Adding upstream version 86.0.1.upstream/86.0.1upstream

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

1 files changed, 1968 insertions, 0 deletions

diff --git a/xpcom/threads/nsThreadUtils.h b/xpcom/threads/nsThreadUtils.h
new file mode 100644
index 0000000000..a8d64de83e
--- /dev/null
+++ b/xpcom/threads/nsThreadUtils.h
@@ -0,0 +1,1968 @@
+/* -*- 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 nsThreadUtils_h__
+#define nsThreadUtils_h__
+
+#include <type_traits>
+#include <utility>
+
+#include "MainThreadUtils.h"
+#include "mozilla/EventQueue.h"
+#include "mozilla/AbstractThread.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/Likely.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/ThreadLocal.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/Tuple.h"
+#include "nsCOMPtr.h"
+#include "nsICancelableRunnable.h"
+#include "nsIDiscardableRunnable.h"
+#include "nsIIdlePeriod.h"
+#include "nsIIdleRunnable.h"
+#include "nsINamed.h"
+#include "nsIRunnable.h"
+#include "nsIThreadManager.h"
+#include "nsITimer.h"
+#include "nsString.h"
+#include "prinrval.h"
+#include "prthread.h"
+
+class MessageLoop;
+class nsIThread;
+
+//-----------------------------------------------------------------------------
+// These methods are alternatives to the methods on nsIThreadManager, provided
+// for convenience.
+
+/**
+ * Create a new thread, and optionally provide an initial event for the thread.
+ *
+ * @param aName
+ *   The name of the thread.
+ * @param aResult
+ *   The resulting nsIThread object.
+ * @param aInitialEvent
+ *   The initial event to run on this thread.  This parameter may be null.
+ * @param aStackSize
+ *   The size in bytes to reserve for the thread's stack.
+ *
+ * @returns NS_ERROR_INVALID_ARG
+ *   Indicates that the given name is not unique.
+ */
+
+extern nsresult NS_NewNamedThread(
+    const nsACString& aName, nsIThread** aResult,
+    nsIRunnable* aInitialEvent = nullptr,
+    uint32_t aStackSize = nsIThreadManager::DEFAULT_STACK_SIZE);
+
+extern nsresult NS_NewNamedThread(
+    const nsACString& aName, nsIThread** aResult,
+    already_AddRefed<nsIRunnable> aInitialEvent,
+    uint32_t aStackSize = nsIThreadManager::DEFAULT_STACK_SIZE);
+
+template <size_t LEN>
+inline nsresult NS_NewNamedThread(
+    const char (&aName)[LEN], nsIThread** aResult,
+    already_AddRefed<nsIRunnable> aInitialEvent,
+    uint32_t aStackSize = nsIThreadManager::DEFAULT_STACK_SIZE) {
+  static_assert(LEN <= 16, "Thread name must be no more than 16 characters");
+  return NS_NewNamedThread(nsDependentCString(aName, LEN - 1), aResult,
+                           std::move(aInitialEvent), aStackSize);
+}
+
+template <size_t LEN>
+inline nsresult NS_NewNamedThread(
+    const char (&aName)[LEN], nsIThread** aResult,
+    nsIRunnable* aInitialEvent = nullptr,
+    uint32_t aStackSize = nsIThreadManager::DEFAULT_STACK_SIZE) {
+  nsCOMPtr<nsIRunnable> event = aInitialEvent;
+  static_assert(LEN <= 16, "Thread name must be no more than 16 characters");
+  return NS_NewNamedThread(nsDependentCString(aName, LEN - 1), aResult,
+                           event.forget(), aStackSize);
+}
+
+/**
+ * Get a reference to the current thread, creating it if it does not exist yet.
+ *
+ * @param aResult
+ *   The resulting nsIThread object.
+ */
+extern nsresult NS_GetCurrentThread(nsIThread** aResult);
+
+/**
+ * Dispatch the given event to the current thread.
+ *
+ * @param aEvent
+ *   The event to dispatch.
+ *
+ * @returns NS_ERROR_INVALID_ARG
+ *   If event is null.
+ */
+extern nsresult NS_DispatchToCurrentThread(nsIRunnable* aEvent);
+extern nsresult NS_DispatchToCurrentThread(
+    already_AddRefed<nsIRunnable>&& aEvent);
+
+/**
+ * Dispatch the given event to the main thread.
+ *
+ * @param aEvent
+ *   The event to dispatch.
+ * @param aDispatchFlags
+ *   The flags to pass to the main thread's dispatch method.
+ *
+ * @returns NS_ERROR_INVALID_ARG
+ *   If event is null.
+ */
+extern nsresult NS_DispatchToMainThread(
+    nsIRunnable* aEvent, uint32_t aDispatchFlags = NS_DISPATCH_NORMAL);
+extern nsresult NS_DispatchToMainThread(
+    already_AddRefed<nsIRunnable>&& aEvent,
+    uint32_t aDispatchFlags = NS_DISPATCH_NORMAL);
+
+extern nsresult NS_DelayedDispatchToCurrentThread(
+    already_AddRefed<nsIRunnable>&& aEvent, uint32_t aDelayMs);
+
+/**
+ * Dispatch the given event to the specified queue of the current thread.
+ *
+ * @param aEvent The event to dispatch.
+ * @param aQueue The event queue for the thread to use
+ *
+ * @returns NS_ERROR_INVALID_ARG
+ *   If event is null.
+ * @returns NS_ERROR_UNEXPECTED
+ *   If the thread is shutting down.
+ */
+extern nsresult NS_DispatchToCurrentThreadQueue(
+    already_AddRefed<nsIRunnable>&& aEvent, mozilla::EventQueuePriority aQueue);
+
+/**
+ * Dispatch the given event to the specified queue of the main thread.
+ *
+ * @param aEvent The event to dispatch.
+ * @param aQueue The event queue for the thread to use
+ *
+ * @returns NS_ERROR_INVALID_ARG
+ *   If event is null.
+ * @returns NS_ERROR_UNEXPECTED
+ *   If the thread is shutting down.
+ */
+extern nsresult NS_DispatchToMainThreadQueue(
+    already_AddRefed<nsIRunnable>&& aEvent, mozilla::EventQueuePriority aQueue);
+
+/**
+ * Dispatch the given event to an idle queue of the current thread.
+ *
+ * @param aEvent The event to dispatch. If the event implements
+ *   nsIIdleRunnable, it will receive a call on
+ *   nsIIdleRunnable::SetTimer when dispatched, with the value of
+ *   aTimeout.
+ *
+ * @param aTimeout The time in milliseconds until the event should be
+ *   moved from an idle queue to the regular queue, if it hasn't been
+ *   executed. If aEvent is also an nsIIdleRunnable, it is expected
+ *   that it should handle the timeout itself, after a call to
+ *   nsIIdleRunnable::SetTimer.
+ *
+ * @param aQueue
+ *   The event queue for the thread to use.  Must be an idle queue
+ *   (Idle or DeferredTimers)
+ *
+ * @returns NS_ERROR_INVALID_ARG
+ *   If event is null.
+ * @returns NS_ERROR_UNEXPECTED
+ *   If the thread is shutting down.
+ */
+extern nsresult NS_DispatchToCurrentThreadQueue(
+    already_AddRefed<nsIRunnable>&& aEvent, uint32_t aTimeout,
+    mozilla::EventQueuePriority aQueue);
+
+/**
+ * Dispatch the given event to a queue of a thread.
+ *
+ * @param aEvent The event to dispatch.
+ * @param aThread The target thread for the dispatch.
+ * @param aQueue The event queue for the thread to use.
+ *
+ * @returns NS_ERROR_INVALID_ARG
+ *   If event is null.
+ * @returns NS_ERROR_UNEXPECTED
+ *   If the thread is shutting down.
+ */
+extern nsresult NS_DispatchToThreadQueue(already_AddRefed<nsIRunnable>&& aEvent,
+                                         nsIThread* aThread,
+                                         mozilla::EventQueuePriority aQueue);
+
+/**
+ * Dispatch the given event to an idle queue of a thread.
+ *
+ * @param aEvent The event to dispatch. If the event implements
+ *   nsIIdleRunnable, it will receive a call on
+ *   nsIIdleRunnable::SetTimer when dispatched, with the value of
+ *   aTimeout.
+ *
+ * @param aTimeout The time in milliseconds until the event should be
+ *   moved from an idle queue to the regular queue, if it hasn't been
+ *   executed. If aEvent is also an nsIIdleRunnable, it is expected
+ *   that it should handle the timeout itself, after a call to
+ *   nsIIdleRunnable::SetTimer.
+ *
+ * @param aThread The target thread for the dispatch.
+ *
+ * @param aQueue
+ *   The event queue for the thread to use.  Must be an idle queue
+ *   (Idle or DeferredTimers)
+ *
+ * @returns NS_ERROR_INVALID_ARG
+ *   If event is null.
+ * @returns NS_ERROR_UNEXPECTED
+ *   If the thread is shutting down.
+ */
+extern nsresult NS_DispatchToThreadQueue(already_AddRefed<nsIRunnable>&& aEvent,
+                                         uint32_t aTimeout, nsIThread* aThread,
+                                         mozilla::EventQueuePriority aQueue);
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+/**
+ * Process all pending events for the given thread before returning.  This
+ * method simply calls ProcessNextEvent on the thread while HasPendingEvents
+ * continues to return true and the time spent in NS_ProcessPendingEvents
+ * does not exceed the given timeout value.
+ *
+ * @param aThread
+ *   The thread object for which to process pending events.  If null, then
+ *   events will be processed for the current thread.
+ * @param aTimeout
+ *   The maximum number of milliseconds to spend processing pending events.
+ *   Events are not pre-empted to honor this timeout.  Rather, the timeout
+ *   value is simply used to determine whether or not to process another event.
+ *   Pass PR_INTERVAL_NO_TIMEOUT to specify no timeout.
