8 files changed, 884 insertions, 0 deletions
diff --git a/dom/system/windows/location/PWindowsLocation.ipdl b/dom/system/windows/location/PWindowsLocation.ipdl
new file mode 100644
index 0000000000..db53b5c805
--- /dev/null
+++ b/dom/system/windows/location/PWindowsLocation.ipdl
@@ -0,0 +1,38 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et ft=cpp : */
+/* 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 PWindowsUtils;
+
+[RefCounted] using class nsIDOMGeoPosition from "nsGeoPositionIPCSerialiser.h";
+
+namespace mozilla {
+namespace dom {
+
+// Proxies geolocation functions to a utility process so that we
+// can safely handle crashes in the ILocation API.  Messages to the child
+// are proxies for the ILocation COM object.  Messages to the parent
+// are proxied nsIGeolocationUpdate callbacks.
+protocol PWindowsLocation {
+    manager PWindowsUtils;
+
+child:
+  async Startup();
+  async RegisterForReport();
+  async UnregisterForReport();
+  async SetHighAccuracy(bool aEnable);
+
+  async __delete__();
+
+parent:
+  // Update geolocation with new position information.
+  async Update(nullable nsIDOMGeoPosition aPosition);
+
+  // The geolocation API has reported an error.
+  async Failed(uint16_t aError);
+};
+
+}  // namespace dom
+}  // namespace mozilla
diff --git a/dom/system/windows/location/WindowsLocationChild.cpp b/dom/system/windows/location/WindowsLocationChild.cpp
new file mode 100644
index 0000000000..514ae4610f
--- /dev/null
+++ b/dom/system/windows/location/WindowsLocationChild.cpp
@@ -0,0 +1,257 @@
+/* -*- 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 "WindowsLocationChild.h"
+#include "nsCOMPtr.h"
+#include "WindowsLocationProvider.h"
+#include "mozilla/dom/GeolocationPosition.h"
+#include "mozilla/dom/GeolocationPositionErrorBinding.h"
+#include "mozilla/Telemetry.h"
+#include "nsIGeolocationProvider.h"
+
+#include <locationapi.h>
+
+namespace mozilla::dom {
+
+extern LazyLogModule gWindowsLocationProviderLog;
+#define LOG(...) \
+  MOZ_LOG(gWindowsLocationProviderLog, LogLevel::Debug, (__VA_ARGS__))
+
+class LocationEvent final : public ILocationEvents {
+ public:
+  explicit LocationEvent(WindowsLocationChild* aActor)
+      : mActor(aActor), mRefCnt(0) {}
+
+  // IUnknown interface
+  STDMETHODIMP_(ULONG) AddRef() override;
+  STDMETHODIMP_(ULONG) Release() override;
+  STDMETHODIMP QueryInterface(REFIID iid, void** ppv) override;
+
+  // ILocationEvents interface
+  STDMETHODIMP OnStatusChanged(REFIID aReportType,
+                               LOCATION_REPORT_STATUS aStatus) override;
+  STDMETHODIMP OnLocationChanged(REFIID aReportType,
+                                 ILocationReport* aReport) override;
+
+ private:
+  // Making this a WeakPtr breaks the following cycle of strong references:
+  // WindowsLocationChild -> ILocation -> ILocationEvents (this)
+  //   -> WindowsLocationChild.
+  WeakPtr<WindowsLocationChild> mActor;
+
+  ULONG mRefCnt;
+};
+
+STDMETHODIMP_(ULONG)
+LocationEvent::AddRef() { return InterlockedIncrement(&mRefCnt); }
+
+STDMETHODIMP_(ULONG)
+LocationEvent::Release() {
+  ULONG count = InterlockedDecrement(&mRefCnt);
+  if (!count) {
+    delete this;
+    return 0;
+  }
+  return count;
+}
+
+STDMETHODIMP
+LocationEvent::QueryInterface(REFIID iid, void** ppv) {
+  if (!ppv) {
+    return E_INVALIDARG;
+  }
+
+  if (iid == IID_IUnknown) {
+    *ppv = static_cast<IUnknown*>(this);
+  } else if (iid == IID_ILocationEvents) {
+    *ppv = static_cast<ILocationEvents*>(this);
+  } else {
+    *ppv = nullptr;
+    return E_NOINTERFACE;
+  }
+
+  AddRef();
+  return S_OK;
+}
+
+STDMETHODIMP
+LocationEvent::OnStatusChanged(REFIID aReportType,
+                               LOCATION_REPORT_STATUS aStatus) {
+  LOG("LocationEvent::OnStatusChanged(%p, %p, %s, %04x)", this, mActor.get(),
+      aReportType == IID_ILatLongReport ? "true" : "false",
+      static_cast<uint32_t>(aStatus));
+
+  if (!mActor || aReportType != IID_ILatLongReport) {
+    return S_OK;
+  }
+
+  // When registering event, REPORT_INITIALIZING is fired at first.
