Adding upstream version 124.0.1.upstream/124.0.1

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

1 files changed, 725 insertions, 0 deletions

diff --git a/ipc/chromium/src/base/message_loop.cc b/ipc/chromium/src/base/message_loop.cc
new file mode 100644
index 0000000000..c82d555ee5
--- /dev/null
+++ b/ipc/chromium/src/base/message_loop.cc
@@ -0,0 +1,725 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/message_loop.h"
+
+#include <algorithm>
+
+#include "base/compiler_specific.h"
+#include "base/logging.h"
+#include "base/message_pump_default.h"
+#include "base/string_util.h"
+#include "base/thread_local.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/ProfilerRunnable.h"
+#include "nsIEventTarget.h"
+#include "nsITargetShutdownTask.h"
+#include "nsThreadUtils.h"
+
+#if defined(XP_DARWIN)
+#  include "base/message_pump_mac.h"
+#endif
+#if defined(XP_UNIX)
+#  include "base/message_pump_libevent.h"
+#endif
+#if defined(XP_LINUX) || defined(__DragonFly__) || defined(XP_FREEBSD) || \
+    defined(XP_NETBSD) || defined(XP_OPENBSD)
+#  if defined(MOZ_WIDGET_GTK)
+#    include "base/message_pump_glib.h"
+#  endif
+#endif
+#ifdef ANDROID
+#  include "base/message_pump_android.h"
+#endif
+#include "nsISerialEventTarget.h"
+
+#include "mozilla/ipc/MessagePump.h"
+#include "nsThreadUtils.h"
+
+using base::Time;
+using base::TimeDelta;
+using base::TimeTicks;
+
+using mozilla::Runnable;
+
+static base::ThreadLocalPointer<MessageLoop>& get_tls_ptr() {
+  static base::ThreadLocalPointer<MessageLoop> tls_ptr;
+  return tls_ptr;
+}
+
+//------------------------------------------------------------------------------
+
+#if defined(XP_WIN)
+
+// Upon a SEH exception in this thread, it restores the original unhandled
+// exception filter.
+static int SEHFilter(LPTOP_LEVEL_EXCEPTION_FILTER old_filter) {
+  ::SetUnhandledExceptionFilter(old_filter);
+  return EXCEPTION_CONTINUE_SEARCH;
+}
+
+// Retrieves a pointer to the current unhandled exception filter. There
+// is no standalone getter method.
+static LPTOP_LEVEL_EXCEPTION_FILTER GetTopSEHFilter() {
+  LPTOP_LEVEL_EXCEPTION_FILTER top_filter = NULL;
+  top_filter = ::SetUnhandledExceptionFilter(0);
+  ::SetUnhandledExceptionFilter(top_filter);
+  return top_filter;
+}
+
+#endif  // defined(XP_WIN)
+
+//------------------------------------------------------------------------------
+
+class MessageLoop::EventTarget : public nsISerialEventTarget,
+                                 public nsITargetShutdownTask,
+                                 public MessageLoop::DestructionObserver {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIEVENTTARGET_FULL
+
+  void TargetShutdown() override {
+    nsTArray<nsCOMPtr<nsITargetShutdownTask>> shutdownTasks;
+    {
+      mozilla::MutexAutoLock lock(mMutex);
+      if (mShutdownTasksRun) {
+        return;
+      }
+      mShutdownTasksRun = true;
+      shutdownTasks = std::move(mShutdownTasks);
+      mShutdownTasks.Clear();
+    }
+
+    for (auto& task : shutdownTasks) {
+      task->TargetShutdown();
+    }
+  }
+
+  explicit EventTarget(MessageLoop* aLoop)
+      : mMutex("MessageLoop::EventTarget"), mLoop(aLoop) {
+    aLoop->AddDestructionObserver(this);
+  }
+
+ private:
+  virtual ~EventTarget() {
+    if (mLoop) {
+      mLoop->RemoveDestructionObserver(this);
+    }
+    MOZ_ASSERT(mShutdownTasks.IsEmpty());
+  }
+
+  void WillDestroyCurrentMessageLoop() override {
+    {
+      mozilla::MutexAutoLock lock(mMutex);
+      // The MessageLoop is being destroyed and we are called from its
+      // destructor There's no real need to remove ourselves from the
+      // destruction observer list. But it makes things look tidier.