+ */
+extern nsresult NS_ProcessPendingEvents(
+    nsIThread* aThread, PRIntervalTime aTimeout = PR_INTERVAL_NO_TIMEOUT);
+#endif
+
+/**
+ * Shortcut for nsIThread::HasPendingEvents.
+ *
+ * It is an error to call this function when the given thread is not the
+ * current thread.  This function will return false if called from some
+ * other thread.
+ *
+ * @param aThread
+ *   The current thread or null.
+ *
+ * @returns
+ *   A boolean value that if "true" indicates that there are pending events
+ *   in the current thread's event queue.
+ */
+extern bool NS_HasPendingEvents(nsIThread* aThread = nullptr);
+
+/**
+ * Shortcut for nsIThread::ProcessNextEvent.
+ *
+ * It is an error to call this function when the given thread is not the
+ * current thread.  This function will simply return false if called
+ * from some other thread.
+ *
+ * @param aThread
+ *   The current thread or null.
+ * @param aMayWait
+ *   A boolean parameter that if "true" indicates that the method may block
+ *   the calling thread to wait for a pending event.
+ *
+ * @returns
+ *   A boolean value that if "true" indicates that an event from the current
+ *   thread's event queue was processed.
+ */
+extern bool NS_ProcessNextEvent(nsIThread* aThread = nullptr,
+                                bool aMayWait = true);
+
+/**
+ * Returns true if we're in the compositor thread.
+ *
+ * We declare this here because the headers required to invoke
+ * CompositorThreadHolder::IsInCompositorThread() also pull in a bunch of system
+ * headers that #define various tokens in a way that can break the build.
+ */
+extern bool NS_IsInCompositorThread();
+
+extern bool NS_IsInCanvasThreadOrWorker();
+
+extern bool NS_IsInVRThread();
+
+//-----------------------------------------------------------------------------
+// Helpers that work with nsCOMPtr:
+
+inline already_AddRefed<nsIThread> do_GetCurrentThread() {
+  nsIThread* thread = nullptr;
+  NS_GetCurrentThread(&thread);
+  return already_AddRefed<nsIThread>(thread);
+}
+
+inline already_AddRefed<nsIThread> do_GetMainThread() {
+  nsIThread* thread = nullptr;
+  NS_GetMainThread(&thread);
+  return already_AddRefed<nsIThread>(thread);
+}
+
+//-----------------------------------------------------------------------------
+
+#ifdef MOZILLA_INTERNAL_API
+// Fast access to the current thread.  Will create an nsIThread if one does not
+// exist already!  Do not release the returned pointer!  If you want to use this
+// pointer from some other thread, then you will need to AddRef it.  Otherwise,
+// you should only consider this pointer valid from code running on the current
+// thread.
+extern nsIThread* NS_GetCurrentThread();
+
+// Exactly the same as NS_GetCurrentThread, except it will not create an
+// nsThread if one does not exist yet. This is useful in cases where you have
+// code that runs on threads that may or may not not be driven by an nsThread
+// event loop, and wish to avoid inadvertently creating a superfluous nsThread.
+extern nsIThread* NS_GetCurrentThreadNoCreate();
+
+/**
+ * Set the name of the current thread. Prefer this function over
+ * PR_SetCurrentThreadName() if possible. The name will also be included in the
+ * crash report.
+ *
+ * @param aName
+ *   Name of the thread. A C language null-terminated string.
+ */
+extern void NS_SetCurrentThreadName(const char* aName);
+#endif
+
+//-----------------------------------------------------------------------------
+
+#ifndef XPCOM_GLUE_AVOID_NSPR
+
+namespace mozilla {
+
+// This class is designed to be subclassed.
+class IdlePeriod : public nsIIdlePeriod {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIIDLEPERIOD
+
+  IdlePeriod() = default;
+
+ protected:
+  virtual ~IdlePeriod() = default;
+
+ private:
+  IdlePeriod(const IdlePeriod&) = delete;
+  IdlePeriod& operator=(const IdlePeriod&) = delete;
+  IdlePeriod& operator=(const IdlePeriod&&) = delete;
+};
+
+// Cancelable runnable methods implement nsICancelableRunnable, and
+// Idle and IdleWithTimer also nsIIdleRunnable.
+enum class RunnableKind { Standard, Cancelable, Idle, IdleWithTimer };
+
+// Implementing nsINamed on Runnable bloats vtables for the hundreds of
+// Runnable subclasses that we have, so we want to avoid that overhead
+// when we're not using nsINamed for anything.
+#  ifndef RELEASE_OR_BETA
+#    define MOZ_COLLECTING_RUNNABLE_TELEMETRY
+#  endif
+
+// This class is designed to be subclassed.
+class Runnable : public nsIRunnable
+#  ifdef MOZ_COLLECTING_RUNNABLE_TELEMETRY
+    ,
+                 public nsINamed
+#  endif
+{
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIRUNNABLE
+#  ifdef MOZ_COLLECTING_RUNNABLE_TELEMETRY
+  NS_DECL_NSINAMED
+#  endif
+
+  Runnable() = delete;
+
+#  ifdef MOZ_COLLECTING_RUNNABLE_TELEMETRY
+  explicit Runnable(const char* aName) : mName(aName) {}
+#  else
+  explicit Runnable(const char* aName) {}
+#  endif
+
+ protected:
+  virtual ~Runnable() = default;
+
+#  ifdef MOZ_COLLECTING_RUNNABLE_TELEMETRY
+  const char* mName = nullptr;
+#  endif
+
+ private:
+  Runnable(const Runnable&) = delete;
+  Runnable& operator=(const Runnable&) = delete;
+  Runnable& operator=(const Runnable&&) = delete;
+};
+
+// This is a base class for tasks that might not be run, such as those that may
+// be dispatched to workers.
+// The owner of an event target will call either Run() or OnDiscard()
+// exactly once.
+// Derived classes should override Run().  An OnDiscard() override may
+// provide cleanup when Run() will not be called.
+class DiscardableRunnable : public Runnable, public nsIDiscardableRunnable {
+ public:
+  NS_DECL_ISUPPORTS_INHERITED
+  // nsIDiscardableRunnable
+  void OnDiscard() override {}
+
+  DiscardableRunnable() = delete;
+  explicit DiscardableRunnable(const char* aName) : Runnable(aName) {}
+
+ protected:
+  virtual ~DiscardableRunnable() = default;
+
+ private:
+  DiscardableRunnable(const DiscardableRunnable&) = delete;
+  DiscardableRunnable& operator=(const DiscardableRunnable&) = delete;
+  DiscardableRunnable& operator=(const DiscardableRunnable&&) = delete;
+};
+
+// This class is designed to be subclassed.
+// Derived classes should override Run() and Cancel() to provide that
+// calling Run() after Cancel() is a no-op.
+class CancelableRunnable : public DiscardableRunnable,
+                           public nsICancelableRunnable {
+ public:
+  NS_DECL_ISUPPORTS_INHERITED
+  // nsIDiscardableRunnable
+  void OnDiscard() override;
+  // nsICancelableRunnable
+  virtual nsresult Cancel() override = 0;
+
+  CancelableRunnable() = delete;
+  explicit CancelableRunnable(const char* aName) : DiscardableRunnable(aName) {}
+
+ protected:
+  virtual ~CancelableRunnable() = default;
+
+ private:
+  CancelableRunnable(const CancelableRunnable&) = delete;
+  CancelableRunnable& operator=(const CancelableRunnable&) = delete;
+  CancelableRunnable& operator=(const CancelableRunnable&&) = delete;
+};
+
+// This class is designed to be subclassed.
+class IdleRunnable : public DiscardableRunnable, public nsIIdleRunnable {
+ public:
+  NS_DECL_ISUPPORTS_INHERITED
+
+  IdleRunnable() : DiscardableRunnable("IdleRunnable") {}
+  explicit IdleRunnable(const char* aName) : DiscardableRunnable(aName) {}
+
+ protected:
+  virtual ~IdleRunnable() = default;
+
+ private:
+  IdleRunnable(const IdleRunnable&) = delete;
+  IdleRunnable& operator=(const IdleRunnable&) = delete;
+  IdleRunnable& operator=(const IdleRunnable&&) = delete;
+};
+
+// This class is designed to be subclassed.
+class CancelableIdleRunnable : public CancelableRunnable,
+                               public nsIIdleRunnable {
+ public:
+  NS_DECL_ISUPPORTS_INHERITED
+
+  CancelableIdleRunnable() : CancelableRunnable("CancelableIdleRunnable") {}
+  explicit CancelableIdleRunnable(const char* aName)
+      : CancelableRunnable(aName) {}
+
+ protected:
+  virtual ~CancelableIdleRunnable() = default;
+
+ private:
+  CancelableIdleRunnable(const CancelableIdleRunnable&) = delete;
+  CancelableIdleRunnable& operator=(const CancelableIdleRunnable&) = delete;
+  CancelableIdleRunnable& operator=(const CancelableIdleRunnable&&) = delete;
+};
+
+// This class is designed to be a wrapper of a real runnable to support event
+// prioritizable.
+class PrioritizableRunnable : public Runnable, public nsIRunnablePriority {
+ public:
+  PrioritizableRunnable(already_AddRefed<nsIRunnable>&& aRunnable,
+                        uint32_t aPriority);
+
+#  ifdef MOZ_COLLECTING_RUNNABLE_TELEMETRY
+  NS_IMETHOD GetName(nsACString& aName) override;
+#  endif
+
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSIRUNNABLE
+  NS_DECL_NSIRUNNABLEPRIORITY
+
+ protected:
+  virtual ~PrioritizableRunnable() = default;
+  ;
+  nsCOMPtr<nsIRunnable> mRunnable;
+  uint32_t mPriority;
+};
+
+extern already_AddRefed<nsIRunnable> CreateMediumHighRunnable(
+    already_AddRefed<nsIRunnable>&& aRunnable);
+
+namespace detail {
+
+// An event that can be used to call a C++11 functions or function objects,
+// including lambdas. The function must have no required arguments, and must
+// return void.
