Adding upstream version 115.7.0esr.upstream/115.7.0esr

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

62 files changed, 12701 insertions, 0 deletions

diff --git a/netwerk/ipc/ChannelEventQueue.cpp b/netwerk/ipc/ChannelEventQueue.cpp
new file mode 100644
index 0000000000..911deaa7d9
--- /dev/null
+++ b/netwerk/ipc/ChannelEventQueue.cpp
@@ -0,0 +1,227 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set sw=2 ts=8 et tw=80 :
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ChannelEventQueue.h"
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Unused.h"
+#include "nsIChannel.h"
+#include "mozilla/dom/Document.h"
+#include "nsThreadUtils.h"
+
+namespace mozilla {
+namespace net {
+
+ChannelEvent* ChannelEventQueue::TakeEvent() {
+  mMutex.AssertCurrentThreadOwns();
+  MOZ_ASSERT(mFlushing);
+
+  if (mSuspended || mEventQueue.IsEmpty()) {
+    return nullptr;
+  }
+
+  UniquePtr<ChannelEvent> event(std::move(mEventQueue[0]));
+  mEventQueue.RemoveElementAt(0);
+
+  return event.release();
+}
+
+void ChannelEventQueue::FlushQueue() {
+  // Events flushed could include destruction of channel (and our own
+  // destructor) unless we make sure its refcount doesn't drop to 0 while this
+  // method is running.
+  nsCOMPtr<nsISupports> kungFuDeathGrip;
+  {
+    MutexAutoLock lock(mMutex);
+    kungFuDeathGrip = mOwner;
+  }
+  mozilla::Unused << kungFuDeathGrip;  // Not used in this function
+
+#ifdef DEBUG
+  {
+    MutexAutoLock lock(mMutex);
+    MOZ_ASSERT(mFlushing);
+  }
+#endif  // DEBUG
+
+  bool needResumeOnOtherThread = false;
+
+  while (true) {
+    UniquePtr<ChannelEvent> event;
+    {
+      MutexAutoLock lock(mMutex);
+      event.reset(TakeEvent());
+      if (!event) {
+        MOZ_ASSERT(mFlushing);
+        mFlushing = false;
+        MOZ_ASSERT(mEventQueue.IsEmpty() || (mSuspended || !!mForcedCount));
+        break;
+      }
+    }
+
+    nsCOMPtr<nsIEventTarget> target = event->GetEventTarget();
+    MOZ_ASSERT(target);
+
+    bool isCurrentThread = false;
+    nsresult rv = target->IsOnCurrentThread(&isCurrentThread);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      // Simply run this event on current thread if we are not sure about it
+      // in release channel, or assert in Aurora/Nightly channel.
+      MOZ_DIAGNOSTIC_ASSERT(false);
+      isCurrentThread = true;
+    }
+
+    if (!isCurrentThread) {
+      // Next event needs to run on another thread. Put it back to
+      // the front of the queue can try resume on that thread.
+      Suspend();
+      PrependEvent(std::move(event));
+
+      needResumeOnOtherThread = true;
+      {
+        MutexAutoLock lock(mMutex);
+        MOZ_ASSERT(mFlushing);
+        mFlushing = false;
+        MOZ_ASSERT(!mEventQueue.IsEmpty());
+      }
+      break;
+    }
+
+    event->Run();
+  }  // end of while(true)
+
+  // The flush procedure is aborted because next event cannot be run on current
+  // thread. We need to resume the event processing right after flush procedure
+  // is finished.
+  // Note: we cannot call Resume() while "mFlushing == true" because
+  // CompleteResume will not trigger FlushQueue while there is an ongoing flush.
+  if (needResumeOnOtherThread) {
+    Resume();
+  }
+}
+
+void ChannelEventQueue::Suspend() {
+  MutexAutoLock lock(mMutex);
+  SuspendInternal();
+}
+
+void ChannelEventQueue::SuspendInternal() {
+  mMutex.AssertCurrentThreadOwns();
+
+  mSuspended = true;
+  mSuspendCount++;
+}
+
+void ChannelEventQueue::Resume() {
+  MutexAutoLock lock(mMutex);
+  ResumeInternal();
+}
+
+void ChannelEventQueue::ResumeInternal() {
+  mMutex.AssertCurrentThreadOwns();
+
+  // Resuming w/o suspend: error in debug mode, ignore in build
+  MOZ_ASSERT(mSuspendCount > 0);
+  if (mSuspendCount <= 0) {
+    return;
+  }
+
+  if (!--mSuspendCount) {
+    if (mEventQueue.IsEmpty() || !!mForcedCount) {
+      // Nothing in queue to flush or waiting for AutoEventEnqueuer to
+      // finish the force enqueue period, simply clear the flag.
+      mSuspended = false;
+      return;
+    }
+
+    // Hold a strong reference of mOwner to avoid the channel release
+    // before CompleteResume was executed.
+    class CompleteResumeRunnable : public Runnable {
+     public:
+      explicit CompleteResumeRunnable(ChannelEventQueue* aQueue,
+                                      nsISupports* aOwner)
+          : Runnable("CompleteResumeRunnable"),
+            mQueue(aQueue),
+            mOwner(aOwner) {}
+
+      NS_IMETHOD Run() override {
+        mQueue->CompleteResume();
+        return NS_OK;
+      }
+
+     private:
+      virtual ~CompleteResumeRunnable() = default;
+
+      RefPtr<ChannelEventQueue> mQueue;
+      nsCOMPtr<nsISupports> mOwner;
+    };
+
+    if (!mOwner) {
+      return;
+    }
+
+    // Worker thread requires a CancelableRunnable.
+    RefPtr<Runnable> event = new CompleteResumeRunnable(this, mOwner);
+
+    nsCOMPtr<nsIEventTarget> target;
+    target = mEventQueue[0]->GetEventTarget();
+    MOZ_ASSERT(target);
+
+    Unused << NS_WARN_IF(
+        NS_FAILED(target->Dispatch(event.forget(), NS_DISPATCH_NORMAL)));
+  }
+}
+
+bool ChannelEventQueue::MaybeSuspendIfEventsAreSuppressed() {
+  // We only ever need to suppress events on the main thread, since this is
+  // where content scripts can run.
+  if (!NS_IsMainThread()) {
+    return false;
+  }
+
+  // Only suppress events for queues associated with XHRs, as these can cause
+  // content scripts to run.
+  if (mHasCheckedForXMLHttpRequest && !mForXMLHttpRequest) {
+    return false;
+  }
+
+  mMutex.AssertCurrentThreadOwns();
+  nsCOMPtr<nsIChannel> channel(do_QueryInterface(mOwner));
+  if (!channel) {
+    return false;
+  }
+
+  nsCOMPtr<nsILoadInfo> loadInfo = channel->LoadInfo();
+  // Figure out if this is for an XHR, if we haven't done so already.
+  if (!mHasCheckedForXMLHttpRequest) {
+    nsContentPolicyType contentType = loadInfo->InternalContentPolicyType();
+    mForXMLHttpRequest =
+        (contentType == nsIContentPolicy::TYPE_INTERNAL_XMLHTTPREQUEST);
+    mHasCheckedForXMLHttpRequest = true;
+
+    if (!mForXMLHttpRequest) {
+      return false;
+    }
+  }
+
+  // Suspend the queue if the associated document has suppressed event handling,
+  // *and* it is not in the middle of a synchronous operation that might require
+  // XHR events to be processed (such as a synchronous XHR).