+      mLoop->RemoveDestructionObserver(this);
+      mLoop = nullptr;
+    }
+
+    TargetShutdown();
+  }
+
+  mozilla::Mutex mMutex;
+  bool mShutdownTasksRun MOZ_GUARDED_BY(mMutex) = false;
+  nsTArray<nsCOMPtr<nsITargetShutdownTask>> mShutdownTasks
+      MOZ_GUARDED_BY(mMutex);
+  MessageLoop* mLoop MOZ_GUARDED_BY(mMutex);
+};
+
+NS_IMPL_ISUPPORTS(MessageLoop::EventTarget, nsIEventTarget,
+                  nsISerialEventTarget)
+
+NS_IMETHODIMP_(bool)
+MessageLoop::EventTarget::IsOnCurrentThreadInfallible() {
+  mozilla::MutexAutoLock lock(mMutex);
+  return mLoop == MessageLoop::current();
+}
+
+NS_IMETHODIMP
+MessageLoop::EventTarget::IsOnCurrentThread(bool* aResult) {
+  *aResult = IsOnCurrentThreadInfallible();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+MessageLoop::EventTarget::DispatchFromScript(nsIRunnable* aEvent,
+                                             uint32_t aFlags) {
+  nsCOMPtr<nsIRunnable> event(aEvent);
+  return Dispatch(event.forget(), aFlags);
+}
+
+NS_IMETHODIMP
+MessageLoop::EventTarget::Dispatch(already_AddRefed<nsIRunnable> aEvent,
+                                   uint32_t aFlags) {
+  mozilla::MutexAutoLock lock(mMutex);
+  if (!mLoop) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  if (aFlags != NS_DISPATCH_NORMAL) {
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  mLoop->PostTask(std::move(aEvent));
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+MessageLoop::EventTarget::DelayedDispatch(already_AddRefed<nsIRunnable> aEvent,
+                                          uint32_t aDelayMs) {
+  mozilla::MutexAutoLock lock(mMutex);
+  if (!mLoop) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  mLoop->PostDelayedTask(std::move(aEvent), aDelayMs);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+MessageLoop::EventTarget::RegisterShutdownTask(nsITargetShutdownTask* aTask) {
+  mozilla::MutexAutoLock lock(mMutex);
+  if (!mLoop || mShutdownTasksRun) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  MOZ_ASSERT(!mShutdownTasks.Contains(aTask));
+  mShutdownTasks.AppendElement(aTask);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+MessageLoop::EventTarget::UnregisterShutdownTask(nsITargetShutdownTask* aTask) {
+  mozilla::MutexAutoLock lock(mMutex);
+  if (!mLoop || mShutdownTasksRun) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  return mShutdownTasks.RemoveElement(aTask) ? NS_OK : NS_ERROR_UNEXPECTED;
+}
+
+//------------------------------------------------------------------------------
+
+// static
+MessageLoop* MessageLoop::current() { return get_tls_ptr().Get(); }
+
+// static
+void MessageLoop::set_current(MessageLoop* loop) { get_tls_ptr().Set(loop); }
+
+static mozilla::Atomic<int32_t> message_loop_id_seq(0);
+
+MessageLoop::MessageLoop(Type type, nsISerialEventTarget* aEventTarget)
+    : type_(type),
+      id_(++message_loop_id_seq),
+      nestable_tasks_allowed_(true),
+      exception_restoration_(false),
+      incoming_queue_lock_("MessageLoop Incoming Queue Lock"),
+      state_(NULL),
+      run_depth_base_(1),
+      shutting_down_(false),
+#ifdef XP_WIN
+      os_modal_loop_(false),
+#endif  // XP_WIN
+      transient_hang_timeout_(0),
+      permanent_hang_timeout_(0),
+      next_sequence_num_(0) {
+  DCHECK(!current()) << "should only have one message loop per thread";
+  get_tls_ptr().Set(this);
+
+  // Must initialize after current() is initialized.
