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diff --git a/dom/workers/remoteworkers/RemoteWorkerService.h b/dom/workers/remoteworkers/RemoteWorkerService.h
new file mode 100644
index 0000000000..9e05e3958b
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+++ b/dom/workers/remoteworkers/RemoteWorkerService.h
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+/* -*- 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_RemoteWorkerService_h
+#define mozilla_dom_RemoteWorkerService_h
+
+#include "mozilla/AlreadyAddRefed.h"
+#include "mozilla/DataMutex.h"
+#include "nsCOMPtr.h"
+#include "nsIObserver.h"
+#include "nsISupportsImpl.h"
+
+class nsIThread;
+
+namespace mozilla::dom {
+
+class RemoteWorkerService;
+class RemoteWorkerServiceChild;
+class RemoteWorkerServiceShutdownBlocker;
+
+/**
+ * Refcounted lifecycle helper; when its refcount goes to zero its destructor
+ * will call RemoteWorkerService::Shutdown() which will remove the shutdown
+ * blocker and shutdown the "Worker Launcher" thread.
+ *
+ * The RemoteWorkerService itself will hold a reference to this singleton which
+ * it will use to hand out additional refcounts to RemoteWorkerChild instances.
+ * When the shutdown blocker is notified that it's time to shutdown, the
+ * RemoteWorkerService's reference will be dropped.
+ */
+class RemoteWorkerServiceKeepAlive {
+ public:
+  explicit RemoteWorkerServiceKeepAlive(
+      RemoteWorkerServiceShutdownBlocker* aBlocker);
+
+ private:
+  ~RemoteWorkerServiceKeepAlive();
+
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(RemoteWorkerServiceKeepAlive);
+
+  RefPtr<RemoteWorkerServiceShutdownBlocker> mBlocker;
+};
+
+/**
+ * Every process has a RemoteWorkerService which does the actual spawning of
+ * RemoteWorkerChild instances. The RemoteWorkerService creates a "Worker
+ * Launcher" thread at initialization on which it creates a
+ * RemoteWorkerServiceChild to service spawn requests. The thread is exposed as
+ * RemoteWorkerService::Thread(). A new/distinct thread is used because we
+ * (eventually) don't want to deal with main-thread contention, content
+ * processes have no equivalent of a PBackground thread, and actors are bound to
+ * specific threads.
+ *
+ * (Disclaimer: currently most RemoteWorkerOps need to happen on the main thread
+ * because the main-thread ends up as the owner of the worker and all
+ * manipulation of the worker must happen from the owning thread.)
+ */
+class RemoteWorkerService final : public nsIObserver {
+  friend class RemoteWorkerServiceShutdownBlocker;
+  friend class RemoteWorkerServiceKeepAlive;
+
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+
+  // To be called when a process is initialized on main-thread.
+  static void Initialize();
+
+  static nsIThread* Thread();
+
+  // Called by RemoteWorkerChild instances on the "Worker Launcher" thread at
+  // their creation to assist in tracking when it's safe to shutdown the
+  // RemoteWorkerService and "Worker Launcher" thread.  This method will return
+  // a null pointer if the RemoteWorkerService has already begun shutdown.
+  //
+  // This is somewhat awkwardly a static method because the RemoteWorkerChild
+  // instances are not managed by RemoteWorkerServiceChild, but instead are
+  // managed by PBackground(Child).  So we either need to find the
+  // RemoteWorkerService via the hidden singleton or by having the
+  // RemoteWorkerChild use PBackgroundChild::ManagedPRemoteWorkerServiceChild()
+  // to locate the instance.  We are choosing to use the singleton because we
+  // already need to acquire a mutex in the call regardless and the upcoming
+  // refactorings may want to start using new toplevel protocols and this will
+  // avoid requiring a change when that happens.
+  static already_AddRefed<RemoteWorkerServiceKeepAlive> MaybeGetKeepAlive();
+
+ private:
+  RemoteWorkerService();
+  ~RemoteWorkerService();
+
+  nsresult InitializeOnMainThread();
+
+  void InitializeOnTargetThread();
+
+  void CloseActorOnTargetThread();
+
+  // Called by RemoteWorkerServiceShutdownBlocker when it's time to drop the
+  // RemoteWorkerServiceKeepAlive reference.
+  void BeginShutdown();
+
+  // Called by RemoteWorkerServiceShutdownBlocker when the blocker has been
+  // removed and it's safe to shutdown the "Worker Launcher" thread.
+  void FinishShutdown();
+
+  nsCOMPtr<nsIThread> mThread;
+  RefPtr<RemoteWorkerServiceChild> mActor;
+  // The keep-alive is set and cleared on the main thread but we will hand out
+  // additional references to it from the "Worker Launcher" thread, so it's
+  // appropriate to use a mutex.  (Alternately we could have used a ThreadBound
+  // and set and cleared on the "Worker Launcher" thread, but that would
+  // involve more moving parts and could have complicated edge cases.)
+  DataMutex<RefPtr<RemoteWorkerServiceKeepAlive>> mKeepAlive;
+  // In order to poll the blocker to know when we can stop spinning the event
+  // loop at shutdown, we retain a reference to the blocker.
+  RefPtr<RemoteWorkerServiceShutdownBlocker> mShutdownBlocker;
+};
+
+}  // namespace mozilla::dom
+
+#endif  // mozilla_dom_RemoteWorkerService_h