+  RefPtr<dom::Document> document;
+  loadInfo->GetLoadingDocument(getter_AddRefs(document));
+  if (document && document->EventHandlingSuppressed() &&
+      !document->IsInSyncOperation()) {
+    document->AddSuspendedChannelEventQueue(this);
+    SuspendInternal();
+    return true;
+  }
+
+  return false;
+}
+
+}  // namespace net
+}  // namespace mozilla
diff --git a/netwerk/ipc/ChannelEventQueue.h b/netwerk/ipc/ChannelEventQueue.h
new file mode 100644
index 0000000000..b6f16c86fa
--- /dev/null
+++ b/netwerk/ipc/ChannelEventQueue.h
@@ -0,0 +1,366 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set sw=2 ts=8 et tw=80 :
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_ChannelEventQueue_h
+#define mozilla_net_ChannelEventQueue_h
+
+#include "nsTArray.h"
+#include "nsIEventTarget.h"
+#include "nsThreadUtils.h"
+#include "nsXULAppAPI.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/RecursiveMutex.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/Unused.h"
+
+class nsISupports;
+
+namespace mozilla {
+namespace net {
+
+class ChannelEvent {
+ public:
+  MOZ_COUNTED_DEFAULT_CTOR(ChannelEvent)
+  MOZ_COUNTED_DTOR_VIRTUAL(ChannelEvent) virtual void Run() = 0;
+  virtual already_AddRefed<nsIEventTarget> GetEventTarget() = 0;
+};
+
+// Note that MainThreadChannelEvent should not be used in child process since
+// GetEventTarget() directly returns an unlabeled event target.
+class MainThreadChannelEvent : public ChannelEvent {
+ public:
+  MOZ_COUNTED_DEFAULT_CTOR(MainThreadChannelEvent)
+  MOZ_COUNTED_DTOR_OVERRIDE(MainThreadChannelEvent)
+
+  already_AddRefed<nsIEventTarget> GetEventTarget() override {
+    MOZ_ASSERT(XRE_IsParentProcess());
+
+    return do_AddRef(GetMainThreadSerialEventTarget());
+  }
+};
+
+class ChannelFunctionEvent : public ChannelEvent {
+ public:
+  ChannelFunctionEvent(
+      std::function<already_AddRefed<nsIEventTarget>()>&& aGetEventTarget,
+      std::function<void()>&& aCallback)
+      : mGetEventTarget(std::move(aGetEventTarget)),
+        mCallback(std::move(aCallback)) {}
+
+  void Run() override { mCallback(); }
+  already_AddRefed<nsIEventTarget> GetEventTarget() override {
+    return mGetEventTarget();
+  }
+
+ private:
+  const std::function<already_AddRefed<nsIEventTarget>()> mGetEventTarget;
+  const std::function<void()> mCallback;
+};
+
+// UnsafePtr is a work-around our static analyzer that requires all
+// ref-counted objects to be captured in lambda via a RefPtr
+// The ChannelEventQueue makes it safe to capture "this" by pointer only.
+// This is required as work-around to prevent cycles until bug 1596295
+// is resolved.
+template <typename T>
+class UnsafePtr {
+ public:
+  explicit UnsafePtr(T* aPtr) : mPtr(aPtr) {}
+
+  T& operator*() const { return *mPtr; }
+  T* operator->() const {
+    MOZ_ASSERT(mPtr, "dereferencing a null pointer");
+    return mPtr;
+  }
+  operator T*() const& { return mPtr; }
+  explicit operator bool() const { return mPtr != nullptr; }
+
+ private:
+  T* const mPtr;
+};
+
+class NeckoTargetChannelFunctionEvent : public ChannelFunctionEvent {
+ public:
+  template <typename T>
+  NeckoTargetChannelFunctionEvent(T* aChild, std::function<void()>&& aCallback)
+      : ChannelFunctionEvent(
+            [child = UnsafePtr<T>(aChild)]() {
+              MOZ_ASSERT(child);
+              return child->GetNeckoTarget();
+            },
+            std::move(aCallback)) {}
+};
+
+// Workaround for Necko re-entrancy dangers. We buffer IPDL messages in a
+// queue if still dispatching previous one(s) to listeners/observers.
+// Otherwise synchronous XMLHttpRequests and/or other code that spins the
+// event loop (ex: IPDL rpc) could cause listener->OnDataAvailable (for
+// instance) to be dispatched and called before mListener->OnStartRequest has
+// completed.
+
+class ChannelEventQueue final {
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ChannelEventQueue)
+
+ public:
+  explicit ChannelEventQueue(nsISupports* owner)
+      : mSuspendCount(0),
+        mSuspended(false),
+        mForcedCount(0),
+        mFlushing(false),
+        mHasCheckedForXMLHttpRequest(false),
+        mForXMLHttpRequest(false),
+        mOwner(owner),
+        mMutex("ChannelEventQueue::mMutex"),
+        mRunningMutex("ChannelEventQueue::mRunningMutex") {}
+
+  // Puts IPDL-generated channel event into queue, to be run later
+  // automatically when EndForcedQueueing and/or Resume is called.
+  //
+  // @param aCallback - the ChannelEvent
+  // @param aAssertionWhenNotQueued - this optional param will be used in an
+  //   assertion when the event is executed directly.
+  inline void RunOrEnqueue(ChannelEvent* aCallback,
+                           bool aAssertionWhenNotQueued = false);
+
+  // Append ChannelEvent in front of the event queue.
+  inline void PrependEvent(UniquePtr<ChannelEvent>&& aEvent);
+  inline void PrependEvents(nsTArray<UniquePtr<ChannelEvent>>& aEvents);
+
+  // After StartForcedQueueing is called, RunOrEnqueue() will start enqueuing
+  // events that will be run/flushed when EndForcedQueueing is called.
+  // - Note: queueing may still be required after EndForcedQueueing() (if the
+  //   queue is suspended, etc):  always call RunOrEnqueue() to avoid race
+  //   conditions.
+  inline void StartForcedQueueing();
+  inline void EndForcedQueueing();
+
+  // Suspend/resume event queue.  RunOrEnqueue() will start enqueuing
+  // events and they will be run/flushed when resume is called.  These should be
+  // called when the channel owning the event queue is suspended/resumed.
+  void Suspend();
+  // Resume flushes the queue asynchronously, i.e. items in queue will be
+  // dispatched in a new event on the current thread.
+  void Resume();
+
+  void NotifyReleasingOwner() {
+    MutexAutoLock lock(mMutex);
+    mOwner = nullptr;
+  }
+
+#ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
+  bool IsEmpty() {
+    MutexAutoLock lock(mMutex);
+    return mEventQueue.IsEmpty();
+  }
+#endif
+
+ private:
+  // Private destructor, to discourage deletion outside of Release():
+  ~ChannelEventQueue() = default;
+
+  void SuspendInternal();
+  void ResumeInternal();
+
+  bool MaybeSuspendIfEventsAreSuppressed() MOZ_REQUIRES(mMutex);
+
+  inline void MaybeFlushQueue();
+  void FlushQueue();
+  inline void CompleteResume();
+
+  ChannelEvent* TakeEvent();
+
+  nsTArray<UniquePtr<ChannelEvent>> mEventQueue MOZ_GUARDED_BY(mMutex);
+
+  uint32_t mSuspendCount MOZ_GUARDED_BY(mMutex);
+  bool mSuspended MOZ_GUARDED_BY(mMutex);
+  uint32_t mForcedCount  // Support ForcedQueueing on multiple thread.
+      MOZ_GUARDED_BY(mMutex);
+  bool mFlushing MOZ_GUARDED_BY(mMutex);
+
+  // Whether the queue is associated with an XHR. This is lazily instantiated
+  // the first time it is needed. These are MainThread-only.
