)) {
+    return IPC_FAIL_NO_REASON(this);
+  }
+
+  mService->UnregisterActor(this, mOriginChannelKey);
+  mService = nullptr;
+
+  Unused << Send__delete__(this);
+
+  return IPC_OK();
+}
+
+void BroadcastChannelParent::ActorDestroy(ActorDestroyReason aWhy) {
+  AssertIsOnBackgroundThread();
+
+  if (mService) {
+    // This object is about to be released and with it, also mService will be
+    // released too.
+    mService->UnregisterActor(this, mOriginChannelKey);
+  }
+}
+
+}  // namespace dom
+}  // namespace mozilla
diff --git a/dom/broadcastchannel/BroadcastChannelParent.h b/dom/broadcastchannel/BroadcastChannelParent.h
new file mode 100644
index 0000000000..fdca75d213
--- /dev/null
+++ b/dom/broadcastchannel/BroadcastChannelParent.h
@@ -0,0 +1,46 @@
+/* -*- 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/. */
+
+#ifndef mozilla_dom_BroadcastChannelParent_h
+#define mozilla_dom_BroadcastChannelParent_h
+
+#include "mozilla/dom/PBroadcastChannelParent.h"
+
+namespace mozilla {
+
+namespace ipc {
+class BackgroundParentImpl;
+class PrincipalInfo;
+}  // namespace ipc
+
+namespace dom {
+
+class BroadcastChannelService;
+
+class BroadcastChannelParent final : public PBroadcastChannelParent {
+  friend class mozilla::ipc::BackgroundParentImpl;
+
+  using PrincipalInfo = mozilla::ipc::PrincipalInfo;
+
+ private:
+  explicit BroadcastChannelParent(const nsAString& aOriginChannelKey);
+  ~BroadcastChannelParent();
+
+  virtual mozilla::ipc::IPCResult RecvPostMessage(
+      const MessageData& aData) override;
+
+  virtual mozilla::ipc::IPCResult RecvClose() override;
+
+  virtual void ActorDestroy(ActorDestroyReason aWhy) override;
+
+  RefPtr<BroadcastChannelService> mService;
+  const nsString mOriginChannelKey;
+};
+
+}  // namespace dom
+}  // namespace mozilla
+
+#endif  // mozilla_dom_BroadcastChannelParent_h
diff --git a/dom/broadcastchannel/BroadcastChannelService.cpp b/dom/broadcastchannel/BroadcastChannelService.cpp
new file mode 100644
index 0000000000..c3dab2b28a
--- /dev/null
+++ b/dom/broadcastchannel/BroadcastChannelService.cpp
@@ -0,0 +1,178 @@
+/* -*- 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 "BroadcastChannelService.h"
+#include "BroadcastChannelParent.h"
+#include "mozilla/dom/BlobImpl.h"
+#include "mozilla/dom/File.h"
+#include "mozilla/dom/IPCBlobUtils.h"
+#include "mozilla/ipc/BackgroundParent.h"
+
+#ifdef XP_WIN
+#  undef PostMessage
+#endif
+
+namespace mozilla {
+
+using namespace ipc;
+
+namespace dom {
+
+namespace {
+
+BroadcastChannelService* sInstance = nullptr;
+
+ClonedMessageData CloneClonedMessageData(const ClonedMessageData& aOther) {
+  auto cloneData = SerializedStructuredCloneBuffer{};
+  cloneData.data.initScope(aOther.data().data.scope());
+  const bool res = cloneData.data.Append(aOther.data().data);
+  MOZ_RELEASE_ASSERT(res, "out of memory");
+  return {std::move(cloneData), aOther.blobs(), aOther.inputStreams(),
+          aOther.identifiers()};
+}
+
+MessageData CloneMessageData(const MessageData& aOther) {
+  switch (aOther.data().type()) {
+    case MessageDataType::TClonedMessageData:
+      return {aOther.agentClusterId(),
+              CloneClonedMessageData(aOther.data().get_ClonedMessageData())};
+    case MessageDataType::TRefMessageData:
+      return {aOther.agentClusterId(), aOther.data().get_RefMessageData()};
+    default:
+      MOZ_CRASH("Unexpected MessageDataType type");
+  }
+}
+
+}  // namespace
+
+BroadcastChannelService::BroadcastChannelService() {
+  AssertIsOnBackgroundThread();
+
+  // sInstance is a raw BroadcastChannelService*.
+  MOZ_ASSERT(!sInstance);
+  sInstance = this;
+}
+
+BroadcastChannelService::~BroadcastChannelService() {
+  AssertIsOnBackgroundThread();
+  MOZ_ASSERT(sInstance == this);
+  MOZ_ASSERT(mAgents.Count() == 0);
+
+  sInstance = nullptr;
+}
+
+// static
+already_AddRefed<BroadcastChannelService>
+BroadcastChannelService::GetOrCreate() {
+  AssertIsOnBackgroundThread();
+
+  RefPtr<BroadcastChannelService> instance = sInstance;
+  if (!instance) {
+    instance = new BroadcastChannelService();
+  }
+  return instance.forget();
+}
+
+void BroadcastChannelService::RegisterActor(
+    BroadcastChannelParent* aParent, const nsAString& aOriginChannelKey) {
+  AssertIsOnBackgroundThread();
+  MOZ_ASSERT(aParent);
+
+  auto* const parents = mAgents.GetOrInsertNew(aOriginChannelKey);
+
+  MOZ_ASSERT(!parents->Contains(aParent));
+  parents->AppendElement(aParent);
+}
+
+void BroadcastChannelService::UnregisterActor(
+    BroadcastChannelParent* aParent, const nsAString& aOriginChannelKey) {
+  AssertIsOnBackgroundThread();
+  MOZ_ASSERT(aParent);
+
+  if (auto entry = mAgents.Lookup(aOriginChannelKey)) {
+    entry.Data()->RemoveElement(aParent);
+    // remove the entry if the array is now empty
+    if (entry.Data()->IsEmpty()) {
+      entry.Remove();
+    }
+  } else {
+    MOZ_CRASH("Invalid state");
+  }
+}
+
+void BroadcastChannelService::PostMessage(BroadcastChannelParent* aParent,
+                                          const MessageData& aData,
+                                          const nsAString& aOriginChannelKey) {
+  AssertIsOnBackgroundThread();
+  MOZ_ASSERT(aParent);
+
+  nsTArray<BroadcastChannelParent*>* parents;
+  if (!mAgents.Get(aOriginChannelKey, &parents)) {
+    MOZ_CRASH("Invalid state");
+  }
+
+  // We need to keep the array alive for the life-time of this operation.