+  // Then, when the location is found, REPORT_RUNNING is fired.
+  // We ignore those messages.
+  uint16_t err;
+  switch (aStatus) {
+    case REPORT_ACCESS_DENIED:
+      err = GeolocationPositionError_Binding::PERMISSION_DENIED;
+      break;
+    case REPORT_NOT_SUPPORTED:
+    case REPORT_ERROR:
+      err = GeolocationPositionError_Binding::POSITION_UNAVAILABLE;
+      break;
+    default:
+      return S_OK;
+  }
+
+  mActor->SendFailed(err);
+  return S_OK;
+}
+
+STDMETHODIMP
+LocationEvent::OnLocationChanged(REFIID aReportType, ILocationReport* aReport) {
+  LOG("LocationEvent::OnLocationChanged(%p, %p, %s)", this, mActor.get(),
+      aReportType == IID_ILatLongReport ? "true" : "false");
+
+  if (!mActor || aReportType != IID_ILatLongReport) {
+    return S_OK;
+  }
+
+  RefPtr<ILatLongReport> latLongReport;
+  if (FAILED(aReport->QueryInterface(IID_ILatLongReport,
+                                     getter_AddRefs(latLongReport)))) {
+    return E_FAIL;
+  }
+
+  DOUBLE latitude = 0.0;
+  latLongReport->GetLatitude(&latitude);
+
+  DOUBLE longitude = 0.0;
+  latLongReport->GetLongitude(&longitude);
+
+  DOUBLE alt = UnspecifiedNaN<double>();
+  latLongReport->GetAltitude(&alt);
+
+  DOUBLE herror = 0.0;
+  latLongReport->GetErrorRadius(&herror);
+
+  DOUBLE verror = UnspecifiedNaN<double>();
+  latLongReport->GetAltitudeError(&verror);
+
+  double heading = UnspecifiedNaN<double>();
+  double speed = UnspecifiedNaN<double>();
+
+  // nsGeoPositionCoords will convert NaNs to null for optional properties of
+  // the JavaScript Coordinates object.
+  RefPtr<nsGeoPosition> position =
+      new nsGeoPosition(latitude, longitude, alt, herror, verror, heading,
+                        speed, PR_Now() / PR_USEC_PER_MSEC);
+  mActor->SendUpdate(position);
+
+  return S_OK;
+}
+
+WindowsLocationChild::WindowsLocationChild() {
+  LOG("WindowsLocationChild::WindowsLocationChild(%p)", this);
+}
+
+WindowsLocationChild::~WindowsLocationChild() {
+  LOG("WindowsLocationChild::~WindowsLocationChild(%p)", this);
+}
+
+::mozilla::ipc::IPCResult WindowsLocationChild::RecvStartup() {
+  LOG("WindowsLocationChild::RecvStartup(%p, %p)", this, mLocation.get());
+  if (mLocation) {
+    return IPC_OK();
+  }
+
+  RefPtr<ILocation> location;
+  if (FAILED(::CoCreateInstance(CLSID_Location, nullptr, CLSCTX_INPROC_SERVER,
+                                IID_ILocation, getter_AddRefs(location)))) {
+    LOG("WindowsLocationChild(%p) failed to create ILocation", this);
+    // We will use MLS provider
+    SendFailed(GeolocationPositionError_Binding::POSITION_UNAVAILABLE);
+    return IPC_OK();
+  }
+
+  IID reportTypes[] = {IID_ILatLongReport};
+  if (FAILED(location->RequestPermissions(nullptr, reportTypes, 1, FALSE))) {
+    LOG("WindowsLocationChild(%p) failed to set ILocation permissions", this);
+    // We will use MLS provider
+    SendFailed(GeolocationPositionError_Binding::POSITION_UNAVAILABLE);
+    return IPC_OK();
+  }
+
+  mLocation = location;
+  return IPC_OK();
+}
+
+::mozilla::ipc::IPCResult WindowsLocationChild::RecvSetHighAccuracy(
+    bool aEnable) {
+  LOG("WindowsLocationChild::RecvSetHighAccuracy(%p, %p, %s)", this,
+      mLocation.get(), aEnable ? "true" : "false");
+
+  // We sometimes call SetHighAccuracy before Startup, so we save the
+  // request and set it later, in RegisterForReport.