+  bool mHasCheckedForXMLHttpRequest;
+  bool mForXMLHttpRequest;
+
+  // Keep ptr to avoid refcount cycle: only grab ref during flushing.
+  nsISupports* mOwner MOZ_GUARDED_BY(mMutex);
+
+  // For atomic mEventQueue operation and state update
+  Mutex mMutex;
+
+  // To guarantee event execution order among threads
+  RecursiveMutex mRunningMutex MOZ_ACQUIRED_BEFORE(mMutex);
+
+  friend class AutoEventEnqueuer;
+};
+
+inline void ChannelEventQueue::RunOrEnqueue(ChannelEvent* aCallback,
+                                            bool aAssertionWhenNotQueued) {
+  MOZ_ASSERT(aCallback);
+  // Events execution could be a destruction of the channel (and our own
+  // destructor) unless we make sure its refcount doesn't drop to 0 while this
+  // method is running.
+  nsCOMPtr<nsISupports> kungFuDeathGrip;
+
+  // To avoid leaks.
+  UniquePtr<ChannelEvent> event(aCallback);
+
+  // To guarantee that the running event and all the events generated within
+  // it will be finished before events on other threads.
+  RecursiveMutexAutoLock lock(mRunningMutex);
+  {
+    MutexAutoLock lock(mMutex);
+    kungFuDeathGrip = mOwner;  // must be under the lock
+
+    bool enqueue = !!mForcedCount || mSuspended || mFlushing ||
+                   !mEventQueue.IsEmpty() ||
+                   MaybeSuspendIfEventsAreSuppressed();
+
+    if (enqueue) {
+      mEventQueue.AppendElement(std::move(event));
+      return;
+    }
+
+    nsCOMPtr<nsIEventTarget> target = event->GetEventTarget();
+    MOZ_ASSERT(target);
+
+    bool isCurrentThread = false;
+    DebugOnly<nsresult> rv = target->IsOnCurrentThread(&isCurrentThread);
+    MOZ_ASSERT(NS_SUCCEEDED(rv));
+
+    if (!isCurrentThread) {
+      // Leverage Suspend/Resume mechanism to trigger flush procedure without
+      // creating a new one.
+      SuspendInternal();
+      mEventQueue.AppendElement(std::move(event));
+      ResumeInternal();
+      return;
+    }
+  }
+
+  MOZ_RELEASE_ASSERT(!aAssertionWhenNotQueued);
+  event->Run();
+}
+
+inline void ChannelEventQueue::StartForcedQueueing() {
+  MutexAutoLock lock(mMutex);
+  ++mForcedCount;
+}
+
+inline void ChannelEventQueue::EndForcedQueueing() {
+  bool tryFlush = false;
+  {
+    MutexAutoLock lock(mMutex);
+    MOZ_ASSERT(mForcedCount > 0);
+    if (!--mForcedCount) {
+      tryFlush = true;
+    }
+  }
+
+  if (tryFlush) {
+    MaybeFlushQueue();
+  }
+}
+
+inline void ChannelEventQueue::PrependEvent(UniquePtr<ChannelEvent>&& aEvent) {
+  MutexAutoLock lock(mMutex);
+
+  // Prepending event while no queue flush foreseen might cause the following
+  // channel events not run. This assertion here guarantee there must be a
+  // queue flush, either triggered by Resume or EndForcedQueueing, to execute
+  // the added event.
+  MOZ_ASSERT(mSuspended || !!mForcedCount);
+
+  mEventQueue.InsertElementAt(0, std::move(aEvent));
+}
+
+inline void ChannelEventQueue::PrependEvents(
+    nsTArray<UniquePtr<ChannelEvent>>& aEvents) {
+  MutexAutoLock lock(mMutex);
+
+  // Prepending event while no queue flush foreseen might cause the following
+  // channel events not run. This assertion here guarantee there must be a
+  // queue flush, either triggered by Resume or EndForcedQueueing, to execute
+  // the added events.
+  MOZ_ASSERT(mSuspended || !!mForcedCount);
+
+  mEventQueue.InsertElementsAt(0, aEvents.Length());
+
+  for (uint32_t i = 0; i < aEvents.Length(); i++) {
+    mEventQueue[i] = std::move(aEvents[i]);
+  }
+}
+
+inline void ChannelEventQueue::CompleteResume() {
+  bool tryFlush = false;
+  {
+    MutexAutoLock lock(mMutex);
+
+    // channel may have been suspended again since Resume fired event to call
+    // this.
+    if (!mSuspendCount) {
+      // we need to remain logically suspended (for purposes of queuing incoming
+      // messages) until this point, else new incoming messages could run before
+      // queued ones.
+      mSuspended = false;
+      tryFlush = true;
+    }
+  }
+
+  if (tryFlush) {
+    MaybeFlushQueue();
+  }
+}
+
+inline void ChannelEventQueue::MaybeFlushQueue() {
+  // Don't flush if forced queuing on, we're already being flushed, or
+  // suspended, or there's nothing to flush
+  bool flushQueue = false;
+
+  {
+    MutexAutoLock lock(mMutex);
+    flushQueue = !mForcedCount && !mFlushing && !mSuspended &&
+                 !mEventQueue.IsEmpty() && !MaybeSuspendIfEventsAreSuppressed();
+
+    // Only one thread is allowed to run FlushQueue at a time.
+    if (flushQueue) {
+      mFlushing = true;
+    }
+  }
+
+  if (flushQueue) {
+    FlushQueue();
+  }
+}
+
+// Ensures that RunOrEnqueue() will be collecting events during its lifetime
+// (letting caller know incoming IPDL msgs should be queued). Flushes the queue
+// when it goes out of scope.
+class MOZ_STACK_CLASS AutoEventEnqueuer {
+ public:
+  explicit AutoEventEnqueuer(ChannelEventQueue* queue) : mEventQueue(queue) {
+    {
+      // Probably not actually needed, since NotifyReleasingOwner should
+      // only happen after this, but safer to take it in case things change
+      MutexAutoLock lock(queue->mMutex);
+      mOwner = queue->mOwner;
+    }
+    mEventQueue->StartForcedQueueing();
+  }
+  ~AutoEventEnqueuer() { mEventQueue->EndForcedQueueing(); }
+
+ private:
+  RefPtr<ChannelEventQueue> mEventQueue;
+  // Ensure channel object lives longer than ChannelEventQueue.