+  mEventTarget = new EventTarget(this);
+
+  switch (type_) {
+    case TYPE_MOZILLA_PARENT:
+      MOZ_RELEASE_ASSERT(!aEventTarget);
+      pump_ = new mozilla::ipc::MessagePump(aEventTarget);
+      return;
+    case TYPE_MOZILLA_CHILD:
+      MOZ_RELEASE_ASSERT(!aEventTarget);
+      pump_ = new mozilla::ipc::MessagePumpForChildProcess();
+      // There is a MessageLoop Run call from XRE_InitChildProcess
+      // and another one from MessagePumpForChildProcess. The one
+      // from MessagePumpForChildProcess becomes the base, so we need
+      // to set run_depth_base_ to 2 or we'll never be able to process
+      // Idle tasks.
+      run_depth_base_ = 2;
+      return;
+    case TYPE_MOZILLA_NONMAINTHREAD:
+      pump_ = new mozilla::ipc::MessagePumpForNonMainThreads(aEventTarget);
+      return;
+#if defined(XP_WIN) || defined(XP_DARWIN)
+    case TYPE_MOZILLA_NONMAINUITHREAD:
+      pump_ = new mozilla::ipc::MessagePumpForNonMainUIThreads(aEventTarget);
+      return;
+#elif defined(MOZ_WIDGET_ANDROID)
+    case TYPE_MOZILLA_ANDROID_UI:
+      MOZ_RELEASE_ASSERT(aEventTarget);
+      pump_ = new mozilla::ipc::MessagePumpForAndroidUI(aEventTarget);
+      return;
+#endif  // defined(MOZ_WIDGET_ANDROID)
+    default:
+      // Create one of Chromium's standard MessageLoop types below.
+      break;
+  }
+
+#if defined(XP_WIN)
+  // TODO(rvargas): Get rid of the OS guards.
+  if (type_ == TYPE_DEFAULT) {
+    pump_ = new base::MessagePumpDefault();
+  } else if (type_ == TYPE_IO) {
+    pump_ = new base::MessagePumpForIO();
+  } else {
+    DCHECK(type_ == TYPE_UI);
+    pump_ = new base::MessagePumpForUI();
+  }
+#else
+  if (type_ == TYPE_UI) {
+#  if defined(XP_DARWIN)
+    pump_ = base::MessagePumpMac::Create();
+#  elif defined(XP_LINUX) || defined(__DragonFly__) || defined(XP_FREEBSD) || \
+      defined(XP_NETBSD) || defined(XP_OPENBSD)
+    pump_ = new base::MessagePumpForUI();
+#  endif  // XP_LINUX
+  } else if (type_ == TYPE_IO) {
+    pump_ = new base::MessagePumpLibevent();
+  } else {
+    pump_ = new base::MessagePumpDefault();
+  }
+#endif
+
+  // We want GetCurrentSerialEventTarget() to return the real nsThread if it
+  // will be used to dispatch tasks. However, under all other cases; we'll want
+  // it to return this MessageLoop's EventTarget.
+  if (nsISerialEventTarget* thread = pump_->GetXPCOMThread()) {
+    MOZ_ALWAYS_SUCCEEDS(thread->RegisterShutdownTask(mEventTarget));
+  } else {
+    mozilla::SerialEventTargetGuard::Set(mEventTarget);
+  }
+}
+
+MessageLoop::~MessageLoop() {
+  DCHECK(this == current());
+
+  // Let interested parties have one last shot at accessing this.