+template <typename StoredFunction>
+class RunnableFunction : public Runnable {
+ public:
+  template <typename F>
+  explicit RunnableFunction(const char* aName, F&& aFunction)
+      : Runnable(aName), mFunction(std::forward<F>(aFunction)) {}
+
+  NS_IMETHOD Run() override {
+    static_assert(std::is_void_v<decltype(mFunction())>,
+                  "The lambda must return void!");
+    mFunction();
+    return NS_OK;
+  }
+
+ private:
+  StoredFunction mFunction;
+};
+
+// Type alias for NS_NewRunnableFunction
+template <typename Function>
+using RunnableFunctionImpl =
+    // Make sure we store a non-reference in nsRunnableFunction.
+    typename detail::RunnableFunction<std::remove_reference_t<Function>>;
+}  // namespace detail
+
+namespace detail {
+
+template <typename CVRemoved>
+struct IsRefcountedSmartPointerHelper : std::false_type {};
+
+template <typename Pointee>
+struct IsRefcountedSmartPointerHelper<RefPtr<Pointee>> : std::true_type {};
+
+template <typename Pointee>
+struct IsRefcountedSmartPointerHelper<nsCOMPtr<Pointee>> : std::true_type {};
+
+}  // namespace detail
+
+template <typename T>
+struct IsRefcountedSmartPointer
+    : detail::IsRefcountedSmartPointerHelper<std::remove_cv_t<T>> {};
+
+namespace detail {
+
+template <typename T, typename CVRemoved>
+struct RemoveSmartPointerHelper {
+  typedef T Type;
+};
+
+template <typename T, typename Pointee>
+struct RemoveSmartPointerHelper<T, RefPtr<Pointee>> {
+  typedef Pointee Type;
+};
+
+template <typename T, typename Pointee>
+struct RemoveSmartPointerHelper<T, nsCOMPtr<Pointee>> {
+  typedef Pointee Type;
+};
+
+}  // namespace detail
+
+template <typename T>
+struct RemoveSmartPointer
+    : detail::RemoveSmartPointerHelper<T, std::remove_cv_t<T>> {};
+
+namespace detail {
+
+template <typename T, typename CVRemoved>
+struct RemoveRawOrSmartPointerHelper {
+  typedef T Type;
+};
+
+template <typename T, typename Pointee>
+struct RemoveRawOrSmartPointerHelper<T, Pointee*> {
+  typedef Pointee Type;
+};
+
+template <typename T, typename Pointee>
+struct RemoveRawOrSmartPointerHelper<T, RefPtr<Pointee>> {
+  typedef Pointee Type;
+};
+
+template <typename T, typename Pointee>
+struct RemoveRawOrSmartPointerHelper<T, nsCOMPtr<Pointee>> {
+  typedef Pointee Type;
+};
+
+}  // namespace detail
+
+template <typename T>
+struct RemoveRawOrSmartPointer
+    : detail::RemoveRawOrSmartPointerHelper<T, std::remove_cv_t<T>> {};
+
+}  // namespace mozilla
+
+inline nsISupports* ToSupports(mozilla::Runnable* p) {
+  return static_cast<nsIRunnable*>(p);
+}
+
+template <typename Function>
+already_AddRefed<mozilla::Runnable> NS_NewRunnableFunction(
+    const char* aName, Function&& aFunction) {
+  // We store a non-reference in RunnableFunction, but still forward aFunction
+  // to move if possible.
+  return do_AddRef(new mozilla::detail::RunnableFunctionImpl<Function>(
+      aName, std::forward<Function>(aFunction)));
+}
+
+// Creates a new object implementing nsIRunnable and nsICancelableRunnable,
+// which runs a given function on Run and clears the stored function object on a
+// call to `Cancel` (and thus destroys all objects it holds).
+template <typename Function>
+already_AddRefed<mozilla::CancelableRunnable> NS_NewCancelableRunnableFunction(
+    const char* aName, Function&& aFunc) {
+  class FuncCancelableRunnable final : public mozilla::CancelableRunnable {
+   public:
+    static_assert(std::is_void_v<decltype(
+                      std::declval<std::remove_reference_t<Function>>()())>);
+
+    NS_INLINE_DECL_REFCOUNTING_INHERITED(FuncCancelableRunnable,
+                                         CancelableRunnable)
+
+    explicit FuncCancelableRunnable(const char* aName, Function&& aFunc)
+        : CancelableRunnable{aName},
+          mFunc{mozilla::Some(std::forward<Function>(aFunc))} {}
+
+    NS_IMETHOD Run() override {
+      if (mFunc) {
+        (*mFunc)();
+      }
+
+      return NS_OK;
+    }
+
+    nsresult Cancel() override {
+      mFunc.reset();
+      return NS_OK;
+    }
+
+   private:
+    ~FuncCancelableRunnable() = default;
+
+    mozilla::Maybe<std::remove_reference_t<Function>> mFunc;
+  };
+
+  return mozilla::MakeAndAddRef<FuncCancelableRunnable>(
+      aName, std::forward<Function>(aFunc));
+}
+
+namespace mozilla {
+namespace detail {
+
+template <RunnableKind Kind>
+class TimerBehaviour {
+ public:
+  nsITimer* GetTimer() { return nullptr; }
+  void CancelTimer() {}
+
+ protected:
+  ~TimerBehaviour() = default;
+};
+
+template <>
+class TimerBehaviour<RunnableKind::IdleWithTimer> {
+ public:
+  nsITimer* GetTimer() {
+    if (!mTimer) {
+      mTimer = NS_NewTimer();
+    }
+
+    return mTimer;
+  }
+
+  void CancelTimer() {
+    if (mTimer) {
+      mTimer->Cancel();
+    }
+  }
+
+ protected:
+  ~TimerBehaviour() { CancelTimer(); }
+
+ private:
+  nsCOMPtr<nsITimer> mTimer;
+};
+
+}  // namespace detail
+}  // namespace mozilla
+
+// An event that can be used to call a method on a class.  The class type must
+// support reference counting. This event supports Revoke for use
+// with nsRevocableEventPtr.
+template <class ClassType, typename ReturnType = void, bool Owning = true,
+          mozilla::RunnableKind Kind = mozilla::RunnableKind::Standard>
+class nsRunnableMethod
+    : public std::conditional_t<
+          Kind == mozilla::RunnableKind::Standard, mozilla::Runnable,
+          std::conditional_t<Kind == mozilla::RunnableKind::Cancelable,
+                             mozilla::CancelableRunnable,
+                             mozilla::CancelableIdleRunnable>>,
+      protected mozilla::detail::TimerBehaviour<Kind> {
+  using BaseType = std::conditional_t<
+      Kind == mozilla::RunnableKind::Standard, mozilla::Runnable,
+      std::conditional_t<Kind == mozilla::RunnableKind::Cancelable,
+                         mozilla::CancelableRunnable,
+                         mozilla::CancelableIdleRunnable>>;
+
+ public:
+  nsRunnableMethod(const char* aName) : BaseType(aName) {}
+
+  virtual void Revoke() = 0;
+
+  // These ReturnTypeEnforcer classes disallow return types that
+  // we know are not safe. The default ReturnTypeEnforcer compiles just fine but
+  // already_AddRefed will not.
+  template <typename OtherReturnType>
+  class ReturnTypeEnforcer {
+   public:
+    typedef int ReturnTypeIsSafe;
+  };
+
+  template <class T>
+  class ReturnTypeEnforcer<already_AddRefed<T>> {
+    // No ReturnTypeIsSafe makes this illegal!
+  };
+
+  // Make sure this return type is safe.