+  nsCOMPtr<nsISupports> mOwner;
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif
diff --git a/netwerk/ipc/DocumentChannel.cpp b/netwerk/ipc/DocumentChannel.cpp
new file mode 100644
index 0000000000..767b615c26
--- /dev/null
+++ b/netwerk/ipc/DocumentChannel.cpp
@@ -0,0 +1,478 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/net/DocumentChannel.h"
+
+#include <inttypes.h>
+#include <utility>
+#include "mozIDOMWindow.h"
+#include "mozilla/AlreadyAddRefed.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/LoadInfo.h"
+#include "mozilla/Logging.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/Unused.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/net/DocumentChannelChild.h"
+#include "mozilla/net/ParentProcessDocumentChannel.h"
+#include "nsCOMPtr.h"
+#include "nsDebug.h"
+#include "nsDocShell.h"
+#include "nsDocShellLoadState.h"
+#include "nsHttpHandler.h"
+#include "nsIContentPolicy.h"
+#include "nsIInterfaceRequestor.h"
+#include "nsILoadContext.h"
+#include "nsILoadGroup.h"
+#include "nsILoadInfo.h"
+#include "nsIStreamListener.h"
+#include "nsIURI.h"
+#include "nsMimeTypes.h"
+#include "nsNetUtil.h"
+#include "nsPIDOMWindow.h"
+#include "nsPIDOMWindowInlines.h"
+#include "nsStringFwd.h"
+#include "nsThreadUtils.h"
+#include "nsXULAppAPI.h"
+#include "nscore.h"
+
+using namespace mozilla::dom;
+using namespace mozilla::ipc;
+
+extern mozilla::LazyLogModule gDocumentChannelLog;
+#define LOG(fmt) MOZ_LOG(gDocumentChannelLog, mozilla::LogLevel::Verbose, fmt)
+
+namespace mozilla {
+namespace net {
+
+//-----------------------------------------------------------------------------
+// DocumentChannel::nsISupports
+
+NS_IMPL_ADDREF(DocumentChannel)
+NS_IMPL_RELEASE(DocumentChannel)
+
+NS_INTERFACE_MAP_BEGIN(DocumentChannel)
+  NS_INTERFACE_MAP_ENTRY(nsIRequest)
+  NS_INTERFACE_MAP_ENTRY(nsIChannel)
+  NS_INTERFACE_MAP_ENTRY(nsIIdentChannel)
+  NS_INTERFACE_MAP_ENTRY_CONCRETE(DocumentChannel)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIRequest)
+NS_INTERFACE_MAP_END
+
+DocumentChannel::DocumentChannel(nsDocShellLoadState* aLoadState,
+                                 net::LoadInfo* aLoadInfo,
+                                 nsLoadFlags aLoadFlags, uint32_t aCacheKey,
+                                 bool aUriModified, bool aIsXFOError)
+    : mLoadState(aLoadState),
+      mCacheKey(aCacheKey),
+      mLoadFlags(aLoadFlags),
+      mURI(aLoadState->URI()),
+      mLoadInfo(aLoadInfo),
+      mUriModified(aUriModified),
+      mIsXFOError(aIsXFOError) {
+  LOG(("DocumentChannel ctor [this=%p, uri=%s]", this,
+       aLoadState->URI()->GetSpecOrDefault().get()));
+  RefPtr<nsHttpHandler> handler = nsHttpHandler::GetInstance();
+  uint64_t channelId;
+  Unused << handler->NewChannelId(channelId);
+  mChannelId = channelId;
+}
+
+NS_IMETHODIMP
+DocumentChannel::AsyncOpen(nsIStreamListener* aListener) {
+  MOZ_CRASH("If we get here, something is broken");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+void DocumentChannel::ShutdownListeners(nsresult aStatusCode) {
+  LOG(("DocumentChannel ShutdownListeners [this=%p, status=%" PRIx32 "]", this,
+       static_cast<uint32_t>(aStatusCode)));
+  mStatus = aStatusCode;
+
+  nsCOMPtr<nsIStreamListener> listener = mListener;
+  if (listener) {
+    listener->OnStartRequest(this);
+  }
+
+  mIsPending = false;
+
+  listener = mListener;  // it might have changed!
+  nsCOMPtr<nsILoadGroup> loadGroup = mLoadGroup;
+
+  mListener = nullptr;
+  mLoadGroup = nullptr;
+  mCallbacks = nullptr;
+
+  NS_DispatchToMainThread(NS_NewRunnableFunction(
+      "DocumentChannel::ShutdownListeners", [=, self = RefPtr{this}] {
+        if (listener) {
+          listener->OnStopRequest(self, aStatusCode);
+        }
+
+        if (loadGroup) {
+          loadGroup->RemoveRequest(self, nullptr, aStatusCode);
+        }
+      }));
+
+  DeleteIPDL();
+}
+
+void DocumentChannel::DisconnectChildListeners(
+    const nsresult& aStatus, const nsresult& aLoadGroupStatus) {
+  MOZ_ASSERT(NS_FAILED(aStatus));
+  mStatus = aLoadGroupStatus;
+  // Make sure we remove from the load group before
+  // setting mStatus, as existing tests expect the
+  // status to be successful when we disconnect.
+  if (mLoadGroup) {
+    mLoadGroup->RemoveRequest(this, nullptr, aStatus);
+    mLoadGroup = nullptr;
+  }
+
+  ShutdownListeners(aStatus);
+}
+
+nsDocShell* DocumentChannel::GetDocShell() {
+  nsCOMPtr<nsILoadContext> loadContext;
+  NS_QueryNotificationCallbacks(this, loadContext);
+  if (!loadContext) {
+    return nullptr;
+  }
+  nsCOMPtr<mozIDOMWindowProxy> domWindow;
+  loadContext->GetAssociatedWindow(getter_AddRefs(domWindow));
+  if (!domWindow) {
+    return nullptr;
+  }
+  auto* pDomWindow = nsPIDOMWindowOuter::From(domWindow);
+  nsIDocShell* docshell = pDomWindow->GetDocShell();
+  return nsDocShell::Cast(docshell);
+}
+
+static bool URIUsesDocChannel(nsIURI* aURI) {
+  if (SchemeIsJavascript(aURI)) {
+    return false;
+  }
+
+  nsCString spec = aURI->GetSpecOrDefault();
+  return !spec.EqualsLiteral("about:crashcontent");
+}
+
+bool DocumentChannel::CanUseDocumentChannel(nsIURI* aURI) {
+  // We want to use DocumentChannel if we're using a supported scheme.
+  return URIUsesDocChannel(aURI);
+}
+
+/* static */
+already_AddRefed<DocumentChannel> DocumentChannel::CreateForDocument(
+    nsDocShellLoadState* aLoadState, class LoadInfo* aLoadInfo,
+    nsLoadFlags aLoadFlags, nsIInterfaceRequestor* aNotificationCallbacks,
+    uint32_t aCacheKey, bool aUriModified, bool aIsXFOError) {
+  RefPtr<DocumentChannel> channel;
+  if (XRE_IsContentProcess()) {
+    channel = new DocumentChannelChild(aLoadState, aLoadInfo, aLoadFlags,
+                                       aCacheKey, aUriModified, aIsXFOError);
+  } else {
+    channel =
+        new ParentProcessDocumentChannel(aLoadState, aLoadInfo, aLoadFlags,
+                                         aCacheKey, aUriModified, aIsXFOError);
+  }
+  channel->SetNotificationCallbacks(aNotificationCallbacks);
+  return channel.forget();
+}
+
+/* static */
+already_AddRefed<DocumentChannel> DocumentChannel::CreateForObject(
+    nsDocShellLoadState* aLoadState, class LoadInfo* aLoadInfo,
+    nsLoadFlags aLoadFlags, nsIInterfaceRequestor* aNotificationCallbacks) {
+  return CreateForDocument(aLoadState, aLoadInfo, aLoadFlags,
+                           aNotificationCallbacks, 0, false, false);
+}
+
+NS_IMETHODIMP DocumentChannel::SetCanceledReason(const nsACString& aReason) {
+  return SetCanceledReasonImpl(aReason);
+}
+
+NS_IMETHODIMP DocumentChannel::GetCanceledReason(nsACString& aReason) {
+  return GetCanceledReasonImpl(aReason);
+}
+
+NS_IMETHODIMP DocumentChannel::CancelWithReason(nsresult aStatus,
+                                                const nsACString& aReason) {
+  return CancelWithReasonImpl(aStatus, aReason);
+}
+
+NS_IMETHODIMP
+DocumentChannel::Cancel(nsresult aStatusCode) {
+  MOZ_CRASH("If we get here, something is broken");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+DocumentChannel::Suspend() {
+  MOZ_CRASH("If we get here, something is broken");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+DocumentChannel::Resume() {
+  MOZ_CRASH("If we get here, something is broken");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+//-----------------------------------------------------------------------------
+// Remainder of nsIRequest/nsIChannel.