+  nsTArray<RefPtr<BlobImpl>> blobImpls;
+  if (aData.data().type() == MessageDataType::TClonedMessageData) {
+    const nsTArray<IPCBlob>& blobs =
+        aData.data().get_ClonedMessageData().blobs();
+    if (!blobs.IsEmpty()) {
+      blobImpls.SetCapacity(blobs.Length());
+
+      for (uint32_t i = 0, len = blobs.Length(); i < len; ++i) {
+        RefPtr<BlobImpl> impl = IPCBlobUtils::Deserialize(blobs[i]);
+
+        MOZ_ASSERT(impl);
+        blobImpls.AppendElement(impl);
+      }
+    }
+  }
+
+  uint32_t selectedActorsOnSamePid = 0;
+
+  // For each parent actor, we notify the message.
+  for (uint32_t i = 0; i < parents->Length(); ++i) {
+    BroadcastChannelParent* parent = parents->ElementAt(i);
+    MOZ_ASSERT(parent);
+
+    if (parent == aParent) {
+      continue;
+    }
+
+    if (parent->OtherPid() == aParent->OtherPid()) {
+      ++selectedActorsOnSamePid;
+    }
+
+    // We need to have a copy of the data for this parent.
+    MessageData newData = CloneMessageData(aData);
+    MOZ_ASSERT(newData.data().type() == aData.data().type());
+
+    if (!blobImpls.IsEmpty()) {
+      nsTArray<IPCBlob>& newBlobImpls =
+          newData.data().get_ClonedMessageData().blobs();
+      MOZ_ASSERT(blobImpls.Length() == newBlobImpls.Length());
+
+      // Serialize Blob objects for this message.
+      for (uint32_t i = 0, len = blobImpls.Length(); i < len; ++i) {
+        nsresult rv = IPCBlobUtils::Serialize(blobImpls[i], newBlobImpls[i]);
+        if (NS_WARN_IF(NS_FAILED(rv))) {
+          return;
+        }
+      }
+    }
+
+    Unused << parent->SendNotify(newData);
+  }
+
+  // If this is a refMessageData, we need to know when it can be released.
+  if (aData.data().type() == MessageDataType::TRefMessageData) {
+    Unused << aParent->SendRefMessageDelivered(
+        aData.data().get_RefMessageData().uuid(), selectedActorsOnSamePid);
+  }
+}
+
+}  // namespace dom
+}  // namespace mozilla
diff --git a/dom/broadcastchannel/BroadcastChannelService.h b/dom/broadcastchannel/BroadcastChannelService.h
new file mode 100644
index 0000000000..5ec525d799
--- /dev/null
+++ b/dom/broadcastchannel/BroadcastChannelService.h
@@ -0,0 +1,47 @@
+/* -*- 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/. */
+
+#ifndef mozilla_dom_BroadcastChannelService_h
+#define mozilla_dom_BroadcastChannelService_h
+
+#include "nsISupportsImpl.h"
+#include "nsHashKeys.h"
+#include "nsClassHashtable.h"
+
+#ifdef XP_WIN
+#  undef PostMessage
+#endif
+
+namespace mozilla::dom {
+
+class BroadcastChannelParent;
+class MessageData;
+
+class BroadcastChannelService final {
+ public:
+  NS_INLINE_DECL_REFCOUNTING(BroadcastChannelService)
+
+  static already_AddRefed<BroadcastChannelService> GetOrCreate();
+
+  void RegisterActor(BroadcastChannelParent* aParent,
+                     const nsAString& aOriginChannelKey);
+  void UnregisterActor(BroadcastChannelParent* aParent,
+                       const nsAString& aOriginChannelKey);
+
+  void PostMessage(BroadcastChannelParent* aParent, const MessageData& aData,
+                   const nsAString& aOriginChannelKey);
+
+ private:
+  BroadcastChannelService();
+  ~BroadcastChannelService();
+
+  // Raw Pointers because the actors keep alive this service.
+  nsClassHashtable<nsStringHashKey, nsTArray<BroadcastChannelParent*>> mAgents;
+};
+
+}  // namespace mozilla::dom
+
+#endif  // mozilla_dom_BroadcastChannelService_h
diff --git a/dom/broadcastchannel/PBroadcastChannel.ipdl b/dom/broadcastchannel/PBroadcastChannel.ipdl
new file mode 100644
index 0000000000..6ff27b45d8
--- /dev/null
+++ b/dom/broadcastchannel/PBroadcastChannel.ipdl
@@ -0,0 +1,36 @@
+/* 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 protocol PBackground;
+
+include DOMTypes;
+
+using struct nsID from "nsID.h";
+
+namespace mozilla {
+namespace dom {
+
+// This protocol is used for the BroadcastChannel API
+[ManualDealloc, ChildImpl=virtual, ParentImpl=virtual]
+protocol PBroadcastChannel
+{
+  manager PBackground;
+
+parent:
+  async PostMessage(MessageData message);
+  async Close();
+
+child:
+  // A message must be delivered.