+  FOR_EACH_OBSERVER(DestructionObserver, destruction_observers_,
+                    WillDestroyCurrentMessageLoop());
+
+  DCHECK(!state_);
+
+  // Clean up any unprocessed tasks, but take care: deleting a task could
+  // result in the addition of more tasks (e.g., via DeleteSoon).  We set a
+  // limit on the number of times we will allow a deleted task to generate more
+  // tasks.  Normally, we should only pass through this loop once or twice.  If
+  // we end up hitting the loop limit, then it is probably due to one task that
+  // is being stubborn.  Inspect the queues to see who is left.
+  bool did_work;
+  for (int i = 0; i < 100; ++i) {
+    DeletePendingTasks();
+    ReloadWorkQueue();
+    // If we end up with empty queues, then break out of the loop.
+    did_work = DeletePendingTasks();
+    if (!did_work) break;
+  }
+  DCHECK(!did_work);
+
+  // OK, now make it so that no one can find us.
+  get_tls_ptr().Set(NULL);
+}
+
+void MessageLoop::AddDestructionObserver(DestructionObserver* obs) {
+  DCHECK(this == current());
+  destruction_observers_.AddObserver(obs);
+}
+
+void MessageLoop::RemoveDestructionObserver(DestructionObserver* obs) {
+  DCHECK(this == current());
+  destruction_observers_.RemoveObserver(obs);
+}
+
+void MessageLoop::Run() {
+  AutoRunState save_state(this);
+  RunHandler();
+}
+
+// Runs the loop in two different SEH modes:
+// enable_SEH_restoration_ = false : any unhandled exception goes to the last
+// one that calls SetUnhandledExceptionFilter().
+// enable_SEH_restoration_ = true : any unhandled exception goes to the filter
+// that was existed before the loop was run.
+void MessageLoop::RunHandler() {
+#if defined(XP_WIN)
+  if (exception_restoration_) {
+    LPTOP_LEVEL_EXCEPTION_FILTER current_filter = GetTopSEHFilter();
+    MOZ_SEH_TRY { RunInternal(); }
+    MOZ_SEH_EXCEPT(SEHFilter(current_filter)) {}
+    return;
+  }
+#endif
+
+  RunInternal();
+}
+
+//------------------------------------------------------------------------------
+
+void MessageLoop::RunInternal() {
+  DCHECK(this == current());
+  pump_->Run(this);
+}
+
+//------------------------------------------------------------------------------
+// Wrapper functions for use in above message loop framework.
+
+bool MessageLoop::ProcessNextDelayedNonNestableTask() {
+  if (state_->run_depth > run_depth_base_) return false;
+
+  if (deferred_non_nestable_work_queue_.empty()) return false;
+
+  nsCOMPtr<nsIRunnable> task =
+      std::move(deferred_non_nestable_work_queue_.front().task);
+  deferred_non_nestable_work_queue_.pop();
+
+  RunTask(task.forget());
+  return true;
+}
+
+//------------------------------------------------------------------------------
+
+void MessageLoop::Quit() {
+  DCHECK(current() == this);
+  if (state_) {
+    state_->quit_received = true;
+  } else {
+    NOTREACHED() << "Must be inside Run to call Quit";
+  }
+}
+
+void MessageLoop::PostTask(already_AddRefed<nsIRunnable> task) {
+  PostTask_Helper(std::move(task), 0);
+}
+
+void MessageLoop::PostDelayedTask(already_AddRefed<nsIRunnable> task,
+                                  int delay_ms) {
+  PostTask_Helper(std::move(task), delay_ms);
+}
+
+void MessageLoop::PostIdleTask(already_AddRefed<nsIRunnable> task) {
+  DCHECK(current() == this);
+  MOZ_ASSERT(NS_IsMainThread());
+
+  PendingTask pending_task(std::move(task), false);
+  mozilla::LogRunnable::LogDispatch(pending_task.task.get());
+  deferred_non_nestable_work_queue_.push(std::move(pending_task));
+}
+
+// Possibly called on a background thread!