+  mHighAccuracy = aEnable;
+
+  return IPC_OK();
+}
+
+::mozilla::ipc::IPCResult WindowsLocationChild::RecvRegisterForReport() {
+  LOG("WindowsLocationChild::RecvRegisterForReport(%p, %p)", this,
+      mLocation.get());
+
+  if (!mLocation) {
+    SendFailed(GeolocationPositionError_Binding::POSITION_UNAVAILABLE);
+    return IPC_OK();
+  }
+
+  LOCATION_DESIRED_ACCURACY desiredAccuracy;
+  if (mHighAccuracy) {
+    desiredAccuracy = LOCATION_DESIRED_ACCURACY_HIGH;
+  } else {
+    desiredAccuracy = LOCATION_DESIRED_ACCURACY_DEFAULT;
+  }
+
+  if (NS_WARN_IF(FAILED(mLocation->SetDesiredAccuracy(IID_ILatLongReport,
+                                                      desiredAccuracy)))) {
+    SendFailed(GeolocationPositionError_Binding::POSITION_UNAVAILABLE);
+    return IPC_OK();
+  }
+
+  auto event = MakeRefPtr<LocationEvent>(this);
+  if (NS_WARN_IF(
+          FAILED(mLocation->RegisterForReport(event, IID_ILatLongReport, 0)))) {
+    SendFailed(GeolocationPositionError_Binding::POSITION_UNAVAILABLE);
+  }
+
+  LOG("WindowsLocationChild::RecvRegisterForReport successfully registered");
+  return IPC_OK();
+}
+
+::mozilla::ipc::IPCResult WindowsLocationChild::RecvUnregisterForReport() {
+  LOG("WindowsLocationChild::RecvUnregisterForReport(%p, %p)", this,
+      mLocation.get());
+
+  if (!mLocation) {
+    return IPC_OK();
+  }
+
+  // This will free the LocationEvent we created in RecvRegisterForReport.
+  Unused << NS_WARN_IF(
+      FAILED(mLocation->UnregisterForReport(IID_ILatLongReport)));
+
+  // The ILocation object is not reusable.  Unregistering, restarting and
+  // re-registering for reports does not work;  the callback is never
+  // called in that case.  For that reason, we re-create the ILocation
+  // object with a call to Startup after unregistering if we need it again.
+  mLocation = nullptr;
+  return IPC_OK();
+}
+
+void WindowsLocationChild::ActorDestroy(ActorDestroyReason aWhy) {
+  LOG("WindowsLocationChild::ActorDestroy(%p, %p)", this, mLocation.get());
+  mLocation = nullptr;
+}
+
+}  // namespace mozilla::dom
diff --git a/dom/system/windows/location/WindowsLocationChild.h b/dom/system/windows/location/WindowsLocationChild.h
new file mode 100644
index 0000000000..ac51cff213
--- /dev/null
+++ b/dom/system/windows/location/WindowsLocationChild.h
@@ -0,0 +1,44 @@
+/* -*- 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_WindowsLocationChild_h__
+#define mozilla_dom_WindowsLocationChild_h__
+
+#include "mozilla/dom/PWindowsLocationChild.h"
+#include "mozilla/WeakPtr.h"
+
+class ILocation;
+
+namespace mozilla::dom {
+
+// Geolocation actor in utility process.
