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diff --git a/dom/workers/remoteworkers/RemoteWorkerChild.h b/dom/workers/remoteworkers/RemoteWorkerChild.h
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+++ b/dom/workers/remoteworkers/RemoteWorkerChild.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_RemoteWorkerChild_h
+#define mozilla_dom_RemoteWorkerChild_h
+
+#include "nsCOMPtr.h"
+#include "nsISupportsImpl.h"
+#include "nsTArray.h"
+
+#include "mozilla/DataMutex.h"
+#include "mozilla/MozPromise.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/ThreadBound.h"
+#include "mozilla/dom/PRemoteWorkerChild.h"
+#include "mozilla/dom/ServiceWorkerOpArgs.h"
+
+class nsISerialEventTarget;
+class nsIConsoleReportCollector;
+
+namespace mozilla::dom {
+
+class ErrorValue;
+class FetchEventOpProxyChild;
+class RemoteWorkerData;
+class RemoteWorkerServiceKeepAlive;
+class ServiceWorkerOp;
+class UniqueMessagePortId;
+class WeakWorkerRef;
+class WorkerErrorReport;
+class WorkerPrivate;
+
+/**
+ * Background-managed "Worker Launcher"-thread-resident created via the
+ * RemoteWorkerManager to actually spawn the worker. Currently, the worker will
+ * be spawned from the main thread due to nsIPrincipal not being able to be
+ * created on background threads and other ownership invariants, most of which
+ * can be relaxed in the future.
+ */
+class RemoteWorkerChild final : public PRemoteWorkerChild {
+  friend class FetchEventOpProxyChild;
+  friend class PRemoteWorkerChild;
+  friend class ServiceWorkerOp;
+
+  ~RemoteWorkerChild();
+
+ public:
+  // Note that all IPC-using methods must only be invoked on the
+  // RemoteWorkerService thread which the inherited
+  // IProtocol::GetActorEventTarget() will return for us.
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(RemoteWorkerChild, final)
+
+  explicit RemoteWorkerChild(const RemoteWorkerData& aData);
+
+  void ExecWorker(const RemoteWorkerData& aData);
+
+  void ErrorPropagationOnMainThread(const WorkerErrorReport* aReport,
+                                    bool aIsErrorEvent);
+
+  void NotifyLock(bool aCreated);
+
+  void NotifyWebTransport(bool aCreated);
+
+  void FlushReportsOnMainThread(nsIConsoleReportCollector* aReporter);
+
+  void AddPortIdentifier(JSContext* aCx, WorkerPrivate* aWorkerPrivate,
+                         UniqueMessagePortId& aPortIdentifier);
+
+  RefPtr<GenericNonExclusivePromise> GetTerminationPromise();
+
+  RefPtr<GenericPromise> MaybeSendSetServiceWorkerSkipWaitingFlag();
+
+  const nsTArray<uint64_t>& WindowIDs() const { return mWindowIDs; }
+
+ private:
+  class InitializeWorkerRunnable;
+
+  class Op;
+  class SharedWorkerOp;
+
+  struct WorkerPrivateAccessibleState {
+    ~WorkerPrivateAccessibleState();
+    RefPtr<WorkerPrivate> mWorkerPrivate;
+  };
+
+  // Initial state, mWorkerPrivate is initially null but will be initialized on
+  // the main thread by ExecWorkerOnMainThread when the WorkerPrivate is
+  // created.  The state will transition to Running or Canceled, also from the
+  // main thread.
+  struct Pending : WorkerPrivateAccessibleState {
+    nsTArray<RefPtr<Op>> mPendingOps;
+  };
+
+  // Running, with the state transition happening on the main thread as a result
+  // of the worker successfully processing our initialization runnable,
+  // indicating that top-level script execution successfully completed.  Because
+  // all of our state transitions happen on the main thread and are posed in
+  // terms of the main thread's perspective of the worker's state, it's very
+  // possible for us to skip directly from Pending to Canceled because we decide
+  // to cancel/terminate the worker prior to it finishing script loading or
+  // reporting back to us.
+  struct Running : WorkerPrivateAccessibleState {};
+
+  // Cancel() has been called on the WorkerPrivate on the main thread by a
+  // TerminationOp, top-level script evaluation has failed and canceled the
+  // worker, or in the case of a SharedWorker, close() has been called on
+  // the global scope by content code and the worker has advanced to the
+  // Canceling state.  (Dedicated Workers can also self close, but they will
+  // never be RemoteWorkers.  Although a SharedWorker can own DedicatedWorkers.)
+  // Browser shutdown will result in a TerminationOp thanks to use of a shutdown
+  // blocker in the parent, so the RuntimeService shouldn't get involved, but we
+  // would also handle that case acceptably too.
+  //
+  // Because worker self-closing is still handled by dispatching a runnable to
+  // the main thread to effectively call WorkerPrivate::Cancel(), there isn't
+  // a race between a worker deciding to self-close and our termination ops.