+  typedef typename ReturnTypeEnforcer<ReturnType>::ReturnTypeIsSafe check;
+};
+
+template <class ClassType, bool Owning>
+struct nsRunnableMethodReceiver {
+  RefPtr<ClassType> mObj;
+  explicit nsRunnableMethodReceiver(ClassType* aObj) : mObj(aObj) {}
+  explicit nsRunnableMethodReceiver(RefPtr<ClassType>&& aObj)
+      : mObj(std::move(aObj)) {}
+  ~nsRunnableMethodReceiver() { Revoke(); }
+  ClassType* Get() const { return mObj.get(); }
+  void Revoke() { mObj = nullptr; }
+};
+
+template <class ClassType>
+struct nsRunnableMethodReceiver<ClassType, false> {
+  ClassType* MOZ_NON_OWNING_REF mObj;
+  explicit nsRunnableMethodReceiver(ClassType* aObj) : mObj(aObj) {}
+  ClassType* Get() const { return mObj; }
+  void Revoke() { mObj = nullptr; }
+};
+
+static inline constexpr bool IsIdle(mozilla::RunnableKind aKind) {
+  return aKind == mozilla::RunnableKind::Idle ||
+         aKind == mozilla::RunnableKind::IdleWithTimer;
+}
+
+template <typename PtrType, typename Method, bool Owning,
+          mozilla::RunnableKind Kind>
+struct nsRunnableMethodTraits;
+
+template <typename PtrType, class C, typename R, bool Owning,
+          mozilla::RunnableKind Kind, typename... As>
+struct nsRunnableMethodTraits<PtrType, R (C::*)(As...), Owning, Kind> {
+  typedef typename mozilla::RemoveRawOrSmartPointer<PtrType>::Type class_type;
+  static_assert(std::is_base_of<C, class_type>::value,
+                "Stored class must inherit from method's class");
+  typedef R return_type;
+  typedef nsRunnableMethod<C, R, Owning, Kind> base_type;
+  static const bool can_cancel = Kind == mozilla::RunnableKind::Cancelable;
+};
+
+template <typename PtrType, class C, typename R, bool Owning,
+          mozilla::RunnableKind Kind, typename... As>
+struct nsRunnableMethodTraits<PtrType, R (C::*)(As...) const, Owning, Kind> {
+  typedef const typename mozilla::RemoveRawOrSmartPointer<PtrType>::Type
+      class_type;
+  static_assert(std::is_base_of<C, class_type>::value,
+                "Stored class must inherit from method's class");
+  typedef R return_type;
+  typedef nsRunnableMethod<C, R, Owning, Kind> base_type;
+  static const bool can_cancel = Kind == mozilla::RunnableKind::Cancelable;
+};
+
+#  ifdef NS_HAVE_STDCALL
+template <typename PtrType, class C, typename R, bool Owning,
+          mozilla::RunnableKind Kind, typename... As>
+struct nsRunnableMethodTraits<PtrType, R (__stdcall C::*)(As...), Owning,
+                              Kind> {
+  typedef typename mozilla::RemoveRawOrSmartPointer<PtrType>::Type class_type;
+  static_assert(std::is_base_of<C, class_type>::value,
+                "Stored class must inherit from method's class");
+  typedef R return_type;
+  typedef nsRunnableMethod<C, R, Owning, Kind> base_type;
+  static const bool can_cancel = Kind == mozilla::RunnableKind::Cancelable;
+};
+
+template <typename PtrType, class C, typename R, bool Owning,
+          mozilla::RunnableKind Kind>
+struct nsRunnableMethodTraits<PtrType, R (NS_STDCALL C::*)(), Owning, Kind> {
+  typedef typename mozilla::RemoveRawOrSmartPointer<PtrType>::Type class_type;
+  static_assert(std::is_base_of<C, class_type>::value,
+                "Stored class must inherit from method's class");
+  typedef R return_type;
+  typedef nsRunnableMethod<C, R, Owning, Kind> base_type;
+  static const bool can_cancel = Kind == mozilla::RunnableKind::Cancelable;
+};
+
+template <typename PtrType, class C, typename R, bool Owning,
+          mozilla::RunnableKind Kind, typename... As>
+struct nsRunnableMethodTraits<PtrType, R (__stdcall C::*)(As...) const, Owning,
+                              Kind> {
+  typedef const typename mozilla::RemoveRawOrSmartPointer<PtrType>::Type
+      class_type;
+  static_assert(std::is_base_of<C, class_type>::value,
+                "Stored class must inherit from method's class");
+  typedef R return_type;
+  typedef nsRunnableMethod<C, R, Owning, Kind> base_type;
+  static const bool can_cancel = Kind == mozilla::RunnableKind::Cancelable;
+};
+
+template <typename PtrType, class C, typename R, bool Owning,
+          mozilla::RunnableKind Kind>
+struct nsRunnableMethodTraits<PtrType, R (NS_STDCALL C::*)() const, Owning,
+                              Kind> {
+  typedef const typename mozilla::RemoveRawOrSmartPointer<PtrType>::Type
+      class_type;
+  static_assert(std::is_base_of<C, class_type>::value,
+                "Stored class must inherit from method's class");
+  typedef R return_type;
+  typedef nsRunnableMethod<C, R, Owning, Kind> base_type;
+  static const bool can_cancel = Kind == mozilla::RunnableKind::Cancelable;
+};
+#  endif
+
+// IsParameterStorageClass<T>::value is true if T is a parameter-storage class
+// that will be recognized by NS_New[NonOwning]RunnableMethodWithArg[s] to
+// force a specific storage&passing strategy (instead of inferring one,
+// see ParameterStorage).
+// When creating a new storage class, add a specialization for it to be
+// recognized.
+template <typename T>
+struct IsParameterStorageClass : public std::false_type {};
+
+// StoreXPassByY structs used to inform nsRunnableMethodArguments how to
+// store arguments, and how to pass them to the target method.
+
+template <typename T>
+struct StoreCopyPassByValue {
+  using stored_type = std::decay_t<T>;
+  typedef stored_type passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreCopyPassByValue(A&& a) : m(std::forward<A>(a)) {}
+  passed_type PassAsParameter() { return m; }
+};
+template <typename S>
+struct IsParameterStorageClass<StoreCopyPassByValue<S>>
+    : public std::true_type {};
+
+template <typename T>
+struct StoreCopyPassByConstLRef {
+  using stored_type = std::decay_t<T>;
+  typedef const stored_type& passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreCopyPassByConstLRef(A&& a) : m(std::forward<A>(a)) {}
+  passed_type PassAsParameter() { return m; }
+};
+template <typename S>
+struct IsParameterStorageClass<StoreCopyPassByConstLRef<S>>
+    : public std::true_type {};
+
+template <typename T>
+struct StoreCopyPassByLRef {
+  using stored_type = std::decay_t<T>;
+  typedef stored_type& passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreCopyPassByLRef(A&& a) : m(std::forward<A>(a)) {}
+  passed_type PassAsParameter() { return m; }
+};
+template <typename S>
+struct IsParameterStorageClass<StoreCopyPassByLRef<S>> : public std::true_type {
+};
+
+template <typename T>
+struct StoreCopyPassByRRef {
+  using stored_type = std::decay_t<T>;
+  typedef stored_type&& passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreCopyPassByRRef(A&& a) : m(std::forward<A>(a)) {}
+  passed_type PassAsParameter() { return std::move(m); }
+};
+template <typename S>
+struct IsParameterStorageClass<StoreCopyPassByRRef<S>> : public std::true_type {
+};
+
+template <typename T>
+struct StoreRefPassByLRef {
+  typedef T& stored_type;
+  typedef T& passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreRefPassByLRef(A& a) : m(a) {}
+  passed_type PassAsParameter() { return m; }
+};
+template <typename S>
+struct IsParameterStorageClass<StoreRefPassByLRef<S>> : public std::true_type {
+};
+
+template <typename T>
+struct StoreConstRefPassByConstLRef {
+  typedef const T& stored_type;
+  typedef const T& passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreConstRefPassByConstLRef(const A& a) : m(a) {}
+  passed_type PassAsParameter() { return m; }
+};
+template <typename S>
+struct IsParameterStorageClass<StoreConstRefPassByConstLRef<S>>
+    : public std::true_type {};
+
+template <typename T>
+struct StoreRefPtrPassByPtr {
+  typedef RefPtr<T> stored_type;
+  typedef T* passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreRefPtrPassByPtr(A&& a) : m(std::forward<A>(a)) {}
+  passed_type PassAsParameter() { return m.get(); }
+};
+template <typename S>
+struct IsParameterStorageClass<StoreRefPtrPassByPtr<S>>
+    : public std::true_type {};
+
+template <typename T>
+struct StorePtrPassByPtr {
+  typedef T* stored_type;
+  typedef T* passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StorePtrPassByPtr(A a) : m(a) {}
+  passed_type PassAsParameter() { return m; }
+};
+template <typename S>
+struct IsParameterStorageClass<StorePtrPassByPtr<S>> : public std::true_type {};
+
+template <typename T>
+struct StoreConstPtrPassByConstPtr {
+  typedef const T* stored_type;
+  typedef const T* passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreConstPtrPassByConstPtr(A a) : m(a) {}
+  passed_type PassAsParameter() { return m; }
+};
+template <typename S>
+struct IsParameterStorageClass<StoreConstPtrPassByConstPtr<S>>
+    : public std::true_type {};
+
+template <typename T>
+struct StoreCopyPassByConstPtr {
+  typedef T stored_type;
+  typedef const T* passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreCopyPassByConstPtr(A&& a) : m(std::forward<A>(a)) {}
+  passed_type PassAsParameter() { return &m; }
+};
+template <typename S>
+struct IsParameterStorageClass<StoreCopyPassByConstPtr<S>>
+    : public std::true_type {};
+
+template <typename T>
+struct StoreCopyPassByPtr {
+  typedef T stored_type;
+  typedef T* passed_type;
+  stored_type m;
+  template <typename A>
+  MOZ_IMPLICIT StoreCopyPassByPtr(A&& a) : m(std::forward<A>(a)) {}
+  passed_type PassAsParameter() { return &m; }
+};
+template <typename S>
+struct IsParameterStorageClass<StoreCopyPassByPtr<S>> : public std::true_type {
+};
+
+namespace detail {
+
+template <typename>
+struct SFINAE1True : std::true_type {};
+
+template <class T>
+static auto HasRefCountMethodsTest(int)
+    -> SFINAE1True<decltype(std::declval<T>().AddRef(),
+                            std::declval<T>().Release())>;
+template <class>
+static auto HasRefCountMethodsTest(long) -> std::false_type;
+
+template <class T>
+struct HasRefCountMethods : decltype(HasRefCountMethodsTest<T>(0)) {};
+
+template <typename TWithoutPointer>
+struct NonnsISupportsPointerStorageClass
+    : std::conditional<
+          std::is_const_v<TWithoutPointer>,
+          StoreConstPtrPassByConstPtr<std::remove_const_t<TWithoutPointer>>,
+          StorePtrPassByPtr<TWithoutPointer>> {
+  using Type = typename NonnsISupportsPointerStorageClass::conditional::type;
+};
+
+template <typename TWithoutPointer>
+struct PointerStorageClass
+    : std::conditional<
+          HasRefCountMethods<TWithoutPointer>::value,
+          StoreRefPtrPassByPtr<TWithoutPointer>,
+          typename NonnsISupportsPointerStorageClass<TWithoutPointer>::Type> {
+  using Type = typename PointerStorageClass::conditional::type;
+};
+
+template <typename TWithoutRef>
+struct LValueReferenceStorageClass
+    : std::conditional<
+          std::is_const_v<TWithoutRef>,
+          StoreConstRefPassByConstLRef<std::remove_const_t<TWithoutRef>>,
+          StoreRefPassByLRef<TWithoutRef>> {
+  using Type = typename LValueReferenceStorageClass::conditional::type;
+};
+
+template <typename T>
+struct SmartPointerStorageClass
+    : std::conditional<
+          mozilla::IsRefcountedSmartPointer<T>::value,
+          StoreRefPtrPassByPtr<typename mozilla::RemoveSmartPointer<T>::Type>,
+          StoreCopyPassByConstLRef<T>> {
+  using Type = typename SmartPointerStorageClass::conditional::type;
+};
+
+template <typename T>
+struct NonLValueReferenceStorageClass
+    : std::conditional<std::is_rvalue_reference_v<T>,
+                       StoreCopyPassByRRef<std::remove_reference_t<T>>,
+                       typename SmartPointerStorageClass<T>::Type> {
+  using Type = typename NonLValueReferenceStorageClass::conditional::type;
+};
+
+template <typename T>
+struct NonPointerStorageClass
+    : std::conditional<std::is_lvalue_reference_v<T>,
+                       typename LValueReferenceStorageClass<
+                           std::remove_reference_t<T>>::Type,
+                       typename NonLValueReferenceStorageClass<T>::Type> {
+  using Type = typename NonPointerStorageClass::conditional::type;
+};
+
+template <typename T>
+struct NonParameterStorageClass
+    : std::conditional<
+          std::is_pointer_v<T>,
+          typename PointerStorageClass<std::remove_pointer_t<T>>::Type,
+          typename NonPointerStorageClass<T>::Type> {
+  using Type = typename NonParameterStorageClass::conditional::type;
+};
+
+// Choose storage&passing strategy based on preferred storage type:
+// - If IsParameterStorageClass<T>::value is true, use as-is.