+class WindowsLocationChild final : public PWindowsLocationChild,
+                                   public SupportsWeakPtr {
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(WindowsLocationChild, override);
+
+ public:
+  WindowsLocationChild();
+
+  using IPCResult = ::mozilla::ipc::IPCResult;
+
+  IPCResult RecvStartup();
+  IPCResult RecvRegisterForReport();
+  IPCResult RecvUnregisterForReport();
+  IPCResult RecvSetHighAccuracy(bool aEnable);
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+
+ private:
+  ~WindowsLocationChild() override;
+
+  // The COM object the actors are proxying calls for.
+  RefPtr<ILocation> mLocation;
+
+  bool mHighAccuracy = false;
+};
+
+}  // namespace mozilla::dom
+
+#endif  // mozilla_dom_WindowsLocationChild_h__
diff --git a/dom/system/windows/location/WindowsLocationParent.cpp b/dom/system/windows/location/WindowsLocationParent.cpp
new file mode 100644
index 0000000000..f19bcb8b0d
--- /dev/null
+++ b/dom/system/windows/location/WindowsLocationParent.cpp
@@ -0,0 +1,36 @@
+/* -*- 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 "WindowsLocationParent.h"
+#include "nsIDOMGeoPosition.h"
+#include "WindowsLocationProvider.h"
+
+namespace mozilla::dom {
+
+::mozilla::ipc::IPCResult WindowsLocationParent::RecvUpdate(
+    RefPtr<nsIDOMGeoPosition> aGeoPosition) {
+  if (mProvider) {
+    mProvider->RecvUpdate(aGeoPosition);
+  }
+  return IPC_OK();
+}
+
+// A failure occurred.  This may be translated into a
+// nsIGeolocationUpdate::NotifyError or may be ignored if the MLS fallback
+// is available.
+::mozilla::ipc::IPCResult WindowsLocationParent::RecvFailed(uint16_t err) {
+  if (mProvider) {
+    mProvider->RecvFailed(err);
+  }
+  return IPC_OK();
+}
+
+void WindowsLocationParent::ActorDestroy(ActorDestroyReason aReason) {
+  if (mProvider) {
+    mProvider->ActorStopped();
+  }
+}
+
+}  // namespace mozilla::dom
diff --git a/dom/system/windows/location/WindowsLocationParent.h b/dom/system/windows/location/WindowsLocationParent.h
new file mode 100644
index 0000000000..01538246ea
--- /dev/null
+++ b/dom/system/windows/location/WindowsLocationParent.h
@@ -0,0 +1,52 @@
+/* -*- 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_WindowsLocationParent_h__
+#define mozilla_dom_WindowsLocationParent_h__
+
+#include "nsCOMPtr.h"
+#include "mozilla/dom/PWindowsLocationParent.h"
+
+class nsGeoPosition;
+class nsIGeolocationUpdate;
+
+namespace mozilla::dom {
+
+class WindowsLocationProvider;
+
+// Geolocation actor in main process.
+// This may receive messages asynchronously, even after it sends Unregister
+// to the child.
+class WindowsLocationParent final : public PWindowsLocationParent {
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(WindowsLocationParent, override);
+
+  using IPCResult = ::mozilla::ipc::IPCResult;
+
+  explicit WindowsLocationParent(WindowsLocationProvider* aProvider)
+      : mProvider(aProvider) {}
+
+  // Update geolocation with new position information.
+  IPCResult RecvUpdate(RefPtr<nsIDOMGeoPosition> aGeoPosition);
+
+  // A failure occurred.  This may be translated into a
+  // nsIGeolocationUpdate::NotifyError or may be ignored if the MLS fallback
+  // is available.
+  IPCResult RecvFailed(uint16_t err);
+
+  void ActorDestroy(ActorDestroyReason aReason) override;
+
+  // After this, the actor will simply ignore any incoming messages.