+  async Notify(MessageData message);
+
+  // A message has been delivered to other channels. It can be removed after
+  // all the actorsOnSamePid have retrieved it.
+  async RefMessageDelivered(nsID messageID, uint32_t actorsOnSamePid);
+
+  async __delete__();
+};
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/broadcastchannel/moz.build b/dom/broadcastchannel/moz.build
new file mode 100644
index 0000000000..a36176af8a
--- /dev/null
+++ b/dom/broadcastchannel/moz.build
@@ -0,0 +1,30 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# 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/.
+
+with Files("**"):
+    BUG_COMPONENT = ("Core", "DOM: postMessage")
+
+EXPORTS.mozilla.dom += [
+    "BroadcastChannel.h",
+]
+
+UNIFIED_SOURCES += [
+    "BroadcastChannel.cpp",
+    "BroadcastChannelChild.cpp",
+    "BroadcastChannelParent.cpp",
+    "BroadcastChannelService.cpp",
+]
+
+IPDL_SOURCES += [
+    "PBroadcastChannel.ipdl",
+]
+
+MOCHITEST_MANIFESTS += ["tests/mochitest.ini"]
+BROWSER_CHROME_MANIFESTS += ["tests/browser.ini"]
+
+include("/ipc/chromium/chromium-config.mozbuild")
+
+FINAL_LIBRARY = "xul"
diff --git a/dom/broadcastchannel/tests/blank.html b/dom/broadcastchannel/tests/blank.html
new file mode 100644
index 0000000000..358db717dd
--- /dev/null
+++ b/dom/broadcastchannel/tests/blank.html
@@ -0,0 +1,2 @@
+<!DOCTYPE HTML>
+<html><body></body></html>
diff --git a/dom/broadcastchannel/tests/broadcastchannel_sharedWorker.js b/dom/broadcastchannel/tests/broadcastchannel_sharedWorker.js
new file mode 100644
index 0000000000..17fb806371
--- /dev/null
+++ b/dom/broadcastchannel/tests/broadcastchannel_sharedWorker.js
@@ -0,0 +1,17 @@
+/* eslint-env worker */
+
+onconnect = function (evt) {
+  evt.ports[0].onmessage = function (evt1) {
+    var bc = new BroadcastChannel("foobar");
+    bc.addEventListener("message", function (event) {
+      bc.postMessage(
+        event.data == "hello world from the window"
+          ? "hello world from the worker"
+          : "KO"
+      );
+      bc.close();
+    });
+
+    evt1.target.postMessage("READY");
+  };
+};
diff --git a/dom/broadcastchannel/tests/broadcastchannel_worker_alive.js b/dom/broadcastchannel/tests/broadcastchannel_worker_alive.js
new file mode 100644
index 0000000000..da608c6d20
--- /dev/null
+++ b/dom/broadcastchannel/tests/broadcastchannel_worker_alive.js
@@ -0,0 +1,7 @@
+new BroadcastChannel("foobar").addEventListener("message", function (event) {
+  if (event.data != "READY") {
+    event.target.postMessage(event.data);
+  }
+});
+
+new BroadcastChannel("foobar").postMessage("READY");
diff --git a/dom/broadcastchannel/tests/browser.ini b/dom/broadcastchannel/tests/browser.ini
new file mode 100644
index 0000000000..b036a1e9bf
--- /dev/null
+++ b/dom/broadcastchannel/tests/browser.ini
@@ -0,0 +1,6 @@
+[DEFAULT]
+skip-if = os == 'android'
+support-files =
+  blank.html
+
+[browser_private_browsing.js]
diff --git a/dom/broadcastchannel/tests/browser_private_browsing.js b/dom/broadcastchannel/tests/browser_private_browsing.js
new file mode 100644
index 0000000000..e61e8ae58e
--- /dev/null
+++ b/dom/broadcastchannel/tests/browser_private_browsing.js
@@ -0,0 +1,93 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+const URL =
+  "http://mochi.test:8888/browser/dom/broadcastchannel/tests/blank.html";
+
+add_task(async function () {
+  var win1 = OpenBrowserWindow({ private: true });
+  var win1Promise = new win1.Promise(resolve => {
+    win1.addEventListener(
+      "load",
+      function () {
+        resolve();
+      },
+      { once: true }
+    );
+  });
+  await win1Promise;
+
+  var win2 = OpenBrowserWindow({ private: false });
+  var win2Promise = new win2.Promise(resolve => {
+    win2.addEventListener(
+      "load",
+      function () {
+        resolve();
+      },
+      { once: true }
+    );
+  });
+  await win2Promise;
+
+  var tab1 = BrowserTestUtils.addTab(win1.gBrowser, URL);
+  await BrowserTestUtils.browserLoaded(win1.gBrowser.getBrowserForTab(tab1));
+  var browser1 = gBrowser.getBrowserForTab(tab1);
+
+  var tab2 = BrowserTestUtils.addTab(win2.gBrowser, URL);
+  await BrowserTestUtils.browserLoaded(win2.gBrowser.getBrowserForTab(tab2));
+  var browser2 = gBrowser.getBrowserForTab(tab2);
+
+  var p1 = SpecialPowers.spawn(browser1, [], function (opts) {
+    return new content.window.Promise(resolve => {
+      content.window.bc = new content.window.BroadcastChannel("foobar");
+      content.window.bc.onmessage = function (e) {
+        resolve(e.data);
+      };
+    });
+  });
+
+  var p2 = SpecialPowers.spawn(browser2, [], function (opts) {
+    return new content.window.Promise(resolve => {
+      content.window.bc = new content.window.BroadcastChannel("foobar");
+      content.window.bc.onmessage = function (e) {
+        resolve(e.data);
+      };
+    });
+  });
+
+  await SpecialPowers.spawn(browser1, [], function (opts) {
+    return new content.window.Promise(resolve => {
+      var bc = new content.window.BroadcastChannel("foobar");
+      bc.postMessage("hello world from private browsing");
+      resolve();
+    });
+  });
+
+  await SpecialPowers.spawn(browser2, [], function (opts) {
+    return new content.window.Promise(resolve => {
+      var bc = new content.window.BroadcastChannel("foobar");
+      bc.postMessage("hello world from non private browsing");
+      resolve();
+    });
+  });
+
+  var what1 = await p1;
+  is(
+    what1,
+    "hello world from private browsing",
+    "No messages received from the other window."