+// - RC*       -> StoreRefPtrPassByPtr<RC>       :Store RefPtr<RC>, pass RC*
+//   ^^ RC quacks like a ref-counted type (i.e., has AddRef and Release methods)
+// - const T*  -> StoreConstPtrPassByConstPtr<T> :Store const T*, pass const T*
+// - T*        -> StorePtrPassByPtr<T>           :Store T*, pass T*.
+// - const T&  -> StoreConstRefPassByConstLRef<T>:Store const T&, pass const T&.
+// - T&        -> StoreRefPassByLRef<T>          :Store T&, pass T&.
+// - T&&       -> StoreCopyPassByRRef<T>         :Store T, pass std::move(T).
+// - RefPtr<T>, nsCOMPtr<T>
+//             -> StoreRefPtrPassByPtr<T>        :Store RefPtr<T>, pass T*
+// - Other T   -> StoreCopyPassByConstLRef<T>    :Store T, pass const T&.
+// Other available explicit options:
+// -              StoreCopyPassByValue<T>        :Store T, pass T.
+// -              StoreCopyPassByLRef<T>         :Store T, pass T& (of copy!)
+// -              StoreCopyPassByConstPtr<T>     :Store T, pass const T*
+// -              StoreCopyPassByPtr<T>          :Store T, pass T* (of copy!)
+// Or create your own class with PassAsParameter() method, optional
+// clean-up in destructor, and with associated IsParameterStorageClass<>.
+template <typename T>
+struct ParameterStorage
+    : std::conditional<IsParameterStorageClass<T>::value, T,
+                       typename NonParameterStorageClass<T>::Type> {
+  using Type = typename ParameterStorage::conditional::type;
+};
+
+template <class T>
+static auto HasSetDeadlineTest(int) -> SFINAE1True<decltype(
+    std::declval<T>().SetDeadline(std::declval<mozilla::TimeStamp>()))>;
+
+template <class T>
+static auto HasSetDeadlineTest(long) -> std::false_type;
+
+template <class T>
+struct HasSetDeadline : decltype(HasSetDeadlineTest<T>(0)) {};
+
+template <class T>
+std::enable_if_t<::detail::HasSetDeadline<T>::value> SetDeadlineImpl(
+    T* aObj, mozilla::TimeStamp aTimeStamp) {
+  aObj->SetDeadline(aTimeStamp);
+}
+
+template <class T>
+std::enable_if_t<!::detail::HasSetDeadline<T>::value> SetDeadlineImpl(
+    T* aObj, mozilla::TimeStamp aTimeStamp) {}
+} /* namespace detail */
+
+namespace mozilla {
+namespace detail {
+
+// struct used to store arguments and later apply them to a method.
+template <typename... Ts>
+struct RunnableMethodArguments final {
+  Tuple<typename ::detail::ParameterStorage<Ts>::Type...> mArguments;
+  template <typename... As>
+  explicit RunnableMethodArguments(As&&... aArguments)
+      : mArguments(std::forward<As>(aArguments)...) {}
+  template <typename C, typename M, typename... Args, size_t... Indices>
+  static auto applyImpl(C* o, M m, Tuple<Args...>& args,
+                        std::index_sequence<Indices...>)
+      -> decltype(((*o).*m)(Get<Indices>(args).PassAsParameter()...)) {
+    return ((*o).*m)(Get<Indices>(args).PassAsParameter()...);
+  }
+  template <class C, typename M>
+  auto apply(C* o, M m)
+      -> decltype(applyImpl(o, m, mArguments,
+                            std::index_sequence_for<Ts...>{})) {
+    return applyImpl(o, m, mArguments, std::index_sequence_for<Ts...>{});
+  }
+};
+
+template <typename PtrType, typename Method, bool Owning, RunnableKind Kind,
+          typename... Storages>
+class RunnableMethodImpl final
+    : public ::nsRunnableMethodTraits<PtrType, Method, Owning,
+                                      Kind>::base_type {
+  typedef typename ::nsRunnableMethodTraits<PtrType, Method, Owning, Kind>
+      Traits;
+
+  typedef typename Traits::class_type ClassType;
+  typedef typename Traits::base_type BaseType;
+  ::nsRunnableMethodReceiver<ClassType, Owning> mReceiver;
+  Method mMethod;
+  RunnableMethodArguments<Storages...> mArgs;
+  using BaseType::CancelTimer;
+  using BaseType::GetTimer;
+
+ private:
+  virtual ~RunnableMethodImpl() { Revoke(); };
+  static void TimedOut(nsITimer* aTimer, void* aClosure) {
+    static_assert(IsIdle(Kind), "Don't use me!");
+    RefPtr<CancelableIdleRunnable> r =
+        static_cast<CancelableIdleRunnable*>(aClosure);
+    r->SetDeadline(TimeStamp());
+    r->Run();
+    r->Cancel();
+  }
+
+ public:
+  template <typename ForwardedPtrType, typename... Args>
+  explicit RunnableMethodImpl(const char* aName, ForwardedPtrType&& aObj,
+                              Method aMethod, Args&&... aArgs)
+      : BaseType(aName),
+        mReceiver(std::forward<ForwardedPtrType>(aObj)),
+        mMethod(aMethod),
+        mArgs(std::forward<Args>(aArgs)...) {
+    static_assert(sizeof...(Storages) == sizeof...(Args),
+                  "Storages and Args should have equal sizes");
+  }
+
+  NS_IMETHOD Run() {
+    CancelTimer();
+
+    if (MOZ_LIKELY(mReceiver.Get())) {
+      mArgs.apply(mReceiver.Get(), mMethod);
+    }
+
+    return NS_OK;
+  }
+
+  nsresult Cancel() {
+    static_assert(Kind >= RunnableKind::Cancelable, "Don't use me!");
+    Revoke();
+    return NS_OK;
+  }
+
+  void Revoke() {
+    CancelTimer();
+    mReceiver.Revoke();
+  }
+
+  void SetDeadline(TimeStamp aDeadline) {
+    if (MOZ_LIKELY(mReceiver.Get())) {
+      ::detail::SetDeadlineImpl(mReceiver.Get(), aDeadline);
+    }
+  }
+
+  void SetTimer(uint32_t aDelay, nsIEventTarget* aTarget) {
+    MOZ_ASSERT(aTarget);
+
+    if (nsCOMPtr<nsITimer> timer = GetTimer()) {
+      timer->Cancel();
+      timer->SetTarget(aTarget);
+      timer->InitWithNamedFuncCallback(TimedOut, this, aDelay,
+                                       nsITimer::TYPE_ONE_SHOT,
+                                       "detail::RunnableMethodImpl::SetTimer");
+    }
+  }
+};
+
+// Type aliases for NewRunnableMethod.
+template <typename PtrType, typename Method>
+using OwningRunnableMethod =
+    typename ::nsRunnableMethodTraits<std::remove_reference_t<PtrType>, Method,
+                                      true, RunnableKind::Standard>::base_type;
+template <typename PtrType, typename Method, typename... Storages>
+using OwningRunnableMethodImpl =
+    RunnableMethodImpl<std::remove_reference_t<PtrType>, Method, true,
+                       RunnableKind::Standard, Storages...>;
+
+// Type aliases for NewCancelableRunnableMethod.
+template <typename PtrType, typename Method>
+using CancelableRunnableMethod =
+    typename ::nsRunnableMethodTraits<std::remove_reference_t<PtrType>, Method,
+                                      true,
+                                      RunnableKind::Cancelable>::base_type;
+template <typename PtrType, typename Method, typename... Storages>
+using CancelableRunnableMethodImpl =
+    RunnableMethodImpl<std::remove_reference_t<PtrType>, Method, true,
+                       RunnableKind::Cancelable, Storages...>;
+
+// Type aliases for NewIdleRunnableMethod.
+template <typename PtrType, typename Method>
+using IdleRunnableMethod =
+    typename ::nsRunnableMethodTraits<std::remove_reference_t<PtrType>, Method,
+                                      true, RunnableKind::Idle>::base_type;
+template <typename PtrType, typename Method, typename... Storages>
+using IdleRunnableMethodImpl =
+    RunnableMethodImpl<std::remove_reference_t<PtrType>, Method, true,
+                       RunnableKind::Idle, Storages...>;
+
+// Type aliases for NewIdleRunnableMethodWithTimer.