+  void DetachFromLocationProvider() { mProvider = nullptr; }
+
+ private:
+  ~WindowsLocationParent() override = default;
+
+  WindowsLocationProvider* mProvider;
+};
+
+}  // namespace mozilla::dom
+
+#endif  // mozilla_dom_WindowsLocationParent_h__
diff --git a/dom/system/windows/location/WindowsLocationProvider.cpp b/dom/system/windows/location/WindowsLocationProvider.cpp
new file mode 100644
index 0000000000..92a6f2c9cc
--- /dev/null
+++ b/dom/system/windows/location/WindowsLocationProvider.cpp
@@ -0,0 +1,350 @@
+/* -*- 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 "WindowsLocationProvider.h"
+#include "WindowsLocationParent.h"
+#include "mozilla/dom/WindowsUtilsParent.h"
+#include "GeolocationPosition.h"
+#include "nsComponentManagerUtils.h"
+#include "mozilla/ipc/UtilityProcessManager.h"
+#include "mozilla/ipc/UtilityProcessSandboxing.h"
+#include "prtime.h"
+#include "MLSFallback.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Logging.h"
+#include "mozilla/FloatingPoint.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/dom/GeolocationPositionErrorBinding.h"
+
+namespace mozilla::dom {
+
+LazyLogModule gWindowsLocationProviderLog("WindowsLocationProvider");
+#define LOG(...) \
+  MOZ_LOG(gWindowsLocationProviderLog, LogLevel::Debug, (__VA_ARGS__))
+
+class MLSUpdate : public nsIGeolocationUpdate {
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIGEOLOCATIONUPDATE
+  explicit MLSUpdate(nsIGeolocationUpdate* aCallback) : mCallback(aCallback) {}
+
+ private:
+  nsCOMPtr<nsIGeolocationUpdate> mCallback;
+  virtual ~MLSUpdate() {}
+};
+
+NS_IMPL_ISUPPORTS(MLSUpdate, nsIGeolocationUpdate);
+
+NS_IMETHODIMP
+MLSUpdate::Update(nsIDOMGeoPosition* aPosition) {
+  if (!mCallback) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsCOMPtr<nsIDOMGeoPositionCoords> coords;
+  aPosition->GetCoords(getter_AddRefs(coords));
+  if (!coords) {
+    return NS_ERROR_FAILURE;
+  }
+  Telemetry::Accumulate(Telemetry::GEOLOCATION_WIN8_SOURCE_IS_MLS, true);
+  return mCallback->Update(aPosition);
+}
+NS_IMETHODIMP
+MLSUpdate::NotifyError(uint16_t aError) {
+  if (!mCallback) {
+    return NS_ERROR_FAILURE;
+  }
+  nsCOMPtr<nsIGeolocationUpdate> callback(mCallback);
+  return callback->NotifyError(aError);
+}
+
+NS_IMPL_ISUPPORTS(WindowsLocationProvider, nsIGeolocationProvider)
+
+WindowsLocationProvider::WindowsLocationProvider() {
+  LOG("WindowsLocationProvider::WindowsLocationProvider(%p)", this);
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MaybeCreateLocationActor();
+}
+
+WindowsLocationProvider::~WindowsLocationProvider() {
+  LOG("WindowsLocationProvider::~WindowsLocationProvider(%p,%p,%p)", this,
+      mActor.get(), mActorPromise.get());
+  Send__delete__();
+  ReleaseUtilityProcess();
+  CancelMLSProvider();
+}
+
+void WindowsLocationProvider::MaybeCreateLocationActor() {
+  LOG("WindowsLocationProvider::MaybeCreateLocationActor(%p)", this);
+  if (mActor || mActorPromise) {
+    return;
+  }
+
+  auto utilityProc = mozilla::ipc::UtilityProcessManager::GetSingleton();
+  MOZ_ASSERT(utilityProc);
+
+  // Create a PWindowsLocation actor in the Windows utility process.
+  // This will attempt to launch the process if it doesn't already exist.
+  RefPtr<WindowsLocationProvider> self = this;
+  auto wuPromise = utilityProc->GetWindowsUtilsPromise();
+  mActorPromise = wuPromise->Then(
+      GetCurrentSerialEventTarget(), __func__,
+      [self](RefPtr<WindowsUtilsParent> wup) {
+        self->mActorPromise = nullptr;
+        auto actor = MakeRefPtr<WindowsLocationParent>(self);
+        if (!wup->SendPWindowsLocationConstructor(actor)) {
+          LOG("WindowsLocationProvider(%p) SendPWindowsLocationConstructor "
+              "failed",
+              self.get());
+          actor->DetachFromLocationProvider();
+          self->mActor = nullptr;
+          return WindowsLocationPromise::CreateAndReject(false, __func__);
+        }
+        LOG("WindowsLocationProvider connected to actor (%p,%p,%p)", self.get(),
+            self->mActor.get(), self->mActorPromise.get());
+        self->mActor = actor;
+        return WindowsLocationPromise::CreateAndResolve(self->mActor, __func__);
+      },
+
+      [self](nsresult aError) {
+        LOG("WindowsLocationProvider failed to connect to actor (%p,%p,%p)",
+            self.get(), self->mActor.get(), self->mActorPromise.get());
+        self->mActorPromise = nullptr;
+        return WindowsLocationPromise::CreateAndReject(false, __func__);
+      });
+
+  if (mActor) {
+    // Utility process already existed and mActorPromise was resolved
+    // immediately.