+  );
+
+  var what2 = await p2;
+  is(
+    what2,
+    "hello world from non private browsing",
+    "No messages received from the other window."
+  );
+
+  BrowserTestUtils.removeTab(tab1);
+  await BrowserTestUtils.closeWindow(win1);
+
+  BrowserTestUtils.removeTab(tab2);
+  await BrowserTestUtils.closeWindow(win2);
+});
diff --git a/dom/broadcastchannel/tests/file_mozbrowser.html b/dom/broadcastchannel/tests/file_mozbrowser.html
new file mode 100644
index 0000000000..6370500d98
--- /dev/null
+++ b/dom/broadcastchannel/tests/file_mozbrowser.html
@@ -0,0 +1,20 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>MozBrowser iframe</title>
+</head>
+<body>
+<div id="container"></div>
+  <script type="application/javascript">
+
+  var ifr = document.createElement("iframe");
+  ifr.src = "http://mochi.test:8888/tests/dom/broadcastchannel/tests/iframe_mozbrowser.html";
+  ifr.onload = function() { alert("DONE"); };
+
+  var domParent = document.getElementById("container");
+  domParent.appendChild(ifr);
+
+  </script>
+</body>
+</html>
diff --git a/dom/broadcastchannel/tests/file_mozbrowser2.html b/dom/broadcastchannel/tests/file_mozbrowser2.html
new file mode 100644
index 0000000000..2e5f394eb8
--- /dev/null
+++ b/dom/broadcastchannel/tests/file_mozbrowser2.html
@@ -0,0 +1,21 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>MozBrowser iframe</title>
+</head>
+<body>
+<div id="container"></div>
+  <script type="application/javascript">
+
+  var ifr = document.createElement("iframe");
+  ifr.setAttribute("mozbrowser", true);
+  ifr.src = "http://mochi.test:8888/tests/dom/broadcastchannel/tests/iframe_mozbrowser2.html";
+  ifr.onload = function() { alert("DONE"); };
+
+  var domParent = document.getElementById("container");
+  domParent.appendChild(ifr);
+
+  </script>
+</body>
+</html>
diff --git a/dom/broadcastchannel/tests/iframe_broadcastchannel.html b/dom/broadcastchannel/tests/iframe_broadcastchannel.html
new file mode 100644
index 0000000000..2d1724da0b
--- /dev/null
+++ b/dom/broadcastchannel/tests/iframe_broadcastchannel.html
@@ -0,0 +1,33 @@
+<!DOCTYPE HTML>
+<html>
+<body>
+  <script type="application/javascript">
+
+function is(a, b, msg) {
+  ok(a == b, msg);
+}
+
+function ok(a, msg) {
+  window.parent.postMessage({ status: a ? "OK" : "KO", message: msg }, "*");
+}
+
+ok("BroadcastChannel" in window, "BroadcastChannel exists");
+
+var bc = new BroadcastChannel("foobar");
+ok(bc, "BroadcastChannel can be created");
+is(bc.name, "foobar", "BroadcastChannel.name is foobar");
+
+ok("postMessage" in bc, "BroadcastChannel has postMessage() method");
+
+bc.onmessage = function(evt) {
+  ok(evt instanceof MessageEvent, "evt is a MessageEvent");
+  is(evt.target, bc, "MessageEvent.target is bc");
+  is(evt.target.name, "foobar", "MessageEvent.target.name is foobar");
+  is(evt.target.name, bc.name, "MessageEvent.target.name is bc.name");
+  is(evt.data, "Hello world from the window!", "Message received from the window");
+  bc.postMessage("Hello world from the iframe!");
+};
+
+  </script>
+</body>
+</html>
diff --git a/dom/broadcastchannel/tests/iframe_mozbrowser.html b/dom/broadcastchannel/tests/iframe_mozbrowser.html
new file mode 100644
index 0000000000..adbb77a061
--- /dev/null
+++ b/dom/broadcastchannel/tests/iframe_mozbrowser.html
@@ -0,0 +1,15 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>MozBrowser iframe</title>
+</head>
+<body>
+  <script type="application/javascript">
+
+var bc = new BroadcastChannel("foobar");
+bc.postMessage("This is wrong!");
+
+  </script>
+</body>
+</html>
diff --git a/dom/broadcastchannel/tests/iframe_mozbrowser2.html b/dom/broadcastchannel/tests/iframe_mozbrowser2.html
new file mode 100644
index 0000000000..adbb77a061
--- /dev/null
+++ b/dom/broadcastchannel/tests/iframe_mozbrowser2.html
@@ -0,0 +1,15 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>MozBrowser iframe</title>
+</head>
+<body>
+  <script type="application/javascript">
+
+var bc = new BroadcastChannel("foobar");
+bc.postMessage("This is wrong!");
+
+  </script>
+</body>
+</html>
diff --git a/dom/broadcastchannel/tests/mochitest.ini b/dom/broadcastchannel/tests/mochitest.ini
new file mode 100644
index 0000000000..0955057195
--- /dev/null
+++ b/dom/broadcastchannel/tests/mochitest.ini
@@ -0,0 +1,28 @@
+[DEFAULT]
+support-files =
+  iframe_broadcastchannel.html
+  broadcastchannel_sharedWorker.js
+  broadcastchannel_worker_alive.js
+  !/dom/events/test/event_leak_utils.js
+  file_mozbrowser.html
