1 files changed, 659 insertions, 0 deletions
diff --git a/dom/base/ScreenOrientation.cpp b/dom/base/ScreenOrientation.cpp
new file mode 100644
index 0000000000..eb93f68752
--- /dev/null
+++ b/dom/base/ScreenOrientation.cpp
@@ -0,0 +1,659 @@
+/* -*- 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 "ScreenOrientation.h"
+#include "nsIDocShell.h"
+#include "mozilla/dom/Document.h"
+#include "nsGlobalWindow.h"
+#include "nsSandboxFlags.h"
+#include "nsScreen.h"
+
+#include "mozilla/DOMEventTargetHelper.h"
+#include "mozilla/Hal.h"
+#include "mozilla/Preferences.h"
+
+#include "mozilla/dom/ContentChild.h"
+#include "mozilla/dom/Event.h"
+#include "mozilla/dom/Promise.h"
+#include "nsContentUtils.h"
+
+using namespace mozilla;
+using namespace mozilla::dom;
+
+NS_IMPL_CYCLE_COLLECTION_INHERITED(ScreenOrientation, DOMEventTargetHelper,
+                                   mScreen);
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ScreenOrientation)
+NS_INTERFACE_MAP_END_INHERITING(DOMEventTargetHelper)
+
+NS_IMPL_ADDREF_INHERITED(ScreenOrientation, DOMEventTargetHelper)
+NS_IMPL_RELEASE_INHERITED(ScreenOrientation, DOMEventTargetHelper)
+
+static OrientationType InternalOrientationToType(
+    hal::ScreenOrientation aOrientation) {
+  switch (aOrientation) {
+    case hal::eScreenOrientation_PortraitPrimary:
+      return OrientationType::Portrait_primary;
+    case hal::eScreenOrientation_PortraitSecondary:
+      return OrientationType::Portrait_secondary;
+    case hal::eScreenOrientation_LandscapePrimary:
+      return OrientationType::Landscape_primary;
+    case hal::eScreenOrientation_LandscapeSecondary:
+      return OrientationType::Landscape_secondary;
+    default:
+      MOZ_CRASH("Bad aOrientation value");
+  }
+}
+
+static hal::ScreenOrientation OrientationTypeToInternal(
+    OrientationType aOrientation) {
+  switch (aOrientation) {
+    case OrientationType::Portrait_primary:
+      return hal::eScreenOrientation_PortraitPrimary;
+    case OrientationType::Portrait_secondary:
+      return hal::eScreenOrientation_PortraitSecondary;
+    case OrientationType::Landscape_primary:
+      return hal::eScreenOrientation_LandscapePrimary;
+    case OrientationType::Landscape_secondary:
+      return hal::eScreenOrientation_LandscapeSecondary;
+    default:
+      MOZ_CRASH("Bad aOrientation value");
+  }
+}
+
+ScreenOrientation::ScreenOrientation(nsPIDOMWindowInner* aWindow,
+                                     nsScreen* aScreen)
+    : DOMEventTargetHelper(aWindow), mScreen(aScreen) {
+  MOZ_ASSERT(aWindow);
+  MOZ_ASSERT(aScreen);
+
+  hal::RegisterScreenConfigurationObserver(this);
+
+  hal::ScreenConfiguration config;
+  hal::GetCurrentScreenConfiguration(&config);
+  mType = InternalOrientationToType(config.orientation());
+  mAngle = config.angle();
+
+  Document* doc = GetResponsibleDocument();
+  BrowsingContext* bc = doc ? doc->GetBrowsingContext() : nullptr;
+  if (bc && !bc->IsDiscarded() && !bc->InRDMPane()) {
+    MOZ_ALWAYS_SUCCEEDS(bc->SetCurrentOrientation(mType, mAngle));
+  }
+}
+
+ScreenOrientation::~ScreenOrientation() {
+  UnlockDeviceOrientation();
+  hal::UnregisterScreenConfigurationObserver(this);
+  MOZ_ASSERT(!mFullscreenListener);
+}
+
+class ScreenOrientation::FullscreenEventListener final
+    : public nsIDOMEventListener {
+  ~FullscreenEventListener() = default;
+
+ public:
+  FullscreenEventListener() = default;