+    mActorPromise = nullptr;
+  }
+}
+
+void WindowsLocationProvider::ReleaseUtilityProcess() {
+  LOG("WindowsLocationProvider::ReleaseUtilityProcess(%p)", this);
+  auto utilityProc = mozilla::ipc::UtilityProcessManager::GetIfExists();
+  if (utilityProc) {
+    utilityProc->ReleaseWindowsUtils();
+  }
+}
+
+template <typename Fn>
+bool WindowsLocationProvider::WhenActorIsReady(Fn&& fn) {
+  if (mActor) {
+    return fn(mActor);
+  }
+
+  if (mActorPromise) {
+    mActorPromise->Then(
+        GetCurrentSerialEventTarget(), __func__,
+        [fn](const RefPtr<WindowsLocationParent>& actor) {
+          Unused << fn(actor.get());
+          return actor;
+        },
+        [](bool) { return false; });
+    return true;
+  }
+
+  // The remote process failed to start.
+  return false;
+}
+
+bool WindowsLocationProvider::SendStartup() {
+  LOG("WindowsLocationProvider::SendStartup(%p)", this);
+  MaybeCreateLocationActor();
+  return WhenActorIsReady(
+      [](WindowsLocationParent* actor) { return actor->SendStartup(); });
+}
+
+bool WindowsLocationProvider::SendRegisterForReport(
+    nsIGeolocationUpdate* aCallback) {
+  LOG("WindowsLocationProvider::SendRegisterForReport(%p)", this);
+  RefPtr<WindowsLocationProvider> self = this;
+  RefPtr<nsIGeolocationUpdate> cb = aCallback;
+  return WhenActorIsReady([self, cb](WindowsLocationParent* actor) {
+    MOZ_ASSERT(!self->mCallback);
+    if (actor->SendRegisterForReport()) {
+      self->mCallback = cb;
+      return true;
+    }
+    return false;
+  });
+}
+
+bool WindowsLocationProvider::SendUnregisterForReport() {
+  LOG("WindowsLocationProvider::SendUnregisterForReport(%p)", this);
+  RefPtr<WindowsLocationProvider> self = this;
+  return WhenActorIsReady([self](WindowsLocationParent* actor) {
+    self->mCallback = nullptr;
+    if (actor->SendUnregisterForReport()) {
+      return true;
+    }
+    return false;
+  });
+}
+
+bool WindowsLocationProvider::SendSetHighAccuracy(bool aEnable) {
+  LOG("WindowsLocationProvider::SendSetHighAccuracy(%p)", this);
+  return WhenActorIsReady([aEnable](WindowsLocationParent* actor) {
+    return actor->SendSetHighAccuracy(aEnable);
+  });
+}
+
+bool WindowsLocationProvider::Send__delete__() {
+  LOG("WindowsLocationProvider::Send__delete__(%p)", this);
+  return WhenActorIsReady([self = RefPtr{this}](WindowsLocationParent*) {
+    if (WindowsLocationParent::Send__delete__(self->mActor)) {
+      if (self->mActor) {
+        self->mActor->DetachFromLocationProvider();
+        self->mActor = nullptr;
+      }
+      return true;
+    }
+    return false;
+  });
+}
+
+void WindowsLocationProvider::RecvUpdate(
+    RefPtr<nsIDOMGeoPosition> aGeoPosition) {
+  LOG("WindowsLocationProvider::RecvUpdate(%p)", this);
+  if (!mCallback) {
+    return;
+  }
+
+  mCallback->Update(aGeoPosition.get());
+
+  Telemetry::Accumulate(Telemetry::GEOLOCATION_WIN8_SOURCE_IS_MLS, false);
+}
+
+void WindowsLocationProvider::RecvFailed(uint16_t err) {
+  LOG("WindowsLocationProvider::RecvFailed(%p)", this);
+  // Cannot get current location at this time.  We use MLS instead.