+  //
+  // In this state, we have dropped the reference to the WorkerPrivate and will
+  // no longer be dispatching runnables to the worker.  We wait in this state
+  // until the termination lambda is invoked letting us know that the worker has
+  // entirely shutdown and we can advanced to the Killed state.
+  struct Canceled {};
+
+  // The worker termination lambda has been invoked and we know the Worker is
+  // entirely shutdown.  (Inherently it is possible for us to advance to this
+  // state while the nsThread for the worker is still in the process of
+  // shutting down, but no more worker code will run on it.)
+  //
+  // This name is chosen to match the Worker's own state model.
+  struct Killed {};
+
+  using State = Variant<Pending, Running, Canceled, Killed>;
+
+  // The state of the WorkerPrivate as perceived by the owner on the main
+  // thread.  All state transitions now happen on the main thread, but the
+  // Worker Launcher thread will consult the state and will directly append ops
+  // to the Pending queue
+  DataMutex<State> mState;
+
+  const RefPtr<RemoteWorkerServiceKeepAlive> mServiceKeepAlive;
+
+  class Op {
+   public:
+    NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING
+
+    virtual ~Op() = default;
+
+    virtual bool MaybeStart(RemoteWorkerChild* aOwner, State& aState) = 0;
+
+    virtual void StartOnMainThread(RefPtr<RemoteWorkerChild>& aOwner) = 0;
+
+    virtual void Cancel() = 0;
+  };
+
+  void ActorDestroy(ActorDestroyReason) override;
+
+  mozilla::ipc::IPCResult RecvExecOp(RemoteWorkerOp&& aOp);
+
+  mozilla::ipc::IPCResult RecvExecServiceWorkerOp(
+      ServiceWorkerOpArgs&& aArgs, ExecServiceWorkerOpResolver&& aResolve);
+
+  already_AddRefed<PFetchEventOpProxyChild> AllocPFetchEventOpProxyChild(
+      const ParentToChildServiceWorkerFetchEventOpArgs& aArgs);
+
+  mozilla::ipc::IPCResult RecvPFetchEventOpProxyConstructor(
+      PFetchEventOpProxyChild* aActor,
+      const ParentToChildServiceWorkerFetchEventOpArgs& aArgs) override;
+
+  nsresult ExecWorkerOnMainThread(RemoteWorkerData&& aData);
+
+  void ExceptionalErrorTransitionDuringExecWorker();
+
+  void RequestWorkerCancellation();
+
+  void InitializeOnWorker();
+
+  void CreationSucceededOnAnyThread();
+
+  void CreationFailedOnAnyThread();
+
+  void CreationSucceededOrFailedOnAnyThread(bool aDidCreationSucceed);
+
+  // Cancels the worker if it has been started and ensures that we transition
+  // to the Terminated state once the worker has been terminated or we have
+  // ensured that it will never start.
+  void CloseWorkerOnMainThread();
+
+  void ErrorPropagation(const ErrorValue& aValue);
+
+  void ErrorPropagationDispatch(nsresult aError);
+
+  // When the WorkerPrivate Cancellation lambda is invoked, it's possible that
+  // we have not yet advanced to running from pending, so we could be in either
+  // state.  This method is expected to be called by the Workers' cancellation
+  // lambda and will obtain the lock and call the
+  // TransitionStateFromPendingToCanceled if appropriate.  Otherwise it will
+  // directly move from the running state to the canceled state which does not
+  // require additional cleanup.
+  void OnWorkerCancellationTransitionStateFromPendingOrRunningToCanceled();
+  // A helper used by the above method by the worker cancellation lambda if the
+  // the worker hasn't started running, or in exceptional cases where we bail
+  // out of the ExecWorker method early.  The caller must be holding the lock
+  // (in order to pass in the state).
+  void TransitionStateFromPendingToCanceled(State& aState);
+  void TransitionStateFromCanceledToKilled();
+
+  void TransitionStateToRunning();
+
+  void TransitionStateToTerminated();
+
+  void TransitionStateToTerminated(State& aState);
+
+  void CancelAllPendingOps(State& aState);
+
+  void MaybeStartOp(RefPtr<Op>&& aOp);
+
+  const bool mIsServiceWorker;
+
+  // Touched on main-thread only.
+  nsTArray<uint64_t> mWindowIDs;
+
+  struct LauncherBoundData {
+    MozPromiseHolder<GenericNonExclusivePromise> mTerminationPromise;
+    // Flag to ensure we report creation at most once.  This could be cleaned up
+    // further.
+    bool mDidSendCreated = false;
+  };
+
+  ThreadBound<LauncherBoundData> mLauncherData;
+};
+
+}  // namespace mozilla::dom
+
+#endif  // mozilla_dom_RemoteWorkerChild_h