+//-----------------------------------------------------------------------------
+
+NS_IMETHODIMP DocumentChannel::GetNotificationCallbacks(
+    nsIInterfaceRequestor** aCallbacks) {
+  nsCOMPtr<nsIInterfaceRequestor> callbacks(mCallbacks);
+  callbacks.forget(aCallbacks);
+  return NS_OK;
+}
+
+NS_IMETHODIMP DocumentChannel::SetNotificationCallbacks(
+    nsIInterfaceRequestor* aNotificationCallbacks) {
+  mCallbacks = aNotificationCallbacks;
+  return NS_OK;
+}
+
+NS_IMETHODIMP DocumentChannel::GetLoadGroup(nsILoadGroup** aLoadGroup) {
+  nsCOMPtr<nsILoadGroup> loadGroup(mLoadGroup);
+  loadGroup.forget(aLoadGroup);
+  return NS_OK;
+}
+
+NS_IMETHODIMP DocumentChannel::SetLoadGroup(nsILoadGroup* aLoadGroup) {
+  mLoadGroup = aLoadGroup;
+  return NS_OK;
+}
+
+NS_IMETHODIMP DocumentChannel::GetStatus(nsresult* aStatus) {
+  *aStatus = mStatus;
+  return NS_OK;
+}
+
+NS_IMETHODIMP DocumentChannel::GetName(nsACString& aResult) {
+  if (!mURI) {
+    aResult.Truncate();
+    return NS_OK;
+  }
+  nsCString spec;
+  nsresult rv = mURI->GetSpec(spec);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  aResult.AssignLiteral("documentchannel:");
+  aResult.Append(spec);
+  return NS_OK;
+}
+
+NS_IMETHODIMP DocumentChannel::IsPending(bool* aResult) {
+  *aResult = mIsPending;
+  return NS_OK;
+}
+
+NS_IMETHODIMP DocumentChannel::GetLoadFlags(nsLoadFlags* aLoadFlags) {
+  *aLoadFlags = mLoadFlags;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+DocumentChannel::GetTRRMode(nsIRequest::TRRMode* aTRRMode) {
+  return GetTRRModeImpl(aTRRMode);
+}
+
+NS_IMETHODIMP
+DocumentChannel::SetTRRMode(nsIRequest::TRRMode aTRRMode) {
+  return SetTRRModeImpl(aTRRMode);
+}
+
+NS_IMETHODIMP DocumentChannel::SetLoadFlags(nsLoadFlags aLoadFlags) {
+  // Setting load flags for TYPE_OBJECT is OK, so long as the channel to parent
+  // isn't opened yet, or we're only setting the `LOAD_DOCUMENT_URI` flag.
+  auto contentPolicy = mLoadInfo->GetExternalContentPolicyType();
+  if (contentPolicy == ExtContentPolicy::TYPE_OBJECT) {
+    if (mWasOpened) {
+      MOZ_DIAGNOSTIC_ASSERT(
+          aLoadFlags == (mLoadFlags | nsIChannel::LOAD_DOCUMENT_URI),
+          "After the channel has been opened, can only set the "
+          "`LOAD_DOCUMENT_URI` flag.");
+    }
+    mLoadFlags = aLoadFlags;
+    return NS_OK;
+  }
+
+  MOZ_CRASH("DocumentChannel::SetLoadFlags: Don't set flags after creation");
+}
+
+NS_IMETHODIMP DocumentChannel::GetOriginalURI(nsIURI** aOriginalURI) {
+  nsCOMPtr<nsIURI> originalURI =
+      mLoadState->OriginalURI() ? mLoadState->OriginalURI() : mLoadState->URI();
+  originalURI.forget(aOriginalURI);
+  return NS_OK;
+}
+
+NS_IMETHODIMP DocumentChannel::SetOriginalURI(nsIURI* aOriginalURI) {
+  MOZ_CRASH("If we get here, something is broken");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP DocumentChannel::GetURI(nsIURI** aURI) {
+  nsCOMPtr<nsIURI> uri(mURI);
+  uri.forget(aURI);
+  return NS_OK;
+}
+
+NS_IMETHODIMP DocumentChannel::GetOwner(nsISupports** aOwner) {
+  nsCOMPtr<nsISupports> owner(mOwner);
+  owner.forget(aOwner);
+  return NS_OK;
+}
+
+NS_IMETHODIMP DocumentChannel::SetOwner(nsISupports* aOwner) {
+  mOwner = aOwner;
+  return NS_OK;
+}
+
+NS_IMETHODIMP DocumentChannel::GetSecurityInfo(
+    nsITransportSecurityInfo** aSecurityInfo) {
+  *aSecurityInfo = nullptr;
+  return NS_OK;
+}
+
+NS_IMETHODIMP DocumentChannel::GetContentType(nsACString& aContentType) {
+  // We may be trying to load HTML object data, and have determined that we're
+  // going to be performing a document load. In that case, fake the "text/html"
+  // content type for nsObjectLoadingContent.
+  if ((mLoadFlags & nsIRequest::LOAD_HTML_OBJECT_DATA) &&
+      (mLoadFlags & nsIChannel::LOAD_DOCUMENT_URI)) {
+    aContentType = TEXT_HTML;
+    return NS_OK;
+  }
+
+  NS_ERROR("If we get here, something is broken");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP DocumentChannel::SetContentType(const nsACString& aContentType) {
+  MOZ_CRASH("If we get here, something is broken");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP DocumentChannel::GetContentCharset(nsACString& aContentCharset) {
+  MOZ_CRASH("If we get here, something is broken");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP DocumentChannel::SetContentCharset(
+    const nsACString& aContentCharset) {
+  MOZ_CRASH("If we get here, something is broken");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP DocumentChannel::GetContentLength(int64_t* aContentLength) {
+  MOZ_CRASH("If we get here, something is broken");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP DocumentChannel::SetContentLength(int64_t aContentLength) {
+  MOZ_CRASH("If we get here, something is broken");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP DocumentChannel::Open(nsIInputStream** aStream) {
+  MOZ_CRASH("If we get here, something is broken");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP DocumentChannel::GetContentDisposition(
+    uint32_t* aContentDisposition) {
+  MOZ_CRASH("If we get here, something is broken");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP DocumentChannel::SetContentDisposition(
+    uint32_t aContentDisposition) {
+  MOZ_CRASH("If we get here, something is broken");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP DocumentChannel::GetContentDispositionFilename(
+    nsAString& aContentDispositionFilename) {
+  MOZ_CRASH("If we get here, something will be broken");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP DocumentChannel::SetContentDispositionFilename(
+    const nsAString& aContentDispositionFilename) {
+  MOZ_CRASH("If we get here, something will be broken");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP DocumentChannel::GetContentDispositionHeader(
+    nsACString& aContentDispositionHeader) {
+  MOZ_CRASH("If we get here, something is broken");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP DocumentChannel::GetLoadInfo(nsILoadInfo** aLoadInfo) {
+  nsCOMPtr<nsILoadInfo> loadInfo(mLoadInfo);
+  loadInfo.forget(aLoadInfo);
+  return NS_OK;
+}
+
+NS_IMETHODIMP DocumentChannel::SetLoadInfo(nsILoadInfo* aLoadInfo) {
+  MOZ_CRASH("If we get here, something is broken");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP DocumentChannel::GetIsDocument(bool* aIsDocument) {
+  return NS_GetIsDocumentChannel(this, aIsDocument);
+}
+
+NS_IMETHODIMP DocumentChannel::GetCanceled(bool* aCanceled) {
+  *aCanceled = mCanceled;
+  return NS_OK;
+}
+
+//-----------------------------------------------------------------------------
+// nsIIdentChannel
+//-----------------------------------------------------------------------------
+
+NS_IMETHODIMP
+DocumentChannel::GetChannelId(uint64_t* aChannelId) {
+  *aChannelId = mChannelId;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+DocumentChannel::SetChannelId(uint64_t aChannelId) {
+  mChannelId = aChannelId;
+  return NS_OK;
+}
+
+//-----------------------------------------------------------------------------
+// Helpers
+//-----------------------------------------------------------------------------
+
+uint64_t InnerWindowIDForExtantDoc(nsDocShell* docShell) {
+  if (!docShell) {
+    return 0;
+  }
+