+  if (mMLSProvider || !mCallback) {
+    return;
+  }
+
+  if (NS_SUCCEEDED(CreateAndWatchMLSProvider(mCallback))) {
+    return;
+  }
+
+  // No ILocation and no MLS, so we have failed completely.
+  // We keep strong references to objects that we need to guarantee
+  // will live past the NotifyError callback.
+  RefPtr<WindowsLocationProvider> self = this;
+  nsCOMPtr<nsIGeolocationUpdate> callback = mCallback;
+  callback->NotifyError(err);
+}
+
+void WindowsLocationProvider::ActorStopped() {
+  // ActorDestroy has run.  Make sure UtilityProcessHost no longer tries to use
+  // it.
+  ReleaseUtilityProcess();
+
+  if (mWatching) {
+    // Treat as remote geolocation error, which will cause it to fallback
+    // to MLS if it hasn't already.
+    mWatching = false;
+    RecvFailed(GeolocationPositionError_Binding::POSITION_UNAVAILABLE);
+    return;
+  }
+
+  MOZ_ASSERT(!mActorPromise);
+  if (mActor) {
+    mActor->DetachFromLocationProvider();
+    mActor = nullptr;
+  }
+}
+
+NS_IMETHODIMP
+WindowsLocationProvider::Startup() {
+  LOG("WindowsLocationProvider::Startup(%p, %p, %p)", this, mActor.get(),
+      mActorPromise.get());
+  // If this fails, we will use the MLS fallback.
+  SendStartup();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WindowsLocationProvider::Watch(nsIGeolocationUpdate* aCallback) {
+  LOG("WindowsLocationProvider::Watch(%p, %p, %p, %p, %d)", this, mActor.get(),
+      mActorPromise.get(), aCallback, mWatching);
+  if (mWatching) {
+    return NS_OK;
+  }
+
+  if (SendRegisterForReport(aCallback)) {
+    mWatching = true;
+    return NS_OK;
+  }
+
+  // Couldn't send request.  We will use MLS instead.
+  return CreateAndWatchMLSProvider(aCallback);
+}
+
+NS_IMETHODIMP
+WindowsLocationProvider::Shutdown() {
+  LOG("WindowsLocationProvider::Shutdown(%p, %p, %p)", this, mActor.get(),
+      mActorPromise.get());
+
+  if (mWatching) {
+    SendUnregisterForReport();
+    mWatching = false;
+  }
+
+  CancelMLSProvider();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+WindowsLocationProvider::SetHighAccuracy(bool enable) {
+  LOG("WindowsLocationProvider::SetHighAccuracy(%p, %p, %p, %s)", this,
+      mActor.get(), mActorPromise.get(), enable ? "true" : "false");
+  if (mMLSProvider) {
+    // Ignored when running MLS fallback.
+    return NS_OK;
+  }
+
+  if (!SendSetHighAccuracy(enable)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // Since we SendSetHighAccuracy asynchronously, we cannot say for sure
+  // that it will succeed.  If it does fail then we will get a
+  // RecvFailed IPC message, which will cause a fallback to MLS.