+void MessageLoop::PostTask_Helper(already_AddRefed<nsIRunnable> task,
+                                  int delay_ms) {
+  if (nsISerialEventTarget* target = pump_->GetXPCOMThread()) {
+    nsresult rv;
+    if (delay_ms) {
+      rv = target->DelayedDispatch(std::move(task), delay_ms);
+    } else {
+      rv = target->Dispatch(std::move(task), 0);
+    }
+    MOZ_ALWAYS_SUCCEEDS(rv);
+    return;
+  }
+
+  // Tasks should only be queued before or during the Run loop, not after.
+  MOZ_ASSERT(!shutting_down_);
+
+  PendingTask pending_task(std::move(task), true);
+
+  if (delay_ms > 0) {
+    pending_task.delayed_run_time =
+        TimeTicks::Now() + TimeDelta::FromMilliseconds(delay_ms);
+  } else {
+    DCHECK(delay_ms == 0) << "delay should not be negative";
+  }
+
+  // Warning: Don't try to short-circuit, and handle this thread's tasks more
+  // directly, as it could starve handling of foreign threads.  Put every task
+  // into this queue.
+
+  RefPtr<base::MessagePump> pump;
+  {
+    mozilla::MutexAutoLock locked(incoming_queue_lock_);
+    mozilla::LogRunnable::LogDispatch(pending_task.task.get());
+    incoming_queue_.push(std::move(pending_task));
+    pump = pump_;
+  }
+  // Since the incoming_queue_ may contain a task that destroys this message
+  // loop, we cannot exit incoming_queue_lock_ until we are done with |this|.
+  // We use a stack-based reference to the message pump so that we can call
+  // ScheduleWork outside of incoming_queue_lock_.
+
+  pump->ScheduleWork();
+}
+
+void MessageLoop::SetNestableTasksAllowed(bool allowed) {
+  if (nestable_tasks_allowed_ != allowed) {
+    nestable_tasks_allowed_ = allowed;
+    if (!nestable_tasks_allowed_) return;
+    // Start the native pump if we are not already pumping.
+    pump_->ScheduleWorkForNestedLoop();
+  }
+}
+
+void MessageLoop::ScheduleWork() {
+  // Start the native pump if we are not already pumping.
+  pump_->ScheduleWork();
+}
+
+bool MessageLoop::NestableTasksAllowed() const {
+  return nestable_tasks_allowed_;
+}
+
+//------------------------------------------------------------------------------
+
+void MessageLoop::RunTask(already_AddRefed<nsIRunnable> aTask) {
+  DCHECK(nestable_tasks_allowed_);
+  // Execute the task and assume the worst: It is probably not reentrant.
+  nestable_tasks_allowed_ = false;
+
+  nsCOMPtr<nsIRunnable> task = aTask;
+
+  {
+    mozilla::LogRunnable::Run log(task.get());
+    AUTO_PROFILE_FOLLOWING_RUNNABLE(task);
+    task->Run();
+    task = nullptr;
+  }
+
+  nestable_tasks_allowed_ = true;
+}
+
+bool MessageLoop::DeferOrRunPendingTask(PendingTask&& pending_task) {
+  if (pending_task.nestable || state_->run_depth <= run_depth_base_) {
+    RunTask(pending_task.task.forget());
+    // Show that we ran a task (Note: a new one might arrive as a
+    // consequence!).
+    return true;
+  }
+
+  // We couldn't run the task now because we're in a nested message loop
+  // and the task isn't nestable.