+  Document* doc = docShell->GetExtantDocument();
+  if (!doc) {
+    return 0;
+  }
+
+  return doc->InnerWindowID();
+}
+
+}  // namespace net
+}  // namespace mozilla
+
+#undef LOG
diff --git a/netwerk/ipc/DocumentChannel.h b/netwerk/ipc/DocumentChannel.h
new file mode 100644
index 0000000000..364ebf0db0
--- /dev/null
+++ b/netwerk/ipc/DocumentChannel.h
@@ -0,0 +1,119 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_DocumentChannel_h
+#define mozilla_net_DocumentChannel_h
+
+#include "mozilla/dom/ClientInfo.h"
+#include "mozilla/net/NeckoChannelParams.h"
+#include "nsDOMNavigationTiming.h"
+#include "nsIChannel.h"
+#include "nsIChildChannel.h"
+
+class nsDocShell;
+
+#define DOCUMENT_CHANNEL_IID                         \
+  {                                                  \
+    0x6977bc44, 0xb1db, 0x41b7, {                    \
+      0xb5, 0xc5, 0xe2, 0x13, 0x68, 0x22, 0xc9, 0x8f \
+    }                                                \
+  }
+
+namespace mozilla {
+namespace net {
+
+uint64_t InnerWindowIDForExtantDoc(nsDocShell* docShell);
+
+/**
+ * DocumentChannel is a protocol agnostic placeholder nsIChannel implementation
+ * that we use so that nsDocShell knows about a connecting load. It transfers
+ * all data into a DocumentLoadListener (running in the parent process), which
+ * will create the real channel for the connection, and decide which process to
+ * load the resulting document in. If the document is to be loaded in the
+ * current process, then we'll synthesize a redirect replacing this placeholder
+ * channel with the real one, otherwise the originating docshell will be removed
+ * during the process switch.
+ */
+class DocumentChannel : public nsIIdentChannel {
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIREQUEST
+  NS_DECL_NSICHANNEL
+  NS_DECL_NSIIDENTCHANNEL
+
+  NS_DECLARE_STATIC_IID_ACCESSOR(DOCUMENT_CHANNEL_IID)
+
+  void SetNavigationTiming(nsDOMNavigationTiming* aTiming) {
+    mTiming = aTiming;
+  }
+
+  void SetInitialClientInfo(const Maybe<dom::ClientInfo>& aInfo) {
+    mInitialClientInfo = aInfo;
+  }
+
+  void DisconnectChildListeners(const nsresult& aStatus,
+                                const nsresult& aLoadGroupStatus);
+
+  /**
+   * Will create the appropriate document channel:
+   * Either a DocumentChannelChild if called from the content process or
+   * a ParentProcessDocumentChannel if called from the parent process.
+   * This operation is infallible.
+   */
+  static already_AddRefed<DocumentChannel> CreateForDocument(
+      nsDocShellLoadState* aLoadState, class LoadInfo* aLoadInfo,
+      nsLoadFlags aLoadFlags, nsIInterfaceRequestor* aNotificationCallbacks,
+      uint32_t aCacheKey, bool aUriModified, bool aIsXFOError);
+  static already_AddRefed<DocumentChannel> CreateForObject(
+      nsDocShellLoadState* aLoadState, class LoadInfo* aLoadInfo,
+      nsLoadFlags aLoadFlags, nsIInterfaceRequestor* aNotificationCallbacks);
+
+  static bool CanUseDocumentChannel(nsIURI* aURI);
+
+ protected:
+  DocumentChannel(nsDocShellLoadState* aLoadState, class LoadInfo* aLoadInfo,
+                  nsLoadFlags aLoadFlags, uint32_t aCacheKey, bool aUriModified,
+                  bool aIsXFOError);
+
+  void ShutdownListeners(nsresult aStatusCode);
+  virtual void DeleteIPDL() {}
+
+  nsDocShell* GetDocShell();
+
+  virtual ~DocumentChannel() = default;
+
+  const RefPtr<nsDocShellLoadState> mLoadState;
+  const uint32_t mCacheKey;
+
+  nsresult mStatus = NS_OK;
+  bool mCanceled = false;
+  bool mIsPending = false;
+  bool mWasOpened = false;
+  uint64_t mChannelId;
+  uint32_t mLoadFlags = LOAD_NORMAL;
+  const nsCOMPtr<nsIURI> mURI;
+  nsCOMPtr<nsILoadGroup> mLoadGroup;
+  nsCOMPtr<nsILoadInfo> mLoadInfo;
+  nsCOMPtr<nsIInterfaceRequestor> mCallbacks;
+  nsCOMPtr<nsIStreamListener> mListener;
+  nsCOMPtr<nsISupports> mOwner;
+  RefPtr<nsDOMNavigationTiming> mTiming;
+  Maybe<dom::ClientInfo> mInitialClientInfo;
+  // mUriModified is true if we're doing a history load and the URI of the
+  // session history had been modified by pushState/replaceState.
+  bool mUriModified = false;
+  // mIsXFOError is true if we're handling a load error and the status of the
+  // failed channel is NS_ERROR_XFO_VIOLATION.
+  bool mIsXFOError = false;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(DocumentChannel, DOCUMENT_CHANNEL_IID)
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_net_DocumentChannel_h
diff --git a/netwerk/ipc/DocumentChannelChild.cpp b/netwerk/ipc/DocumentChannelChild.cpp
new file mode 100644
index 0000000000..d06a464c4b
--- /dev/null
+++ b/netwerk/ipc/DocumentChannelChild.cpp
@@ -0,0 +1,480 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "DocumentChannelChild.h"
+
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/RemoteType.h"
+#include "mozilla/extensions/StreamFilterParent.h"
+#include "mozilla/ipc/Endpoint.h"
+#include "mozilla/net/HttpBaseChannel.h"
+#include "mozilla/net/NeckoChild.h"
+#include "mozilla/ScopeExit.h"
+#include "mozilla/StaticPrefs_fission.h"
+#include "nsHashPropertyBag.h"
+#include "nsIHttpChannelInternal.h"
+#include "nsIObjectLoadingContent.h"
+#include "nsIXULRuntime.h"
+#include "nsIWritablePropertyBag.h"
+#include "nsFrameLoader.h"
+#include "nsFrameLoaderOwner.h"
+#include "nsQueryObject.h"
+#include "nsDocShellLoadState.h"
+
+using namespace mozilla::dom;
+using namespace mozilla::ipc;
+
+extern mozilla::LazyLogModule gDocumentChannelLog;
+#define LOG(fmt) MOZ_LOG(gDocumentChannelLog, mozilla::LogLevel::Verbose, fmt)
+
+namespace mozilla {
+namespace net {
+
+//-----------------------------------------------------------------------------
+// DocumentChannelChild::nsISupports
+
+NS_INTERFACE_MAP_BEGIN(DocumentChannelChild)
+  NS_INTERFACE_MAP_ENTRY(nsIAsyncVerifyRedirectCallback)
+NS_INTERFACE_MAP_END_INHERITING(DocumentChannel)
+
+NS_IMPL_ADDREF_INHERITED(DocumentChannelChild, DocumentChannel)
+NS_IMPL_RELEASE_INHERITED(DocumentChannelChild, DocumentChannel)
+
+DocumentChannelChild::DocumentChannelChild(nsDocShellLoadState* aLoadState,
+                                           net::LoadInfo* aLoadInfo,
+                                           nsLoadFlags aLoadFlags,
+                                           uint32_t aCacheKey,
+                                           bool aUriModified, bool aIsXFOError)
+    : DocumentChannel(aLoadState, aLoadInfo, aLoadFlags, aCacheKey,
+                      aUriModified, aIsXFOError) {
+  mLoadingContext = nullptr;
+  LOG(("DocumentChannelChild ctor [this=%p, uri=%s]", this,
+       aLoadState->URI()->GetSpecOrDefault().get()));
+}
+
+DocumentChannelChild::~DocumentChannelChild() {
+  LOG(("DocumentChannelChild dtor [this=%p]", this));
+}
+
+NS_IMETHODIMP
+DocumentChannelChild::AsyncOpen(nsIStreamListener* aListener) {
+  nsresult rv = NS_OK;
+
+  nsCOMPtr<nsIStreamListener> listener = aListener;
+
+  NS_ENSURE_TRUE(gNeckoChild, NS_ERROR_FAILURE);
+  NS_ENSURE_ARG_POINTER(listener);
+  NS_ENSURE_TRUE(!mIsPending, NS_ERROR_IN_PROGRESS);
+  NS_ENSURE_TRUE(!mWasOpened, NS_ERROR_ALREADY_OPENED);
+
+  // Port checked in parent, but duplicate here so we can return with error
+  // immediately, as we've done since before e10s.