+  return NS_OK;
+}
+
+nsresult WindowsLocationProvider::CreateAndWatchMLSProvider(
+    nsIGeolocationUpdate* aCallback) {
+  LOG("WindowsLocationProvider::CreateAndWatchMLSProvider"
+      "(%p, %p, %p, %p, %p)",
+      this, mMLSProvider.get(), mActor.get(), mActorPromise.get(), aCallback);
+
+  if (mMLSProvider) {
+    return NS_OK;
+  }
+
+  mMLSProvider = new MLSFallback(0);
+  return mMLSProvider->Startup(new MLSUpdate(aCallback));
+}
+
+void WindowsLocationProvider::CancelMLSProvider() {
+  LOG("WindowsLocationProvider::CancelMLSProvider"
+      "(%p, %p, %p, %p, %p)",
+      this, mMLSProvider.get(), mActor.get(), mActorPromise.get(),
+      mCallback.get());
+
+  if (!mMLSProvider) {
+    return;
+  }
+
+  mMLSProvider->Shutdown();
+  mMLSProvider = nullptr;
+}
+
+#undef LOG
+
+}  // namespace mozilla::dom
diff --git a/dom/system/windows/location/WindowsLocationProvider.h b/dom/system/windows/location/WindowsLocationProvider.h
new file mode 100644
index 0000000000..d1e4dfa936
--- /dev/null
+++ b/dom/system/windows/location/WindowsLocationProvider.h
@@ -0,0 +1,78 @@
+/* -*- 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_WindowsLocationProvider_h__
+#define mozilla_dom_WindowsLocationProvider_h__
+
+#include "nsCOMPtr.h"
+#include "nsIGeolocationProvider.h"
+#include "mozilla/MozPromise.h"
+
+class MLSFallback;
+
+namespace mozilla::dom {
+
+class WindowsLocationParent;
+
+// Uses a PWindowsLocation actor to subscribe to geolocation updates from the
+// Windows utility process and falls back to MLS when it is not available or
+// fails.
+class WindowsLocationProvider final : public nsIGeolocationProvider {
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIGEOLOCATIONPROVIDER
+
+  WindowsLocationProvider();
+
+ private:
+  friend WindowsLocationParent;
+
+  ~WindowsLocationProvider();
+
+  nsresult CreateAndWatchMLSProvider(nsIGeolocationUpdate* aCallback);
+  void CancelMLSProvider();
+
+  void MaybeCreateLocationActor();
+  void ReleaseUtilityProcess();
+
+  // These methods either send the message on the existing actor or queue
+  // the messages to be sent (in order) once the actor exists.
+  bool SendStartup();
+  bool SendRegisterForReport(nsIGeolocationUpdate* aCallback);
+  bool SendUnregisterForReport();
+  bool SendSetHighAccuracy(bool aEnable);
+  bool Send__delete__();
+
+  void RecvUpdate(RefPtr<nsIDOMGeoPosition> aGeoPosition);
+  // See bug 1539864 for MOZ_CAN_RUN_SCRIPT_BOUNDARY justification.
+  MOZ_CAN_RUN_SCRIPT_BOUNDARY void RecvFailed(uint16_t err);
+
+  // The utility process actor has ended its connection, either successfully
+  // or with an error.
+  void ActorStopped();
+
+  // Run fn once actor is ready to send messages, which may be immediately.
+  template <typename Fn>
+  bool WhenActorIsReady(Fn&& fn);
+
+  RefPtr<MLSFallback> mMLSProvider;
+
+  nsCOMPtr<nsIGeolocationUpdate> mCallback;
+
+  using WindowsLocationPromise =
+      MozPromise<RefPtr<WindowsLocationParent>, bool, false>;
+
+  // Before the utility process exists, we have a promise that we will get our
+  // location actor.  mActor and mActorPromise are never both set.
+  RefPtr<WindowsLocationPromise> mActorPromise;
+  RefPtr<WindowsLocationParent> mActor;
+
+  bool mWatching = false;
+};
+
+}  // namespace mozilla::dom
+
+#endif  // mozilla_dom_WindowsLocationProvider_h__
diff --git a/dom/system/windows/location/moz.build b/dom/system/windows/location/moz.build
new file mode 100644
index 0000000000..8fafb99fb1
--- /dev/null
+++ b/dom/system/windows/location/moz.build
@@ -0,0 +1,29 @@
+# -*- 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/.
+
+EXPORTS.mozilla.dom += [
+    "WindowsLocationChild.h",
+    "WindowsLocationParent.h",
+]
+
+UNIFIED_SOURCES += [
+    "WindowsLocationParent.cpp",
+    "WindowsLocationProvider.cpp",
+]
+
+SOURCES += [
+    "WindowsLocationChild.cpp",  # includes locationapi.h
+]
+
+IPDL_SOURCES += [
+    "PWindowsLocation.ipdl",
+]
+
+LOCAL_INCLUDES += ["/dom/geolocation"]
+
+include("/ipc/chromium/chromium-config.mozbuild")
+
+FINAL_LIBRARY = "xul"