+  file_mozbrowser2.html
+  iframe_mozbrowser.html
+  iframe_mozbrowser2.html
+  testUrl1_bfcache.html
+  testUrl2_bfcache.html
+
+[test_broadcastchannel_basic.html]
+skip-if =
+  http3
+[test_broadcastchannel_close.html]
+[test_broadcastchannel_self.html]
+[test_broadcastchannel_sharedWorker.html]
+[test_broadcastchannel_worker_alive.html]
+[test_bfcache.html]
+[test_event_listener_leaks.html]
+skip-if = (os == "win" && processor == "aarch64") #bug 1535784
+[test_invalidState.html]
+[test_ordering.html]
+[test_dataCloning.html]
+[test_dataURL.html]
+[test_message_after_close.html]
diff --git a/dom/broadcastchannel/tests/testUrl1_bfcache.html b/dom/broadcastchannel/tests/testUrl1_bfcache.html
new file mode 100644
index 0000000000..d31b13bd25
--- /dev/null
+++ b/dom/broadcastchannel/tests/testUrl1_bfcache.html
@@ -0,0 +1,18 @@
+<script>
+var bc = new BroadcastChannel("a");
+onpageshow = function(e) {
+  var bc1 = new BroadcastChannel("testUrl1_bfcache");
+  bc1.onmessage = function(event) {
+    if (event.data == "close") {
+      bc1.postMessage("closed");
+      bc1.close();
+      bc.close();
+      window.close();
+    } else if (event.data == "load") {
+      bc1.close();
+      location.href = "testUrl2_bfcache.html";
+    }
+  };
+  bc1.postMessage({type: e.type, persisted: e.persisted});
+};
+</script>
diff --git a/dom/broadcastchannel/tests/testUrl2_bfcache.html b/dom/broadcastchannel/tests/testUrl2_bfcache.html
new file mode 100644
index 0000000000..a1eed7927a
--- /dev/null
+++ b/dom/broadcastchannel/tests/testUrl2_bfcache.html
@@ -0,0 +1,12 @@
+<script>
+onpageshow = function(e) {
+  var bc2 = new BroadcastChannel("testUrl2_bfcache");
+  bc2.onmessage = function(event) {
+    if (event.data == "back") {
+      bc2.close();
+      history.back();
+    }
+  };
+  bc2.postMessage({type: e.type, persisted: e.persisted});
+};
+</script>
diff --git a/dom/broadcastchannel/tests/test_bfcache.html b/dom/broadcastchannel/tests/test_bfcache.html
new file mode 100644
index 0000000000..0197f343e2
--- /dev/null
+++ b/dom/broadcastchannel/tests/test_bfcache.html
@@ -0,0 +1,120 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>Test for bfcache and BroadcastChannel</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+  <script type="application/javascript">
+
+  /*
+   * The test opens a new window. Then a message 'load' is sent there to load
+   * another page. If expectedPersisted is false, a dummy message is sent
+   * through a BroadcastChannel which the first has registered to use.
+   * That should evict the page from bfcache.
+   * 'back' message is sent to call history.back().
+   * The page which is loaded from session history should be persisted if
+   * expectedPersisted is true.
+   */
+
+  SimpleTest.waitForExplicitFinish();
+  var testUrl1 = "testUrl1_bfcache.html";
+
+
+  function executeTest() {
+    var bc1 = new BroadcastChannel("testUrl1_bfcache");
+    var bc2 = new BroadcastChannel("testUrl2_bfcache");
+    bc1.onmessage = function(event) {
+      if (event.data == "closed") {
+        info("Closed");
+        runTest();
+        return;
+      }
+      page1Shown(event.data);
+    };
+    bc2.onmessage = function(event) { page2Shown(event.data); };
+
+    var counter = 0;
+    var expectedPersisted = false;
+    var bc = new BroadcastChannel("a");
+
+    function page1Shown(e) {
+      if (counter == 0) {
+        ok(!e.persisted, "test page should have been persisted initially");
+        bc1.postMessage("load");
+      } else {
+        is(e.persisted, expectedPersisted, "test page should have been persisted in pageshow");
+        bc1.postMessage("close");
+      }
+
+      counter++;
+    }
+
+    function page2Shown(e) {
+      if (!expectedPersisted) {
+        SimpleTest.executeSoon(function() {
+          info("Posting a message.");
+          bc.postMessage(42);
+        });
+      }
+
+      SimpleTest.executeSoon(function() {
+        info("Going back");
+        bc2.postMessage("back");
+      });
+    }
+
+    var tests = [
+      { expectedPersisted: true },
+      { expectedPersisted: false },
+    ];
+
+    function runTest() {
+      if (!tests.length) {
+        bc.close();
+        bc1.close();
+        bc2.close();
+        SimpleTest.finish();
+        return;
+      }
+
+      var test = tests.shift();
+
+      counter = 0;
+      expectedPersisted = test.expectedPersisted;
+      window.open(testUrl1, "", "noopener");
+    }
+
+
+    // If Fission is disabled, the pref is no-op.