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIDOMEVENTLISTENER
+};
+
+class ScreenOrientation::VisibleEventListener final
+    : public nsIDOMEventListener {
+  ~VisibleEventListener() = default;
+
+ public:
+  VisibleEventListener() = default;
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIDOMEVENTLISTENER
+};
+
+class ScreenOrientation::LockOrientationTask final : public nsIRunnable {
+  ~LockOrientationTask();
+
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIRUNNABLE
+
+  LockOrientationTask(ScreenOrientation* aScreenOrientation, Promise* aPromise,
+                      hal::ScreenOrientation aOrientationLock,
+                      Document* aDocument, bool aIsFullscreen);
+
+ protected:
+  bool OrientationLockContains(OrientationType aOrientationType);
+
+  RefPtr<ScreenOrientation> mScreenOrientation;
+  RefPtr<Promise> mPromise;
+  hal::ScreenOrientation mOrientationLock;
+  nsCOMPtr<Document> mDocument;
+  bool mIsFullscreen;
+};
+
+NS_IMPL_ISUPPORTS(ScreenOrientation::LockOrientationTask, nsIRunnable)
+
+ScreenOrientation::LockOrientationTask::LockOrientationTask(
+    ScreenOrientation* aScreenOrientation, Promise* aPromise,
+    hal::ScreenOrientation aOrientationLock, Document* aDocument,
+    bool aIsFullscreen)
+    : mScreenOrientation(aScreenOrientation),
+      mPromise(aPromise),
+      mOrientationLock(aOrientationLock),
+      mDocument(aDocument),
+      mIsFullscreen(aIsFullscreen) {
+  MOZ_ASSERT(aScreenOrientation);
+  MOZ_ASSERT(aPromise);
+  MOZ_ASSERT(aDocument);
+}
+
+ScreenOrientation::LockOrientationTask::~LockOrientationTask() = default;
+
+bool ScreenOrientation::LockOrientationTask::OrientationLockContains(
+    OrientationType aOrientationType) {
+  return mOrientationLock & OrientationTypeToInternal(aOrientationType);
+}
+
+NS_IMETHODIMP
+ScreenOrientation::LockOrientationTask::Run() {
+  // Step to lock the orientation as defined in the spec.
+
+  if (mDocument->GetOrientationPendingPromise() != mPromise) {
+    // The document's pending promise is not associated with this task
+    // to lock orientation. There has since been another request to
+    // lock orientation, thus we don't need to do anything. Old promise
+    // should be been rejected.
+    return NS_OK;
+  }
+
+  if (mDocument->Hidden()) {
+    // Active orientation lock is not the document's orientation lock.
+    mPromise->MaybeResolveWithUndefined();
+    mDocument->ClearOrientationPendingPromise();
+    return NS_OK;
+  }
+
+  if (mOrientationLock == hal::eScreenOrientation_None) {
+    mScreenOrientation->UnlockDeviceOrientation();
+    mPromise->MaybeResolveWithUndefined();
+    mDocument->ClearOrientationPendingPromise();
+    return NS_OK;
+  }
+
+  ErrorResult rv;
+  bool result = mScreenOrientation->LockDeviceOrientation(mOrientationLock,
+                                                          mIsFullscreen, rv);
+  if (NS_WARN_IF(rv.Failed())) {
+    return rv.StealNSResult();
+  }
+
+  if (NS_WARN_IF(!result)) {
+    mPromise->MaybeReject(NS_ERROR_UNEXPECTED);
+    mDocument->ClearOrientationPendingPromise();
+    return NS_OK;
+  }
+
+  BrowsingContext* bc = mDocument->GetBrowsingContext();
+  if (OrientationLockContains(bc->GetCurrentOrientationType()) ||
+      (mOrientationLock == hal::eScreenOrientation_Default &&
+       bc->GetCurrentOrientationAngle() == 0)) {
+    // Orientation lock will not cause an orientation change.