+template <typename PtrType, typename Method>
+using IdleRunnableMethodWithTimer =
+    typename ::nsRunnableMethodTraits<std::remove_reference_t<PtrType>, Method,
+                                      true,
+                                      RunnableKind::IdleWithTimer>::base_type;
+template <typename PtrType, typename Method, typename... Storages>
+using IdleRunnableMethodWithTimerImpl =
+    RunnableMethodImpl<std::remove_reference_t<PtrType>, Method, true,
+                       RunnableKind::IdleWithTimer, Storages...>;
+
+// Type aliases for NewNonOwningRunnableMethod.
+template <typename PtrType, typename Method>
+using NonOwningRunnableMethod =
+    typename ::nsRunnableMethodTraits<std::remove_reference_t<PtrType>, Method,
+                                      false, RunnableKind::Standard>::base_type;
+template <typename PtrType, typename Method, typename... Storages>
+using NonOwningRunnableMethodImpl =
+    RunnableMethodImpl<std::remove_reference_t<PtrType>, Method, false,
+                       RunnableKind::Standard, Storages...>;
+
+// Type aliases for NonOwningCancelableRunnableMethod
+template <typename PtrType, typename Method>
+using NonOwningCancelableRunnableMethod =
+    typename ::nsRunnableMethodTraits<std::remove_reference_t<PtrType>, Method,
+                                      false,
+                                      RunnableKind::Cancelable>::base_type;
+template <typename PtrType, typename Method, typename... Storages>
+using NonOwningCancelableRunnableMethodImpl =
+    RunnableMethodImpl<std::remove_reference_t<PtrType>, Method, false,
+                       RunnableKind::Cancelable, Storages...>;
+
+// Type aliases for NonOwningIdleRunnableMethod
+template <typename PtrType, typename Method>
+using NonOwningIdleRunnableMethod =
+    typename ::nsRunnableMethodTraits<std::remove_reference_t<PtrType>, Method,
+                                      false, RunnableKind::Idle>::base_type;
+template <typename PtrType, typename Method, typename... Storages>
+using NonOwningIdleRunnableMethodImpl =
+    RunnableMethodImpl<std::remove_reference_t<PtrType>, Method, false,
+                       RunnableKind::Idle, Storages...>;
+
+// Type aliases for NewIdleRunnableMethodWithTimer.
+template <typename PtrType, typename Method>
+using NonOwningIdleRunnableMethodWithTimer =
+    typename ::nsRunnableMethodTraits<std::remove_reference_t<PtrType>, Method,
+                                      false,
+                                      RunnableKind::IdleWithTimer>::base_type;
+template <typename PtrType, typename Method, typename... Storages>
+using NonOwningIdleRunnableMethodWithTimerImpl =
+    RunnableMethodImpl<std::remove_reference_t<PtrType>, Method, false,
+                       RunnableKind::IdleWithTimer, Storages...>;
+
+}  // namespace detail
+
+// NewRunnableMethod and friends
+//
+// Very often in Gecko, you'll find yourself in a situation where you want
+// to invoke a method (with or without arguments) asynchronously.  You
+// could write a small helper class inheriting from nsRunnable to handle
+// all these details, or you could let NewRunnableMethod take care of all
+// those details for you.
+//
+// The simplest use of NewRunnableMethod looks like:
+//
+//   nsCOMPtr<nsIRunnable> event =
+//     mozilla::NewRunnableMethod("description", myObject,
+//                                &MyClass::HandleEvent);
+//   NS_DispatchToCurrentThread(event);
+//
+// Statically enforced constraints:
+//  - myObject must be of (or implicitly convertible to) type MyClass
+//  - MyClass must define AddRef and Release methods
+//
+// The "description" string should specify a human-readable name for the
+// runnable; the provided string is used by various introspection tools
+// in the browser.
+//
+// The created runnable will take a strong reference to `myObject`.  For
+// non-refcounted objects, or refcounted objects with unusual refcounting
+// requirements, and if and only if you are 110% certain that `myObject`
+// will live long enough, you can use NewNonOwningRunnableMethod instead,
+// which will, as its name implies, take a non-owning reference.  If you
+// find yourself having to use this function, you should accompany your use
+// with a proof comment describing why the runnable will not lead to
+// use-after-frees.
+//
+// (If you find yourself writing contorted code to Release() an object
+// asynchronously on a different thread, you should use the
+// NS_ProxyRelease function.)
+//
+// Invoking a method with arguments takes a little more care.  The
+// natural extension of the above:
+//
+//   nsCOMPtr<nsIRunnable> event =
+//     mozilla::NewRunnableMethod("description", myObject,
+//                                &MyClass::HandleEvent,
+//                                arg1, arg2, ...);
+//
+// can lead to security hazards (e.g. passing in raw pointers to refcounted
+// objects and storing those raw pointers in the runnable).  We therefore
+// require you to specify the storage types used by the runnable, just as
+// you would if you were writing out the class by hand:
+//
+//   nsCOMPtr<nsIRunnable> event =
+//     mozilla::NewRunnableMethod<RefPtr<T>, nsTArray<U>>
+//         ("description", myObject, &MyClass::HandleEvent, arg1, arg2);
+//
+// Please note that you do not have to pass the same argument type as you
+// specify in the template arguments.  For example, if you want to transfer
+// ownership to a runnable, you can write:
+//
+//   RefPtr<T> ptr = ...;
+//   nsTArray<U> array = ...;
+//   nsCOMPtr<nsIRunnable> event =
+//     mozilla::NewRunnableMethod<RefPtr<T>, nsTArray<U>>
+//         ("description", myObject, &MyClass::DoSomething,
+//          std::move(ptr), std::move(array));
+//
+// and there will be no extra AddRef/Release traffic, or copying of the array.
+//
+// Each type that you specify as a template argument to NewRunnableMethod
+// comes with its own style of storage in the runnable and its own style
+// of argument passing to the invoked method.  See the comment for
+// ParameterStorage above for more details.
+//
+// If you need to customize the storage type and/or argument passing type,
+// you can write your own class to use as a template argument to
+// NewRunnableMethod.  If you find yourself having to do that frequently,
+// please file a bug in Core::XPCOM about adding the custom type to the
+// core code in this file, and/or for custom rules for ParameterStorage
+// to select that strategy.
+//
+// For places that require you to use cancelable runnables, such as
+// workers, there's also NewCancelableRunnableMethod and its non-owning
+// counterpart.  The runnables returned by these methods additionally
+// implement nsICancelableRunnable.
+//
+// Finally, all of the functions discussed above have additional overloads
+// that do not take a `const char*` as their first parameter; you may see
+// these in older code.  The `const char*` overload is preferred and
+// should be used in new code exclusively.
+
+template <typename PtrType, typename Method>
+already_AddRefed<detail::OwningRunnableMethod<PtrType, Method>>
+NewRunnableMethod(const char* aName, PtrType&& aPtr, Method aMethod) {
+  return do_AddRef(new detail::OwningRunnableMethodImpl<PtrType, Method>(
+      aName, std::forward<PtrType>(aPtr), aMethod));
+}
+
+template <typename PtrType, typename Method>
+already_AddRefed<detail::CancelableRunnableMethod<PtrType, Method>>
+NewCancelableRunnableMethod(const char* aName, PtrType&& aPtr, Method aMethod) {
+  return do_AddRef(new detail::CancelableRunnableMethodImpl<PtrType, Method>(
+      aName, std::forward<PtrType>(aPtr), aMethod));
+}
+
+template <typename PtrType, typename Method>
+already_AddRefed<detail::IdleRunnableMethod<PtrType, Method>>
+NewIdleRunnableMethod(const char* aName, PtrType&& aPtr, Method aMethod) {
+  return do_AddRef(new detail::IdleRunnableMethodImpl<PtrType, Method>(
+      aName, std::forward<PtrType>(aPtr), aMethod));
+}
+
+template <typename PtrType, typename Method>
+already_AddRefed<detail::IdleRunnableMethodWithTimer<PtrType, Method>>
+NewIdleRunnableMethodWithTimer(const char* aName, PtrType&& aPtr,
+                               Method aMethod) {
+  return do_AddRef(new detail::IdleRunnableMethodWithTimerImpl<PtrType, Method>(
+      aName, std::forward<PtrType>(aPtr), aMethod));
+}
+
+template <typename PtrType, typename Method>
+already_AddRefed<detail::NonOwningRunnableMethod<PtrType, Method>>
+NewNonOwningRunnableMethod(const char* aName, PtrType&& aPtr, Method aMethod) {
+  return do_AddRef(new detail::NonOwningRunnableMethodImpl<PtrType, Method>(
+      aName, std::forward<PtrType>(aPtr), aMethod));
+}
+
+template <typename PtrType, typename Method>
+already_AddRefed<detail::NonOwningCancelableRunnableMethod<PtrType, Method>>
+NewNonOwningCancelableRunnableMethod(const char* aName, PtrType&& aPtr,
+                                     Method aMethod) {
+  return do_AddRef(
+      new detail::NonOwningCancelableRunnableMethodImpl<PtrType, Method>(
+          aName, std::forward<PtrType>(aPtr), aMethod));
+}
+
+template <typename PtrType, typename Method>
+already_AddRefed<detail::NonOwningIdleRunnableMethod<PtrType, Method>>
+NewNonOwningIdleRunnableMethod(const char* aName, PtrType&& aPtr,
+                               Method aMethod) {
+  return do_AddRef(new detail::NonOwningIdleRunnableMethodImpl<PtrType, Method>(
+      aName, std::forward<PtrType>(aPtr), aMethod));
+}
+
+template <typename PtrType, typename Method>
+already_AddRefed<detail::NonOwningIdleRunnableMethodWithTimer<PtrType, Method>>
+NewNonOwningIdleRunnableMethodWithTimer(const char* aName, PtrType&& aPtr,
+                                        Method aMethod) {
+  return do_AddRef(
+      new detail::NonOwningIdleRunnableMethodWithTimerImpl<PtrType, Method>(
+          aName, std::forward<PtrType>(aPtr), aMethod));
+}
+
+// Similar to NewRunnableMethod. Call like so:
+// nsCOMPtr<nsIRunnable> event =
+//   NewRunnableMethod<Types,...>(myObject, &MyClass::HandleEvent, myArg1,...);
+// 'Types' are the stored type for each argument, see ParameterStorage for
+// details.