+    SpecialPowers.pushPrefEnv({set: [["fission.bfcacheInParent", true]]}, () => {
+      runTest();
+    });
+
+  }
+
+  if (isXOrigin) {
+    // Bug 1746646: Make mochitests work with TCP enabled (cookieBehavior = 5)
+    // Acquire storage access permission here so that the BroadcastChannel used to
+    // communicate with the opened windows works in xorigin tests. Otherwise,
+    // the iframe containing this page is isolated from first-party storage access,
+    // which isolates BroadcastChannel communication.
+    SpecialPowers.wrap(document).notifyUserGestureActivation();
+    SpecialPowers.addPermission("storageAccessAPI", true, window.location.href).then(() => {
+      SpecialPowers.wrap(document).requestStorageAccess().then(() => {
+        SpecialPowers.pushPrefEnv({
+          set: [["privacy.partition.always_partition_third_party_non_cookie_storage", false]]
+        }).then(() => {
+          executeTest();
+        });
+      });
+    });
+  } else {
+    executeTest();
+  }
+
+  </script>
+</body>
+</html>
diff --git a/dom/broadcastchannel/tests/test_broadcastchannel_basic.html b/dom/broadcastchannel/tests/test_broadcastchannel_basic.html
new file mode 100644
index 0000000000..09196b0c52
--- /dev/null
+++ b/dom/broadcastchannel/tests/test_broadcastchannel_basic.html
@@ -0,0 +1,67 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for BroadcastChannel</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<div id="content"></div>
+
+<script type="application/javascript">
+
+function runTest() {
+  addEventListener("message", receiveMessage, false);
+  function receiveMessage(evt) {
+    if (evt.data.status == "OK") {
+      ok(true, evt.data.message);
+    } else if (evt.data.status == "KO") {
+      ok(false, evt.data.message);
+    } else {
+      ok(false, "Unknown message");
+    }
+  }
+
+  ok("BroadcastChannel" in window, "BroadcastChannel exists");
+
+  var bc = new BroadcastChannel("foobar");
+  ok(bc, "BroadcastChannel can be created");
+  is(bc.name, "foobar", "BroadcastChannel.name is foobar");
+
+  ok("postMessage" in bc, "BroadcastChannel has postMessage() method");
+
+  bc.onmessage = function(evt) {
+    ok(evt instanceof MessageEvent, "This is a MessageEvent");
+    is(evt.target, bc, "MessageEvent.target is bc");
+    is(evt.target.name, "foobar", "MessageEvent.target.name is foobar");
+    is(evt.target.name, bc.name, "MessageEvent.target.name == bc.name");
+    ok(evt.origin.indexOf("http://mochi.test:8888") == 0, "MessageEvent.origin is correct");
+    is(evt.data, "Hello world from the iframe!", "The message from the iframe has been received!");
+    SimpleTest.finish();
+  };
+
+  var div = document.getElementById("content");
+  ok(div, "Parent exists");
+
+  var ifr = document.createElement("iframe");
+  ifr.addEventListener("load", iframeLoaded);
+  ifr.setAttribute("src", "iframe_broadcastchannel.html");
+  div.appendChild(ifr);
+
+  function iframeLoaded() {
+    bc.postMessage("Hello world from the window!");
+  }
+
+  // A leak test
+  var dummyBc = new BroadcastChannel("dont_leak_this");
+  dummyBc.foo = "bar";
+  // don't add message listener!