+    mPromise->MaybeResolveWithUndefined();
+    mDocument->ClearOrientationPendingPromise();
+  }
+
+  return NS_OK;
+}
+
+already_AddRefed<Promise> ScreenOrientation::Lock(
+    OrientationLockType aOrientation, ErrorResult& aRv) {
+  hal::ScreenOrientation orientation = hal::eScreenOrientation_None;
+
+  switch (aOrientation) {
+    case OrientationLockType::Any:
+      orientation = hal::eScreenOrientation_PortraitPrimary |
+                    hal::eScreenOrientation_PortraitSecondary |
+                    hal::eScreenOrientation_LandscapePrimary |
+                    hal::eScreenOrientation_LandscapeSecondary;
+      break;
+    case OrientationLockType::Natural:
+      orientation |= hal::eScreenOrientation_Default;
+      break;
+    case OrientationLockType::Landscape:
+      orientation = hal::eScreenOrientation_LandscapePrimary |
+                    hal::eScreenOrientation_LandscapeSecondary;
+      break;
+    case OrientationLockType::Portrait:
+      orientation = hal::eScreenOrientation_PortraitPrimary |
+                    hal::eScreenOrientation_PortraitSecondary;
+      break;
+    case OrientationLockType::Portrait_primary:
+      orientation = hal::eScreenOrientation_PortraitPrimary;
+      break;
+    case OrientationLockType::Portrait_secondary:
+      orientation = hal::eScreenOrientation_PortraitSecondary;
+      break;
+    case OrientationLockType::Landscape_primary:
+      orientation = hal::eScreenOrientation_LandscapePrimary;
+      break;
+    case OrientationLockType::Landscape_secondary:
+      orientation = hal::eScreenOrientation_LandscapeSecondary;
+      break;
+    default:
+      NS_WARNING("Unexpected orientation type");
+      aRv.Throw(NS_ERROR_UNEXPECTED);
+      return nullptr;
+  }
+
+  return LockInternal(orientation, aRv);
+}
+
+void ScreenOrientation::AbortInProcessOrientationPromises(
+    BrowsingContext* aBrowsingContext) {
+  MOZ_ASSERT(aBrowsingContext);
+
+  aBrowsingContext = aBrowsingContext->Top();
+  aBrowsingContext->PreOrderWalk([](BrowsingContext* aContext) {
+    nsIDocShell* docShell = aContext->GetDocShell();
+    if (docShell) {
+      Document* doc = docShell->GetDocument();
+      if (doc) {
+        Promise* promise = doc->GetOrientationPendingPromise();
+        if (promise) {
+          promise->MaybeReject(NS_ERROR_DOM_ABORT_ERR);
+          doc->ClearOrientationPendingPromise();
+        }
+      }
+    }
+  });
+}
+
+already_AddRefed<Promise> ScreenOrientation::LockInternal(
+    hal::ScreenOrientation aOrientation, ErrorResult& aRv) {
+  // Steps to apply an orientation lock as defined in spec.
+
+  Document* doc = GetResponsibleDocument();
+  if (NS_WARN_IF(!doc)) {
+    aRv.Throw(NS_ERROR_UNEXPECTED);
+    return nullptr;
+  }
+
+  nsCOMPtr<nsPIDOMWindowInner> owner = GetOwner();
+  if (NS_WARN_IF(!owner)) {
+    aRv.Throw(NS_ERROR_UNEXPECTED);
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIDocShell> docShell = owner->GetDocShell();
+  if (NS_WARN_IF(!docShell)) {
+    aRv.Throw(NS_ERROR_UNEXPECTED);
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIGlobalObject> go = do_QueryInterface(owner);
+  MOZ_ASSERT(go);
+  RefPtr<Promise> p = Promise::Create(go, aRv);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+
+#if !defined(MOZ_WIDGET_ANDROID)
+  // User agent does not support locking the screen orientation.