+  rv = NS_CheckPortSafety(mURI);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  bool isNotDownload = mLoadState->FileName().IsVoid();
+
+  // If not a download, add ourselves to the load group
+  if (isNotDownload && mLoadGroup) {
+    // During this call, we can re-enter back into the DocumentChannelChild to
+    // call SetNavigationTiming.
+    mLoadGroup->AddRequest(this, nullptr);
+  }
+
+  if (mCanceled) {
+    // We may have been canceled already, either by on-modify-request
+    // listeners or by load group observers; in that case, don't create IPDL
+    // connection. See nsHttpChannel::AsyncOpen().
+    return mStatus;
+  }
+
+  gHttpHandler->OnOpeningDocumentRequest(this);
+
+  RefPtr<nsDocShell> docShell = GetDocShell();
+  if (!docShell) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // `loadingContext` is the BC that is initiating the resource load.
+  // For normal subdocument loads, the BC is the one that the subdoc will load
+  // into. For <object>/<embed> it's the embedder doc's BC.
+  RefPtr<BrowsingContext> loadingContext = docShell->GetBrowsingContext();
+  if (!loadingContext || loadingContext->IsDiscarded()) {
+    return NS_ERROR_FAILURE;
+  }
+  mLoadingContext = loadingContext;
+
+  Maybe<IPCClientInfo> ipcClientInfo;
+  if (mInitialClientInfo.isSome()) {
+    ipcClientInfo.emplace(mInitialClientInfo.ref().ToIPC());
+  }
+
+  DocumentChannelElementCreationArgs ipcElementCreationArgs;
+  switch (mLoadInfo->GetExternalContentPolicyType()) {
+    case ExtContentPolicy::TYPE_DOCUMENT:
+    case ExtContentPolicy::TYPE_SUBDOCUMENT: {
+      DocumentCreationArgs docArgs;
+      docArgs.uriModified() = mUriModified;
+      docArgs.isXFOError() = mIsXFOError;
+
+      ipcElementCreationArgs = docArgs;
+      break;
+    }
+
+    case ExtContentPolicy::TYPE_OBJECT: {
+      ObjectCreationArgs objectArgs;
+      objectArgs.embedderInnerWindowId() = InnerWindowIDForExtantDoc(docShell);
+      objectArgs.loadFlags() = mLoadFlags;
+      objectArgs.contentPolicyType() = mLoadInfo->InternalContentPolicyType();
+      objectArgs.isUrgentStart() = UserActivation::IsHandlingUserInput();
+
+      ipcElementCreationArgs = objectArgs;
+      break;
+    }
+
+    default:
+      MOZ_ASSERT_UNREACHABLE("unsupported content policy type");
+      return NS_ERROR_FAILURE;
+  }
+
+  switch (mLoadInfo->GetExternalContentPolicyType()) {
+    case ExtContentPolicy::TYPE_DOCUMENT:
+    case ExtContentPolicy::TYPE_SUBDOCUMENT:
+      MOZ_ALWAYS_SUCCEEDS(loadingContext->SetCurrentLoadIdentifier(
+          Some(mLoadState->GetLoadIdentifier())));
+      break;
+
+    default:
+      break;
+  }
+
+  DocumentChannelCreationArgs args(
+      mozilla::WrapNotNull(mLoadState), TimeStamp::Now(), mChannelId, mCacheKey,
+      mTiming, ipcClientInfo, ipcElementCreationArgs,
+      loadingContext->GetParentInitiatedNavigationEpoch());
+
+  gNeckoChild->SendPDocumentChannelConstructor(this, loadingContext, args);
+
+  mIsPending = true;
+  mWasOpened = true;
+  mListener = listener;
+
+  return NS_OK;
+}
+
+IPCResult DocumentChannelChild::RecvFailedAsyncOpen(
+    const nsresult& aStatusCode) {
+  if (aStatusCode == NS_ERROR_RECURSIVE_DOCUMENT_LOAD) {
+    // This exists so that we are able to fire an error event
+    // for when there are too many recursive iframe or object loads.
+    // This is an incomplete solution, because right now we don't have a unified
+    // way of firing error events due to errors in document channel.
+    // This should be fixed in bug 1629201.
+    MOZ_DIAGNOSTIC_ASSERT(mLoadingContext);
+    if (RefPtr<Element> embedder = mLoadingContext->GetEmbedderElement()) {
+      if (RefPtr<nsFrameLoaderOwner> flo = do_QueryObject(embedder)) {
+        if (RefPtr<nsFrameLoader> fl = flo->GetFrameLoader()) {
+          fl->FireErrorEvent();
+        }
+      }
+    }
+  }
+  ShutdownListeners(aStatusCode);
+  return IPC_OK();
+}
+
+IPCResult DocumentChannelChild::RecvDisconnectChildListeners(
+    const nsresult& aStatus, const nsresult& aLoadGroupStatus,
+    bool aContinueNavigating) {
+  // If this disconnect is not due to a process switch, perform the disconnect
+  // immediately.
+  if (!aContinueNavigating) {
+    DisconnectChildListeners(aStatus, aLoadGroupStatus);
+    return IPC_OK();
+  }
+
+  // Otherwise, the disconnect will occur later using some other mechanism,
+  // depending on what's happening to the loading DocShell. If this is a
+  // toplevel navigation, and this BrowsingContext enters the BFCache, we will
+  // cancel this channel when the PageHide event is firing, whereas if it does
+  // not enter BFCache (e.g. due to being an object, subframe or non-bfcached
+  // toplevel navigation), we will cancel this channel when the DocShell is
+  // destroyed.
+  nsDocShell* shell = GetDocShell();
+  if (mLoadInfo->GetExternalContentPolicyType() ==
+          ExtContentPolicy::TYPE_DOCUMENT &&
+      shell) {
+    MOZ_ASSERT(shell->GetBrowsingContext()->IsTop());
+    if (mozilla::SessionHistoryInParent() &&
+        shell->GetBrowsingContext()->IsInBFCache()) {
+      DisconnectChildListeners(aStatus, aLoadGroupStatus);
+    } else {
+      // Tell the DocShell which channel to cancel if it enters the BFCache.