+}
+
+SimpleTest.waitForExplicitFinish();
+runTest();
+
+</script>
+</body>
+</html>
diff --git a/dom/broadcastchannel/tests/test_broadcastchannel_close.html b/dom/broadcastchannel/tests/test_broadcastchannel_close.html
new file mode 100644
index 0000000000..91cb9c92a4
--- /dev/null
+++ b/dom/broadcastchannel/tests/test_broadcastchannel_close.html
@@ -0,0 +1,61 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for BroadcastChannel</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<div id="content"></div>
+
+<script type="application/javascript">
+
+function runTest() {
+  var receiver = new BroadcastChannel("foo");
+  var sequence = [ "2", "done" ];
+  receiver.onmessage = function(e) {
+    if (!sequence.length) {
+      ok(false, "No more data is expected");
+      return;
+    }
+
+    var data = sequence.shift();
+    is(e.data, data);
+
+    if (!sequence.length) {
+      SimpleTest.executeSoon(function() {
+        SimpleTest.finish();
+      });
+    }
+  };
+
+  var x = new BroadcastChannel("foo");
+  x.close();
+  try {
+    x.postMessage("1");
+    ok(false, "PostMessage should throw if called after a close().");
+  } catch (e) {
+    ok(true, "PostMessage should throw if called after a close().");
+  }
+
+  var y = new BroadcastChannel("foo");
+  y.postMessage("2");
+  y.close();
+  try {
+    y.postMessage("3");
+    ok(false, "PostMessage should throw if called after a close().");
+  } catch (e) {
+    ok(true, "PostMessage should throw if called after a close().");
+  }
+
+  var z = new BroadcastChannel("foo");
+  z.postMessage("done");
+}
+
+SimpleTest.waitForExplicitFinish();
+runTest();
+
+</script>
+</body>
+</html>
diff --git a/dom/broadcastchannel/tests/test_broadcastchannel_self.html b/dom/broadcastchannel/tests/test_broadcastchannel_self.html
new file mode 100644
index 0000000000..501f71f09c
--- /dev/null
+++ b/dom/broadcastchannel/tests/test_broadcastchannel_self.html
@@ -0,0 +1,37 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for BroadcastChannel</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<div id="content"></div>
+
+<script type="application/javascript">
+
+function runTest() {
+  let x = new BroadcastChannel("foo");
+  let y = new BroadcastChannel("foo");
+
+  function func(e) {
+    is(e.target, y, "The target is !x");
+
+    SimpleTest.executeSoon(function() {
+      SimpleTest.finish();
+    });
+  }
+
+  x.onmessage = func;
+  y.onmessage = func;
+
+  x.postMessage("foo");
+}
+
+SimpleTest.waitForExplicitFinish();
+runTest();
+
+</script>
+</body>
+</html>
diff --git a/dom/broadcastchannel/tests/test_broadcastchannel_sharedWorker.html b/dom/broadcastchannel/tests/test_broadcastchannel_sharedWorker.html
new file mode 100644
index 0000000000..f76c17cbd8
--- /dev/null
+++ b/dom/broadcastchannel/tests/test_broadcastchannel_sharedWorker.html
@@ -0,0 +1,52 @@
+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<!DOCTYPE HTML>
+<html>
+<!--
+Tests of DOM BroadcastChannel in SharedWorkers
+-->
+<head>
+  <title>Test for BroadcastChannel in SharedWorkers</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+<script class="testbody" language="javascript">
+
+function runTests() {
+  var worker = new SharedWorker("broadcastchannel_sharedWorker.js");
+
+  var bc = new BroadcastChannel("foobar");
+
+  worker.port.onmessage = function(event) {
+    if (event.data == "READY") {
+      ok(true, "SharedWorker is ready!");
+      bc.postMessage("hello world from the window");
+    } else {
+      ok(false, "Something wrong happened");
+    }
+  };
+
+  bc.onmessage = function(event) {
+    is("hello world from the worker", event.data, "The message matches!");
+    bc.close();
+    SimpleTest.finish();
+  };
+
+  worker.port.postMessage("go");
+}
+
+SimpleTest.waitForExplicitFinish();
+runTests();
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/broadcastchannel/tests/test_broadcastchannel_worker_alive.html b/dom/broadcastchannel/tests/test_broadcastchannel_worker_alive.html
new file mode 100644
index 0000000000..3667c8ae9d
--- /dev/null
+++ b/dom/broadcastchannel/tests/test_broadcastchannel_worker_alive.html
@@ -0,0 +1,56 @@
+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<!DOCTYPE HTML>
+<html>
+<!--
+Tests of DOM BroadcastChannel in workers
+-->
+<head>
+  <title>Test for BroadcastChannel in workers</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+<script class="testbody" language="javascript">
+
+function runTests() {
+  var id = 0;
+  (new BroadcastChannel("foobar")).onmessage = function(event) {
+    info("MSG: " + event.data);
+
+    if (event.data == "READY") {
+      ok(true, "Worker is ready!");
+    } else {
+      is(id, event.data, "The message is correct: " + id);
+    }
+
+    for (var i = 0; i < 3; ++i) {
+      SpecialPowers.forceCC();
+      SpecialPowers.forceGC();
+    }
+
+    if (id == 5) {
+      SimpleTest.finish();
+      return;
+    }
+
+    event.target.postMessage(++id);
+  };
+
+  new Worker("broadcastchannel_worker_alive.js");
+}
+
+SimpleTest.waitForExplicitFinish();
+runTests();
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/broadcastchannel/tests/test_dataCloning.html b/dom/broadcastchannel/tests/test_dataCloning.html
new file mode 100644
index 0000000000..26c1ce370a
--- /dev/null
+++ b/dom/broadcastchannel/tests/test_dataCloning.html
@@ -0,0 +1,27 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for BroadcastChannel.postMessage invalid State</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<div id="content"></div>
+
+<script type="application/javascript">
+
+
+let c = new BroadcastChannel("foo");
+
+try {
+  c.postMessage(Symbol());
+  ok(false, "This should throw!");
+} catch (e) {
+  ok(true, "This should throw!");
+  is(e.name, "DataCloneError", "Correct DataCloneError exception thrown");
+}
+
+</script>
+</body>
+</html>
diff --git a/dom/broadcastchannel/tests/test_dataURL.html b/dom/broadcastchannel/tests/test_dataURL.html
new file mode 100644
index 0000000000..f4f9c71db3
--- /dev/null
+++ b/dom/broadcastchannel/tests/test_dataURL.html
@@ -0,0 +1,35 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for BroadcastChannel in data: URL</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<div id="dataURL">
+var a = new BroadcastChannel('a');
+var b = new BroadcastChannel('a');
+a.onmessage = function(e) { parent.postMessage(e.data, "*"); };
+b.postMessage(42);
+</div>
+
+<script>
+
+SimpleTest.waitForExplicitFinish();
+
+onmessage = function(e) {
+  is(e.data, 42, "BroadcastChannel works with data URLs");
+  SimpleTest.finish();
+};
+
+// eslint-disable-next-line no-useless-concat
+var url = "data:text/html,<script>" + document.getElementById("dataURL").textContent + "</" + "script>";
+
+var ifr = document.createElement("iframe");
+document.body.appendChild(ifr);
+
+ifr.setAttribute("sandbox", "allow-scripts");
+ifr.src = url;
+</script>
+</body>
+</html>
diff --git a/dom/broadcastchannel/tests/test_event_listener_leaks.html b/dom/broadcastchannel/tests/test_event_listener_leaks.html
new file mode 100644
index 0000000000..33568913fc
--- /dev/null
+++ b/dom/broadcastchannel/tests/test_event_listener_leaks.html
@@ -0,0 +1,55 @@
+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Bug 1450358 - Test BroadcastChannel event listener leak conditions</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="/tests/dom/events/test/event_leak_utils.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<script class="testbody" type="text/javascript">
+// Manipulate BroadcastChannel objects in the frame's context.