+template <typename... Storages, typename PtrType, typename Method,
+          typename... Args>
+already_AddRefed<detail::OwningRunnableMethod<PtrType, Method>>
+NewRunnableMethod(const char* aName, PtrType&& aPtr, Method aMethod,
+                  Args&&... aArgs) {
+  static_assert(sizeof...(Storages) == sizeof...(Args),
+                "<Storages...> size should be equal to number of arguments");
+  return do_AddRef(
+      new detail::OwningRunnableMethodImpl<PtrType, Method, Storages...>(
+          aName, std::forward<PtrType>(aPtr), aMethod,
+          std::forward<Args>(aArgs)...));
+}
+
+template <typename... Storages, typename PtrType, typename Method,
+          typename... Args>
+already_AddRefed<detail::NonOwningRunnableMethod<PtrType, Method>>
+NewNonOwningRunnableMethod(const char* aName, PtrType&& aPtr, Method aMethod,
+                           Args&&... aArgs) {
+  static_assert(sizeof...(Storages) == sizeof...(Args),
+                "<Storages...> size should be equal to number of arguments");
+  return do_AddRef(
+      new detail::NonOwningRunnableMethodImpl<PtrType, Method, Storages...>(
+          aName, std::forward<PtrType>(aPtr), aMethod,
+          std::forward<Args>(aArgs)...));
+}
+
+template <typename... Storages, typename PtrType, typename Method,
+          typename... Args>
+already_AddRefed<detail::CancelableRunnableMethod<PtrType, Method>>
+NewCancelableRunnableMethod(const char* aName, PtrType&& aPtr, Method aMethod,
+                            Args&&... aArgs) {
+  static_assert(sizeof...(Storages) == sizeof...(Args),
+                "<Storages...> size should be equal to number of arguments");
+  return do_AddRef(
+      new detail::CancelableRunnableMethodImpl<PtrType, Method, Storages...>(
+          aName, std::forward<PtrType>(aPtr), aMethod,
+          std::forward<Args>(aArgs)...));
+}
+
+template <typename... Storages, typename PtrType, typename Method,
+          typename... Args>
+already_AddRefed<detail::NonOwningCancelableRunnableMethod<PtrType, Method>>
+NewNonOwningCancelableRunnableMethod(const char* aName, PtrType&& aPtr,
+                                     Method aMethod, Args&&... aArgs) {
+  static_assert(sizeof...(Storages) == sizeof...(Args),
+                "<Storages...> size should be equal to number of arguments");
+  return do_AddRef(
+      new detail::NonOwningCancelableRunnableMethodImpl<PtrType, Method,
+                                                        Storages...>(
+          aName, std::forward<PtrType>(aPtr), aMethod,
+          std::forward<Args>(aArgs)...));
+}
+
+template <typename... Storages, typename PtrType, typename Method,
+          typename... Args>
+already_AddRefed<detail::IdleRunnableMethod<PtrType, Method>>
+NewIdleRunnableMethod(const char* aName, PtrType&& aPtr, Method aMethod,
+                      Args&&... aArgs) {
+  static_assert(sizeof...(Storages) == sizeof...(Args),
+                "<Storages...> size should be equal to number of arguments");
+  return do_AddRef(
+      new detail::IdleRunnableMethodImpl<PtrType, Method, Storages...>(
+          aName, std::forward<PtrType>(aPtr), aMethod,
+          std::forward<Args>(aArgs)...));
+}
+
+template <typename... Storages, typename PtrType, typename Method,
+          typename... Args>
+already_AddRefed<detail::NonOwningIdleRunnableMethod<PtrType, Method>>
+NewNonOwningIdleRunnableMethod(const char* aName, PtrType&& aPtr,
+                               Method aMethod, Args&&... aArgs) {
+  static_assert(sizeof...(Storages) == sizeof...(Args),
+                "<Storages...> size should be equal to number of arguments");
+  return do_AddRef(
+      new detail::NonOwningIdleRunnableMethodImpl<PtrType, Method, Storages...>(
+          aName, std::forward<PtrType>(aPtr), aMethod,
+          std::forward<Args>(aArgs)...));
+}
+
+}  // namespace mozilla
+
+#endif  // XPCOM_GLUE_AVOID_NSPR
+
+// This class is designed to be used when you have an event class E that has a
+// pointer back to resource class R.  If R goes away while E is still pending,
+// then it is important to "revoke" E so that it does not try use R after R has
+// been destroyed.  nsRevocableEventPtr makes it easy for R to manage such
+// situations:
+//
+//   class R;
+//
+//   class E : public mozilla::Runnable {
+//   public:
+//     void Revoke() {
+//       mResource = nullptr;
+//     }
+//   private:
+//     R *mResource;
+//   };
+//
+//   class R {
+//   public:
+//     void EventHandled() {
+//       mEvent.Forget();
+//     }
+//   private:
+//     nsRevocableEventPtr<E> mEvent;
+//   };
+//
+//   void R::PostEvent() {
+//     // Make sure any pending event is revoked.
+//     mEvent->Revoke();
+//
+//     nsCOMPtr<nsIRunnable> event = new E();
+//     if (NS_SUCCEEDED(NS_DispatchToCurrentThread(event))) {
+//       // Keep pointer to event so we can revoke it.
+//       mEvent = event;
+//     }
+//   }
+//
+//   NS_IMETHODIMP E::Run() {
+//     if (!mResource)
+//       return NS_OK;
+//     ...
+//     mResource->EventHandled();
+//     return NS_OK;
+//   }
+//
+template <class T>
+class nsRevocableEventPtr {
+ public:
+  nsRevocableEventPtr() : mEvent(nullptr) {}
+  ~nsRevocableEventPtr() { Revoke(); }
+
+  const nsRevocableEventPtr& operator=(RefPtr<T>&& aEvent) {
+    if (mEvent != aEvent) {
+      Revoke();
+      mEvent = std::move(aEvent);
+    }
+    return *this;
+  }
+
+  void Revoke() {
+    if (mEvent) {
+      mEvent->Revoke();
+      mEvent = nullptr;
+    }
+  }
+
+  void Forget() { mEvent = nullptr; }
+  bool IsPending() { return mEvent != nullptr; }
+  T* get() { return mEvent; }
+
+ private:
+  // Not implemented
+  nsRevocableEventPtr(const nsRevocableEventPtr&);
+  nsRevocableEventPtr& operator=(const nsRevocableEventPtr&);
+
+  RefPtr<T> mEvent;
+};
+
+template <class T>
+inline already_AddRefed<T> do_AddRef(nsRevocableEventPtr<T>& aObj) {
+  return do_AddRef(aObj.get());
+}
+
+/**
+ * A simple helper to suffix thread pool name
+ * with incremental numbers.
+ */
+class nsThreadPoolNaming {
+ public:
+  nsThreadPoolNaming() = default;
+
+  /**
+   * Returns a thread name as "<aPoolName> #<n>" and increments the counter.
+   */
+  nsCString GetNextThreadName(const nsACString& aPoolName);
+
+  template <size_t LEN>
+  nsCString GetNextThreadName(const char (&aPoolName)[LEN]) {
+    return GetNextThreadName(nsDependentCString(aPoolName, LEN - 1));
+  }
+
+ private:
+  mozilla::Atomic<uint32_t> mCounter{0};
+
+  nsThreadPoolNaming(const nsThreadPoolNaming&) = delete;
+  void operator=(const nsThreadPoolNaming&) = delete;
+};
+
+/**
+ * Thread priority in most operating systems affect scheduling, not IO.  This
+ * helper is used to set the current thread to low IO priority for the lifetime
+ * of the created object.  You can only use this low priority IO setting within
+ * the context of the current thread.
+ */
+class MOZ_STACK_CLASS nsAutoLowPriorityIO {
+ public:
+  nsAutoLowPriorityIO();
+  ~nsAutoLowPriorityIO();
+
+ private:
+  bool lowIOPrioritySet;
+#if defined(XP_MACOSX)
+  int oldPriority;
+#endif
+};
+
+void NS_SetMainThread();
+
+// Used only on cooperatively scheduled "main" threads. Causes the thread to be
+// considered a main thread and also causes GetCurrentVirtualThread to return
+// aVirtualThread.
+void NS_SetMainThread(PRThread* aVirtualThread);
+
+// Used only on cooperatively scheduled "main" threads. Causes the thread to no
+// longer be considered a main thread. Also causes GetCurrentVirtualThread() to
+// return a unique value.
+void NS_UnsetMainThread();
+
+/**
+ * Return the expiration time of the next timer to run on the current
+ * thread.  If that expiration time is greater than aDefault, then
+ * return aDefault.  aSearchBound specifies a maximum number of timers
+ * to examine to find a timer on the current thread.  If no timer that
+ * will run on the current thread is found after examining
+ * aSearchBound timers, return the highest seen expiration time as a
+ * best effort guess.
+ *
+ * Timers with either the type nsITimer::TYPE_ONE_SHOT_LOW_PRIORITY or
+ * nsITIMER::TYPE_REPEATING_SLACK_LOW_PRIORITY will be skipped when
+ * searching for the next expiration time.  This enables timers to
+ * have lower priority than callbacks dispatched from
+ * nsIThread::IdleDispatch.
+ */
+extern mozilla::TimeStamp NS_GetTimerDeadlineHintOnCurrentThread(
+    mozilla::TimeStamp aDefault, uint32_t aSearchBound);
+
+/**
+ * Dispatches the given event to a background thread.  The primary benefit of
+ * this API is that you do not have to manage the lifetime of your own thread
+ * for running your own events; the thread manager will take care of the
+ * background thread's lifetime.  Not having to manage your own thread also
+ * means less resource usage, as the underlying implementation here can manage
+ * spinning up and shutting down threads appropriately.