+  p->MaybeReject(NS_ERROR_DOM_NOT_SUPPORTED_ERR);
+  return p.forget();
+#else
+  LockPermission perm = GetLockOrientationPermission(true);
+  if (perm == LOCK_DENIED) {
+    p->MaybeReject(NS_ERROR_DOM_SECURITY_ERR);
+    return p.forget();
+  }
+
+  RefPtr<BrowsingContext> bc = docShell->GetBrowsingContext();
+  bc = bc ? bc->Top() : nullptr;
+  if (!bc) {
+    aRv.Throw(NS_ERROR_UNEXPECTED);
+    return nullptr;
+  }
+
+  bc->SetOrientationLock(aOrientation, aRv);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  AbortInProcessOrientationPromises(bc);
+  dom::ContentChild::GetSingleton()->SendAbortOtherOrientationPendingPromises(
+      bc);
+
+  if (!doc->SetOrientationPendingPromise(p)) {
+    p->MaybeReject(NS_ERROR_DOM_SECURITY_ERR);
+    return p.forget();
+  }
+
+  nsCOMPtr<nsIRunnable> lockOrientationTask = new LockOrientationTask(
+      this, p, aOrientation, doc, perm == FULLSCREEN_LOCK_ALLOWED);
+  aRv = NS_DispatchToMainThread(lockOrientationTask);
+  if (NS_WARN_IF(aRv.Failed())) {
+    return nullptr;
+  }
+
+  return p.forget();
+#endif
+}
+
+bool ScreenOrientation::LockDeviceOrientation(
+    hal::ScreenOrientation aOrientation, bool aIsFullscreen, ErrorResult& aRv) {
+  if (!GetOwner()) {
+    aRv.Throw(NS_ERROR_UNEXPECTED);
+    return false;
+  }
+
+  nsCOMPtr<EventTarget> target = GetOwner()->GetDoc();
+  // We need to register a listener so we learn when we leave fullscreen
+  // and when we will have to unlock the screen.
+  // This needs to be done before LockScreenOrientation call to make sure
+  // the locking can be unlocked.
+  if (aIsFullscreen && !target) {
+    return false;
+  }
+
+  if (NS_WARN_IF(!hal::LockScreenOrientation(aOrientation))) {
+    return false;
+  }
+
+  // We are fullscreen and lock has been accepted.
+  if (aIsFullscreen) {
+    if (!mFullscreenListener) {
+      mFullscreenListener = new FullscreenEventListener();
+    }
+
+    aRv = target->AddSystemEventListener(u"fullscreenchange"_ns,
+                                         mFullscreenListener,
+                                         /* useCapture = */ true);
+    if (NS_WARN_IF(aRv.Failed())) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+void ScreenOrientation::Unlock(ErrorResult& aRv) {
+  RefPtr<Promise> p = LockInternal(hal::eScreenOrientation_None, aRv);
+}
+
+void ScreenOrientation::UnlockDeviceOrientation() {
+  hal::UnlockScreenOrientation();
+
+  if (!mFullscreenListener || !GetOwner()) {
+    mFullscreenListener = nullptr;
+    return;
+  }
+
+  // Remove event listener in case of fullscreen lock.
+  nsCOMPtr<EventTarget> target = GetOwner()->GetDoc();
+  if (target) {
+    target->RemoveSystemEventListener(u"fullscreenchange"_ns,
+                                      mFullscreenListener,
+                                      /* useCapture */ true);
+  }
+
+  mFullscreenListener = nullptr;
+}
+
+OrientationType ScreenOrientation::DeviceType(CallerType aCallerType) const {
+  return nsContentUtils::ResistFingerprinting(aCallerType)
+             ? OrientationType::Landscape_primary
+             : mType;
+}
+
+uint16_t ScreenOrientation::DeviceAngle(CallerType aCallerType) const {
+  return nsContentUtils::ResistFingerprinting(aCallerType) ? 0 : mAngle;
+}
+
+OrientationType ScreenOrientation::GetType(CallerType aCallerType,
+                                           ErrorResult& aRv) const {
+  if (nsContentUtils::ResistFingerprinting(aCallerType)) {
+    return OrientationType::Landscape_primary;
+  }
+
+  Document* doc = GetResponsibleDocument();
+  BrowsingContext* bc = doc ? doc->GetBrowsingContext() : nullptr;
+  if (!bc) {
+    aRv.Throw(NS_ERROR_UNEXPECTED);
+    return OrientationType::Portrait_primary;
+  }
+
+  return bc->GetCurrentOrientationType();
+}
+
+uint16_t ScreenOrientation::GetAngle(CallerType aCallerType,
+                                     ErrorResult& aRv) const {
+  if (nsContentUtils::ResistFingerprinting(aCallerType)) {
+    return 0;
+  }
+
+  Document* doc = GetResponsibleDocument();
+  BrowsingContext* bc = doc ? doc->GetBrowsingContext() : nullptr;
+  if (!bc) {
+    aRv.Throw(NS_ERROR_UNEXPECTED);
+    return 0;
+  }
+
+  return bc->GetCurrentOrientationAngle();
+}
+
+ScreenOrientation::LockPermission
+ScreenOrientation::GetLockOrientationPermission(bool aCheckSandbox) const {
+  nsCOMPtr<nsPIDOMWindowInner> owner = GetOwner();
+  if (!owner) {
+    return LOCK_DENIED;
+  }
+
+  // Chrome can always lock the screen orientation.