+  mozilla::LogRunnable::LogDispatch(pending_task.task.get());
+  deferred_non_nestable_work_queue_.push(std::move(pending_task));
+  return false;
+}
+
+void MessageLoop::AddToDelayedWorkQueue(const PendingTask& pending_task) {
+  // Move to the delayed work queue.  Initialize the sequence number
+  // before inserting into the delayed_work_queue_.  The sequence number
+  // is used to faciliate FIFO sorting when two tasks have the same
+  // delayed_run_time value.
+  PendingTask new_pending_task(pending_task);
+  new_pending_task.sequence_num = next_sequence_num_++;
+  mozilla::LogRunnable::LogDispatch(new_pending_task.task.get());
+  delayed_work_queue_.push(std::move(new_pending_task));
+}
+
+void MessageLoop::ReloadWorkQueue() {
+  // We can improve performance of our loading tasks from incoming_queue_ to
+  // work_queue_ by waiting until the last minute (work_queue_ is empty) to
+  // load.  That reduces the number of locks-per-task significantly when our
+  // queues get large.
+  if (!work_queue_.empty())
+    return;  // Wait till we *really* need to lock and load.
+
+  // Acquire all we can from the inter-thread queue with one lock acquisition.
+  {
+    mozilla::MutexAutoLock lock(incoming_queue_lock_);
+    if (incoming_queue_.empty()) return;
+    std::swap(incoming_queue_, work_queue_);
+    DCHECK(incoming_queue_.empty());
+  }
+}
+
+bool MessageLoop::DeletePendingTasks() {
+  MOZ_ASSERT(work_queue_.empty());
+  bool did_work = !deferred_non_nestable_work_queue_.empty();
+  while (!deferred_non_nestable_work_queue_.empty()) {
+    deferred_non_nestable_work_queue_.pop();
+  }
+  did_work |= !delayed_work_queue_.empty();
+  while (!delayed_work_queue_.empty()) {
+    delayed_work_queue_.pop();
+  }
+  return did_work;
+}
+
+bool MessageLoop::DoWork() {
+  if (!nestable_tasks_allowed_) {
+    // Task can't be executed right now.
+    return false;
+  }
+
+  for (;;) {
+    ReloadWorkQueue();
+    if (work_queue_.empty()) break;
+
+    // Execute oldest task.
+    do {
+      PendingTask pending_task = std::move(work_queue_.front());
+      work_queue_.pop();
+      if (!pending_task.delayed_run_time.is_null()) {
+        // NB: Don't move, because we use this later!
+        AddToDelayedWorkQueue(pending_task);
+        // If we changed the topmost task, then it is time to re-schedule.
+        if (delayed_work_queue_.top().task == pending_task.task)
+          pump_->ScheduleDelayedWork(pending_task.delayed_run_time);
+      } else {
+        if (DeferOrRunPendingTask(std::move(pending_task))) return true;
+      }
+    } while (!work_queue_.empty());
+  }
+
+  // Nothing happened.
+  return false;
+}
+
+bool MessageLoop::DoDelayedWork(TimeTicks* next_delayed_work_time) {
+  if (!nestable_tasks_allowed_ || delayed_work_queue_.empty()) {
+    *next_delayed_work_time = TimeTicks();
+    return false;
+  }
+
+  if (delayed_work_queue_.top().delayed_run_time > TimeTicks::Now()) {
+    *next_delayed_work_time = delayed_work_queue_.top().delayed_run_time;
+    return false;
+  }
+
+  PendingTask pending_task = delayed_work_queue_.top();
+  delayed_work_queue_.pop();
+
+  if (!delayed_work_queue_.empty())
+    *next_delayed_work_time = delayed_work_queue_.top().delayed_run_time;
+
+  return DeferOrRunPendingTask(std::move(pending_task));
+}
+
+bool MessageLoop::DoIdleWork() {
+  if (ProcessNextDelayedNonNestableTask()) return true;
+
+  if (state_->quit_received) pump_->Quit();
+
+  return false;
+}
+
+//------------------------------------------------------------------------------
+// MessageLoop::AutoRunState
+
+MessageLoop::AutoRunState::AutoRunState(MessageLoop* loop) : loop_(loop) {
+  // Top-level Run should only get called once.