+ *
+ * NOTE: there is no guarantee that events dispatched via these APIs are run
+ * serially, in dispatch order; several dispatched events may run in parallel.
+ * If you depend on serial execution of dispatched events, you should use
+ * NS_CreateBackgroundTaskQueue instead, and dispatch events to the returned
+ * event target.
+ */
+extern nsresult NS_DispatchBackgroundTask(
+    already_AddRefed<nsIRunnable> aEvent,
+    uint32_t aDispatchFlags = NS_DISPATCH_NORMAL);
+extern "C" nsresult NS_DispatchBackgroundTask(
+    nsIRunnable* aEvent, uint32_t aDispatchFlags = NS_DISPATCH_NORMAL);
+
+/**
+ * Obtain a new serial event target that dispatches runnables to a background
+ * thread.  In many cases, this is a straight replacement for creating your
+ * own, private thread, and is generally preferred to creating your own,
+ * private thread.
+ */
+extern "C" nsresult NS_CreateBackgroundTaskQueue(
+    const char* aName, nsISerialEventTarget** aTarget);
+
+// Predeclaration for logging function below
+namespace IPC {
+class Message;
+}
+
+class nsTimerImpl;
+
+namespace mozilla {
+
+// RAII class that will set the TLS entry to return the currently running
+// nsISerialEventTarget.
+// It should be used from inner event loop implementation.
+class SerialEventTargetGuard {
+ public:
+  explicit SerialEventTargetGuard(nsISerialEventTarget* aThread)
+      : mLastCurrentThread(sCurrentThreadTLS.get()) {
+    Set(aThread);
+  }
+
+  ~SerialEventTargetGuard() { sCurrentThreadTLS.set(mLastCurrentThread); }
+
+  static void InitTLS();
+  static nsISerialEventTarget* GetCurrentSerialEventTarget() {
+    return sCurrentThreadTLS.get();
+  }
+
+ protected:
+  friend class ::MessageLoop;
+  static void Set(nsISerialEventTarget* aThread) {
+    MOZ_ASSERT(aThread->IsOnCurrentThread());
+    sCurrentThreadTLS.set(aThread);
+  }
+
+ private:
+  static MOZ_THREAD_LOCAL(nsISerialEventTarget*) sCurrentThreadTLS;
+  nsISerialEventTarget* mLastCurrentThread;
+};
+
+// These functions return event targets that can be used to dispatch to the
+// current or main thread. They can also be used to test if you're on those
+// threads (via IsOnCurrentThread). These functions should be used in preference
+// to the nsIThread-based NS_Get{Current,Main}Thread functions since they will
+// return more useful answers in the case of threads sharing an event loop.
+
+nsIEventTarget* GetCurrentEventTarget();
+
+nsIEventTarget* GetMainThreadEventTarget();
+
+// These variants of the above functions assert that the given thread has a
+// serial event target (i.e., that it's not part of a thread pool) and returns
+// that.
+
+nsISerialEventTarget* GetCurrentSerialEventTarget();
+
+nsISerialEventTarget* GetMainThreadSerialEventTarget();
+
+// Returns a wrapper around the current thread which routes normal dispatches
+// through the tail dispatcher.
+// This means that they will run at the end of the current task, rather than
+// after all the subsequent tasks queued. This is useful to allow MozPromise
+// callbacks returned by IPDL methods to avoid an extra trip through the event
+// loop, and thus maintain correct ordering relative to other IPC events. The
+// current thread implementation must support tail dispatch.
+class TailDispatchingTarget : public nsISerialEventTarget {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  TailDispatchingTarget()
+#if DEBUG
+      : mOwnerThread(AbstractThread::GetCurrent())
+#endif
+  {
+    MOZ_ASSERT(mOwnerThread, "Must be used with AbstractThreads");
+  }
+
+  NS_IMETHOD
+  Dispatch(already_AddRefed<nsIRunnable> event, uint32_t flags) override {
+    MOZ_ASSERT(flags == DISPATCH_NORMAL);
+    MOZ_ASSERT(
+        AbstractThread::GetCurrent() == mOwnerThread,
+        "TailDispatchingTarget can only be used on the thread upon which it "
+        "was created - see the comment on the class declaration.");
+    AbstractThread::DispatchDirectTask(std::move(event));
+    return NS_OK;
+  }
+  NS_IMETHOD_(bool) IsOnCurrentThreadInfallible(void) override { return true; }
+  NS_IMETHOD IsOnCurrentThread(bool* _retval) override {
+    *_retval = true;
+    return NS_OK;
+  }
+  NS_IMETHOD DispatchFromScript(nsIRunnable* event, uint32_t flags) override {
+    MOZ_ASSERT_UNREACHABLE("not implemented");
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+  NS_IMETHOD DelayedDispatch(already_AddRefed<nsIRunnable> event,
+                             uint32_t delay) override {
+    MOZ_ASSERT_UNREACHABLE("not implemented");
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+ private:
+  virtual ~TailDispatchingTarget() = default;
+#if DEBUG
+  const RefPtr<AbstractThread> mOwnerThread;
+#endif
+};
+
+// Returns the number of CPUs, like PR_GetNumberOfProcessors, except
+// that it can return a cached value on platforms where sandboxing
+// would prevent reading the current value (currently Linux).  CPU
+// hotplugging is uncommon, so this is unlikely to make a difference
+// in practice.
+size_t GetNumberOfProcessors();
+
+/**
+ * A helper class to log tasks dispatch and run with "MOZ_LOG=events:1".  The
+ * output is more machine readable and creates a link between dispatch and run.
+ *
+ * Usage example for the concrete template type nsIRunnable.
+ * To log a dispatch, which means putting an event to a queue:
+ *   LogRunnable::LogDispatch(event);
+ *   theQueue.putEvent(event);
+ *
+ * To log execution (running) of the event:
+ *   nsCOMPtr<nsIRunnable> event = theQueue.popEvent();
+ *   {
+ *     LogRunnable::Run log(event);
+ *     event->Run();
+ *     event = null;  // to include the destructor code in the span
+ *   }
+ *
+ * The class is a template so that we can support various specific super-types
+ * of tasks in the future.  We can't use void* because it may cast differently
+ * and tracking the pointer in logs would then be impossible.
+ */
+template <typename T>
+class LogTaskBase {
+ public:
+  LogTaskBase() = delete;
+
+  // Adds a simple log about dispatch of this runnable.
+  static void LogDispatch(T* aEvent);
+  // The `aContext` pointer adds another uniqe identifier, nothing more
+  static void LogDispatch(T* aEvent, void* aContext);
+
+  // Logs dispatch of the message and along that also the PID of the target
+  // proccess, purposed for uniquely identifying IPC messages.
+  static void LogDispatchWithPid(T* aEvent, int32_t aPid);
+
+  // This is designed to surround a call to `Run()` or any code representing
+  // execution of the task body.
+  // The constructor adds a simple log about start of the runnable execution and
+  // the destructor adds a log about ending the execution.
+  class MOZ_RAII Run {
+   public:
+    Run() = delete;
+    explicit Run(T* aEvent, bool aWillRunAgain = false);
+    explicit Run(T* aEvent, void* aContext, bool aWillRunAgain = false);
+    ~Run();
+
+    // When this is called, the log in this RAII dtor will only say
+    // "interrupted" expecting that the event will run again.
+    void WillRunAgain() { mWillRunAgain = true; }
+
+   private:
+    bool mWillRunAgain = false;
+  };
+};
+
+class MicroTaskRunnable;
+class Task;  // TaskController
+class PresShell;
+namespace dom {
+class FrameRequestCallback;
+}  // namespace dom
+
+// Specialized methods must be explicitly predeclared.
+template <>
+LogTaskBase<nsIRunnable>::Run::Run(nsIRunnable* aEvent, bool aWillRunAgain);
+template <>
+LogTaskBase<Task>::Run::Run(Task* aTask, bool aWillRunAgain);
+template <>
+void LogTaskBase<IPC::Message>::LogDispatchWithPid(IPC::Message* aEvent,
+                                                   int32_t aPid);
+template <>
+LogTaskBase<IPC::Message>::Run::Run(IPC::Message* aMessage, bool aWillRunAgain);
+template <>
+LogTaskBase<nsTimerImpl>::Run::Run(nsTimerImpl* aEvent, bool aWillRunAgain);
+
+typedef LogTaskBase<nsIRunnable> LogRunnable;
+typedef LogTaskBase<MicroTaskRunnable> LogMicroTaskRunnable;
+typedef LogTaskBase<IPC::Message> LogIPCMessage;
+typedef LogTaskBase<nsTimerImpl> LogTimerEvent;
+typedef LogTaskBase<Task> LogTask;
+typedef LogTaskBase<PresShell> LogPresShellObserver;
+typedef LogTaskBase<dom::FrameRequestCallback> LogFrameRequestCallback;
+// If you add new types don't forget to add:
+// `template class LogTaskBase<YourType>;` to nsThreadUtils.cpp
+
+class DelayedRunnable : public mozilla::Runnable, public nsITimerCallback {
+ public:
+  DelayedRunnable(already_AddRefed<nsIEventTarget> aTarget,
+                  already_AddRefed<nsIRunnable> aRunnable, uint32_t aDelay);
+
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSIRUNNABLE
+  NS_DECL_NSITIMERCALLBACK
+
+  nsresult Init();
+
+ private:
+  ~DelayedRunnable() = default;
+  nsresult DoRun();
+
+  const nsCOMPtr<nsIEventTarget> mTarget;
+  nsCOMPtr<nsIRunnable> mWrappedRunnable;
+  nsCOMPtr<nsITimer> mTimer;
+  const mozilla::TimeStamp mDelayedFrom;
+  uint32_t mDelay;
+};
+
+}  // namespace mozilla
+
+#endif  // nsThreadUtils_h__