+  if (owner->GetBrowsingContext()->IsChrome()) {
+    return LOCK_ALLOWED;
+  }
+
+  nsCOMPtr<Document> doc = owner->GetDoc();
+  if (!doc || doc->Hidden()) {
+    return LOCK_DENIED;
+  }
+
+  // Sandboxed without "allow-orientation-lock"
+  if (aCheckSandbox && doc->GetSandboxFlags() & SANDBOXED_ORIENTATION_LOCK) {
+    return LOCK_DENIED;
+  }
+
+  if (Preferences::GetBool(
+          "dom.screenorientation.testing.non_fullscreen_lock_allow", false)) {
+    return LOCK_ALLOWED;
+  }
+
+  // Other content must be fullscreen in order to lock orientation.
+  return doc->Fullscreen() ? FULLSCREEN_LOCK_ALLOWED : LOCK_DENIED;
+}
+
+Document* ScreenOrientation::GetResponsibleDocument() const {
+  nsCOMPtr<nsPIDOMWindowInner> owner = GetOwner();
+  if (!owner) {
+    return nullptr;
+  }
+
+  return owner->GetDoc();
+}
+
+void ScreenOrientation::Notify(const hal::ScreenConfiguration& aConfiguration) {
+  if (ShouldResistFingerprinting()) {
+    return;
+  }
+
+  Document* doc = GetResponsibleDocument();
+  BrowsingContext* bc = doc ? doc->GetBrowsingContext() : nullptr;
+  if (!bc) {
+    return;
+  }
+
+  hal::ScreenOrientation orientation = aConfiguration.orientation();
+  if (orientation != hal::eScreenOrientation_PortraitPrimary &&
+      orientation != hal::eScreenOrientation_PortraitSecondary &&
+      orientation != hal::eScreenOrientation_LandscapePrimary &&
+      orientation != hal::eScreenOrientation_LandscapeSecondary) {
+    // The platform may notify of some other values from
+    // an orientation lock, but we only care about real
+    // changes to screen orientation which result in one of
+    // the values we care about.
+    return;
+  }
+
+  OrientationType previousOrientation = mType;
+  mAngle = aConfiguration.angle();
+  mType = InternalOrientationToType(orientation);
+
+  DebugOnly<nsresult> rv;
+  if (mScreen && mType != previousOrientation) {
+    // Use of mozorientationchange is deprecated.
+    rv = mScreen->DispatchTrustedEvent(u"mozorientationchange"_ns);
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "DispatchTrustedEvent failed");
+  }
+
+  if (doc->Hidden() && !mVisibleListener) {
+    mVisibleListener = new VisibleEventListener();
+    rv = doc->AddSystemEventListener(u"visibilitychange"_ns, mVisibleListener,
+                                     /* useCapture = */ true);
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "AddSystemEventListener failed");
+    return;
+  }
+
+  if (mType != bc->GetCurrentOrientationType()) {
+    rv = bc->SetCurrentOrientation(mType, mAngle);
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "SetCurrentOrientation failed");
+
+    nsCOMPtr<nsIRunnable> runnable = DispatchChangeEventAndResolvePromise();
+    rv = NS_DispatchToMainThread(runnable);
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "NS_DispatchToMainThread failed");
+  }
+}
+
+void ScreenOrientation::UpdateActiveOrientationLock(
+    hal::ScreenOrientation aOrientation) {
+  if (aOrientation == hal::eScreenOrientation_None) {
+    hal::UnlockScreenOrientation();
+  } else {
+    DebugOnly<bool> ok = hal::LockScreenOrientation(aOrientation);
+    NS_WARNING_ASSERTION(ok, "hal::LockScreenOrientation failed");
+  }
+}
+
+nsCOMPtr<nsIRunnable>
+ScreenOrientation::DispatchChangeEventAndResolvePromise() {
+  RefPtr<Document> doc = GetResponsibleDocument();
+  RefPtr<ScreenOrientation> self = this;
+  return NS_NewRunnableFunction(