+// Its important here that we create a listener callback from
+// the DOM objects back to the frame's global in order to
+// exercise the leak condition.
+let count = 0;
+async function useBroadcastChannel(contentWindow) {
+  contentWindow.messageCount = 0;
+
+  count += 1;
+  const name = `test_event_listener_leaks-${count}`;
+
+  let bc = new contentWindow.BroadcastChannel(name);
+  let outer = new BroadcastChannel(name);
+  outer.postMessage("foo");
+
+  await new Promise(resolve => {
+    bc.onmessage = e => {
+      contentWindow.messageCount += 1;
+      resolve();
+    };
+  });
+
+  is(contentWindow.messageCount, 1, "message should be received");
+}
+
+async function runTest() {
+  try {
+    await checkForEventListenerLeaks("BroadcastChannel", useBroadcastChannel);
+  } catch (e) {
+    ok(false, e);
+  } finally {
+    SimpleTest.finish();
+  }
+}
+
+SimpleTest.waitForExplicitFinish();
+addEventListener("load", runTest, { once: true });
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/broadcastchannel/tests/test_invalidState.html b/dom/broadcastchannel/tests/test_invalidState.html
new file mode 100644
index 0000000000..371a58768a
--- /dev/null
+++ b/dom/broadcastchannel/tests/test_invalidState.html
@@ -0,0 +1,27 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for BroadcastChannel.postMessage invalid State</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<div id="content"></div>
+
+<script type="application/javascript">
+
+var c = new BroadcastChannel("foo");
+c.close();
+
+try {
+  c.postMessage("bar");
+  ok(false, "This should throw!");
+} catch (e) {
+  ok(true, "This should throw!");
+  is(e.name, "InvalidStateError", "Correct invalid-state exception thrown");
+}
+
+</script>
+</body>
+</html>
diff --git a/dom/broadcastchannel/tests/test_message_after_close.html b/dom/broadcastchannel/tests/test_message_after_close.html
new file mode 100644
index 0000000000..1ef8a018ea
--- /dev/null
+++ b/dom/broadcastchannel/tests/test_message_after_close.html
@@ -0,0 +1,31 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for BroadcastChannel - message after close</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<script>
+SimpleTest.waitForExplicitFinish();
+
+let a = new BroadcastChannel('a');
+let b = new BroadcastChannel('a');
+let count = 0;
+
+a.onmessage = function(e) {
+  ++count;
+  a.close();
+
+  setTimeout(() => {
+    is(count, 1, "Only 1 message received");
+    SimpleTest.finish();
+  }, 0);
+}
+
+for (let i = 0; i < 100; ++i) {
+  b.postMessage(42);
+}
+</script>
+</body>
+</html>
diff --git a/dom/broadcastchannel/tests/test_ordering.html b/dom/broadcastchannel/tests/test_ordering.html
new file mode 100644
index 0000000000..5dd36bc77d
--- /dev/null
+++ b/dom/broadcastchannel/tests/test_ordering.html
@@ -0,0 +1,64 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for BroadcastChannel.postMessage invalid State</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<div id="content"></div>
+
+<script type="application/javascript">
+
+let c1 = new BroadcastChannel("order");
+let c2 = new BroadcastChannel("order");
+let c3 = new BroadcastChannel("order");
+
+let events = [];
+let doneCount = 0;
+
+function whichBC(bc) {
+  if (bc == c1) return "c1";
+  if (bc == c2) return "c2";
+  if (bc == c3) return "c3";
+  return "What?!?";
+}
+
+function handler(e) {
+  events.push(e);
+  if (e.data == "done") {
+    doneCount++;
+    if (doneCount == 2) {
+      is(events.length, 6, "Correct length");
+      is(whichBC(events[0].target), "c2", "target for event 0");
+      is(events[0].data, "from c1");
+      is(whichBC(events[1].target), "c3", "target for event 1");
+      is(events[1].data, "from c1");
+      is(whichBC(events[2].target), "c1", "target for event 2");
+      is(events[2].data, "from c3");
+      is(whichBC(events[3].target), "c2", "target for event 3");
+      is(events[3].data, "from c3");
+      is(whichBC(events[4].target), "c1", "target for event 4");
+      is(events[4].data, "done");
+      is(whichBC(events[5].target), "c3", "target for event 5");
+      is(events[5].data, "done");
+
+      SimpleTest.finish();
+    }
+  }
+}
+
+c1.onmessage = handler;
+c2.onmessage = handler;
+c3.onmessage = handler;
+
+c1.postMessage("from c1");
+c3.postMessage("from c3");
+c2.postMessage("done");
+
+SimpleTest.waitForExplicitFinish();
+
+</script>
+</body>
+</html>