+  MOZ_ASSERT(!loop_->shutting_down_);
+
+  // Make the loop reference us.
+  previous_state_ = loop_->state_;
+  if (previous_state_) {
+    run_depth = previous_state_->run_depth + 1;
+  } else {
+    run_depth = 1;
+  }
+  loop_->state_ = this;
+
+  // Initialize the other fields:
+  quit_received = false;
+#if defined(XP_WIN)
+  dispatcher = NULL;
+#endif
+}
+
+MessageLoop::AutoRunState::~AutoRunState() {
+  loop_->state_ = previous_state_;
+
+  // If exiting a top-level Run, then we're shutting down.
+  loop_->shutting_down_ = !previous_state_;
+}
+
+//------------------------------------------------------------------------------
+// MessageLoop::PendingTask
+
+bool MessageLoop::PendingTask::operator<(const PendingTask& other) const {
+  // Since the top of a priority queue is defined as the "greatest" element, we
+  // need to invert the comparison here.  We want the smaller time to be at the
+  // top of the heap.
+
+  if (delayed_run_time < other.delayed_run_time) return false;
+
+  if (delayed_run_time > other.delayed_run_time) return true;
+
+  // If the times happen to match, then we use the sequence number to decide.
+  // Compare the difference to support integer roll-over.
+  return (sequence_num - other.sequence_num) > 0;
+}
+
+//------------------------------------------------------------------------------
+// MessageLoop::SerialEventTarget
+
+nsISerialEventTarget* MessageLoop::SerialEventTarget() { return mEventTarget; }
+
+//------------------------------------------------------------------------------
+// MessageLoopForUI
+
+#if defined(XP_WIN)
+
+void MessageLoopForUI::Run(Dispatcher* dispatcher) {
+  AutoRunState save_state(this);
+  state_->dispatcher = dispatcher;
+  RunHandler();
+}
+
+void MessageLoopForUI::AddObserver(Observer* observer) {
+  pump_win()->AddObserver(observer);
+}
+
+void MessageLoopForUI::RemoveObserver(Observer* observer) {
+  pump_win()->RemoveObserver(observer);
+}
+
+void MessageLoopForUI::WillProcessMessage(const MSG& message) {
+  pump_win()->WillProcessMessage(message);
+}
+void MessageLoopForUI::DidProcessMessage(const MSG& message) {
+  pump_win()->DidProcessMessage(message);
+}
+void MessageLoopForUI::PumpOutPendingPaintMessages() {
+  pump_ui()->PumpOutPendingPaintMessages();
+}
+
+#endif  // defined(XP_WIN)
+
+//------------------------------------------------------------------------------
+// MessageLoopForIO
+
+#if defined(XP_WIN)
+
+void MessageLoopForIO::RegisterIOHandler(HANDLE file, IOHandler* handler) {
+  pump_io()->RegisterIOHandler(file, handler);
+}
+
+bool MessageLoopForIO::WaitForIOCompletion(DWORD timeout, IOHandler* filter) {
+  return pump_io()->WaitForIOCompletion(timeout, filter);
+}
+
+#else
+
+bool MessageLoopForIO::WatchFileDescriptor(int fd, bool persistent, Mode mode,
+                                           FileDescriptorWatcher* controller,
+                                           Watcher* delegate) {
+  return pump_libevent()->WatchFileDescriptor(
+      fd, persistent, static_cast<base::MessagePumpLibevent::Mode>(mode),
+      controller, delegate);
+}
+
+bool MessageLoopForIO::CatchSignal(int sig, SignalEvent* sigevent,
+                                   SignalWatcher* delegate) {
+  return pump_libevent()->CatchSignal(sig, sigevent, delegate);
+}
+
+#endif