+      "dom::ScreenOrientation::DispatchChangeEvent", [self, doc]() {
+        DebugOnly<nsresult> rv = self->DispatchTrustedEvent(u"change"_ns);
+        NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "DispatchTrustedEvent failed");
+        if (doc) {
+          Promise* pendingPromise = doc->GetOrientationPendingPromise();
+          if (pendingPromise) {
+            pendingPromise->MaybeResolveWithUndefined();
+            doc->ClearOrientationPendingPromise();
+          }
+        }
+      });
+}
+
+JSObject* ScreenOrientation::WrapObject(JSContext* aCx,
+                                        JS::Handle<JSObject*> aGivenProto) {
+  return ScreenOrientation_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+bool ScreenOrientation::ShouldResistFingerprinting() const {
+  bool resist = false;
+  if (nsCOMPtr<nsPIDOMWindowInner> owner = GetOwner()) {
+    resist = nsContentUtils::ShouldResistFingerprinting(owner->GetDocShell());
+  }
+  return resist;
+}
+
+NS_IMPL_ISUPPORTS(ScreenOrientation::VisibleEventListener, nsIDOMEventListener)
+
+NS_IMETHODIMP
+ScreenOrientation::VisibleEventListener::HandleEvent(Event* aEvent) {
+  // Document may have become visible, if the page is visible, run the steps
+  // following the "now visible algorithm" as specified.
+  nsCOMPtr<EventTarget> target = aEvent->GetCurrentTarget();
+  MOZ_ASSERT(target);
+
+  nsCOMPtr<Document> doc = do_QueryInterface(target);
+  if (!doc || doc->Hidden()) {
+    return NS_OK;
+  }
+
+  auto* win = nsGlobalWindowInner::Cast(doc->GetInnerWindow());
+  if (!win) {
+    return NS_OK;
+  }
+
+  ErrorResult rv;
+  nsScreen* screen = win->GetScreen(rv);
+  if (NS_WARN_IF(rv.Failed())) {
+    return rv.StealNSResult();
+  }
+
+  MOZ_ASSERT(screen);
+  ScreenOrientation* orientation = screen->Orientation();
+  MOZ_ASSERT(orientation);
+
+  target->RemoveSystemEventListener(u"visibilitychange"_ns, this, true);
+
+  BrowsingContext* bc = doc->GetBrowsingContext();
+  if (bc && bc->GetCurrentOrientationType() !=
+                orientation->DeviceType(CallerType::System)) {
+    nsresult result =
+        bc->SetCurrentOrientation(orientation->DeviceType(CallerType::System),
+                                  orientation->DeviceAngle(CallerType::System));
+    NS_ENSURE_SUCCESS(result, result);
+
+    nsCOMPtr<nsIRunnable> runnable =
+        orientation->DispatchChangeEventAndResolvePromise();
+    rv = NS_DispatchToMainThread(runnable);
+    if (NS_WARN_IF(rv.Failed())) {
+      return rv.StealNSResult();
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMPL_ISUPPORTS(ScreenOrientation::FullscreenEventListener,
+                  nsIDOMEventListener)
+
+NS_IMETHODIMP
+ScreenOrientation::FullscreenEventListener::HandleEvent(Event* aEvent) {
+#ifdef DEBUG
+  nsAutoString eventType;
+  aEvent->GetType(eventType);
+
+  MOZ_ASSERT(eventType.EqualsLiteral("fullscreenchange"));
+#endif
+
+  nsCOMPtr<EventTarget> target = aEvent->GetCurrentTarget();
+  MOZ_ASSERT(target);
+
+  nsCOMPtr<Document> doc = do_QueryInterface(target);
+  MOZ_ASSERT(doc);
+
+  // We have to make sure that the event we got is the event sent when
+  // fullscreen is disabled because we could get one when fullscreen
+  // got enabled if the lock call is done at the same moment.
+  if (doc->Fullscreen()) {
+    return NS_OK;
+  }
+
+  hal::UnlockScreenOrientation();
+
+  target->RemoveSystemEventListener(u"fullscreenchange"_ns, this, true);
+  return NS_OK;
+}