+      shell->SetChannelToDisconnectOnPageHide(mChannelId);
+    }
+  }
+
+  return IPC_OK();
+}
+
+IPCResult DocumentChannelChild::RecvRedirectToRealChannel(
+    RedirectToRealChannelArgs&& aArgs,
+    nsTArray<Endpoint<extensions::PStreamFilterParent>>&& aEndpoints,
+    RedirectToRealChannelResolver&& aResolve) {
+  LOG(("DocumentChannelChild RecvRedirectToRealChannel [this=%p, uri=%s]", this,
+       aArgs.uri()->GetSpecOrDefault().get()));
+
+  // The document that created the cspToInherit.
+  // This is used when deserializing LoadInfo from the parent
+  // process, since we can't serialize Documents directly.
+  // TODO: For a fission OOP iframe this will be unavailable,
+  // as will the loadingContext computed in LoadInfoArgsToLoadInfo.
+  // Figure out if we need these for cross-origin subdocs.
+  RefPtr<dom::Document> cspToInheritLoadingDocument;
+  nsCOMPtr<nsIContentSecurityPolicy> policy = mLoadState->Csp();
+  if (policy) {
+    nsWeakPtr ctx =
+        static_cast<nsCSPContext*>(policy.get())->GetLoadingContext();
+    cspToInheritLoadingDocument = do_QueryReferent(ctx);
+  }
+  nsCOMPtr<nsILoadInfo> loadInfo;
+  MOZ_ALWAYS_SUCCEEDS(LoadInfoArgsToLoadInfo(aArgs.loadInfo(), NOT_REMOTE_TYPE,
+                                             cspToInheritLoadingDocument,
+                                             getter_AddRefs(loadInfo)));
+
+  mRedirectResolver = std::move(aResolve);
+
+  nsCOMPtr<nsIChannel> newChannel;
+  MOZ_ASSERT((aArgs.loadStateInternalLoadFlags() &
+              nsDocShell::InternalLoad::INTERNAL_LOAD_FLAGS_IS_SRCDOC) ||
+             aArgs.srcdocData().IsVoid());
+  nsresult rv = nsDocShell::CreateRealChannelForDocument(
+      getter_AddRefs(newChannel), aArgs.uri(), loadInfo, nullptr,
+      aArgs.newLoadFlags(), aArgs.srcdocData(), aArgs.baseUri());
+  if (newChannel) {
+    newChannel->SetLoadGroup(mLoadGroup);
+  }
+
+  if (RefPtr<HttpBaseChannel> httpChannel = do_QueryObject(newChannel)) {
+    httpChannel->SetEarlyHints(std::move(aArgs.earlyHints()));
+    httpChannel->SetEarlyHintLinkType(aArgs.earlyHintLinkType());
+  }
+
+  // This is used to report any errors back to the parent by calling
+  // CrossProcessRedirectFinished.
+  auto scopeExit = MakeScopeExit([&]() {
+    mRedirectResolver(rv);
+    mRedirectResolver = nullptr;
+  });
+
+  if (NS_FAILED(rv)) {
+    return IPC_OK();
+  }
+
+  if (nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(newChannel)) {
+    rv = httpChannel->SetChannelId(aArgs.channelId());
+  }
+  if (NS_FAILED(rv)) {
+    return IPC_OK();
+  }
+
+  rv = newChannel->SetOriginalURI(aArgs.originalURI());
+  if (NS_FAILED(rv)) {
+    return IPC_OK();
+  }
+
+  if (nsCOMPtr<nsIHttpChannelInternal> httpChannelInternal =
+          do_QueryInterface(newChannel)) {
+    rv = httpChannelInternal->SetRedirectMode(aArgs.redirectMode());
+  }
+  if (NS_FAILED(rv)) {
+    return IPC_OK();
+  }
+
+  newChannel->SetNotificationCallbacks(mCallbacks);
+
+  if (aArgs.init()) {
+    HttpBaseChannel::ReplacementChannelConfig config(*aArgs.init());
+    HttpBaseChannel::ConfigureReplacementChannel(
+        newChannel, config,
+        HttpBaseChannel::ReplacementReason::DocumentChannel);
+  }
+
+  if (aArgs.contentDisposition()) {
+    newChannel->SetContentDisposition(*aArgs.contentDisposition());
+  }
+
+  if (aArgs.contentDispositionFilename()) {
+    newChannel->SetContentDispositionFilename(
+        *aArgs.contentDispositionFilename());
+  }
+
+  nsDocShell* docShell = GetDocShell();
+  if (docShell && aArgs.loadingSessionHistoryInfo().isSome()) {
+    docShell->SetLoadingSessionHistoryInfo(
+        aArgs.loadingSessionHistoryInfo().ref());
+  }
+
+  // transfer any properties. This appears to be entirely a content-side
+  // interface and isn't copied across to the parent. Copying the values
+  // for this from this into the new actor will work, since the parent
+  // won't have the right details anyway.
+  // TODO: What about the process switch equivalent
+  // (ContentChild::RecvCrossProcessRedirect)? In that case there is no local
+  // existing actor in the destination process... We really need all information
+  // to go up to the parent, and then come down to the new child actor.
+  if (nsCOMPtr<nsIWritablePropertyBag> bag = do_QueryInterface(newChannel)) {
+    nsHashPropertyBag::CopyFrom(bag, aArgs.properties());
+  }
+
+  // connect parent.
+  nsCOMPtr<nsIChildChannel> childChannel = do_QueryInterface(newChannel);
+  if (childChannel) {
+    rv = childChannel->ConnectParent(
+        aArgs.registrarId());  // creates parent channel
+    if (NS_FAILED(rv)) {
+      return IPC_OK();
+    }
+  }
+  mRedirectChannel = newChannel;
+  mStreamFilterEndpoints = std::move(aEndpoints);
+
+  rv = gHttpHandler->AsyncOnChannelRedirect(this, newChannel,
+                                            aArgs.redirectFlags(),
+                                            GetMainThreadSerialEventTarget());
+
+  if (NS_SUCCEEDED(rv)) {
+    scopeExit.release();
+  }
+
+  // scopeExit will call CrossProcessRedirectFinished(rv) here
+  return IPC_OK();
+}
+
+IPCResult DocumentChannelChild::RecvUpgradeObjectLoad(
+    UpgradeObjectLoadResolver&& aResolve) {
+  // We're doing a load for an <object> or <embed> element if we got here.
+  MOZ_ASSERT(mLoadFlags & nsIRequest::LOAD_HTML_OBJECT_DATA,
+             "Should have LOAD_HTML_OBJECT_DATA set");
+  MOZ_ASSERT(!(mLoadFlags & nsIChannel::LOAD_DOCUMENT_URI),
+             "Shouldn't be a LOAD_DOCUMENT_URI load yet");
+  MOZ_ASSERT(mLoadInfo->GetExternalContentPolicyType() ==
+                 ExtContentPolicy::TYPE_OBJECT,
+             "Should have the TYPE_OBJECT content policy type");
+
+  // If our load has already failed, or been cancelled, abort this attempt to
+  // upgade the load.
+  if (NS_FAILED(mStatus)) {
+    aResolve(nullptr);
+    return IPC_OK();
+  }
+
+  nsCOMPtr<nsIObjectLoadingContent> loadingContent;
+  NS_QueryNotificationCallbacks(this, loadingContent);
+  if (!loadingContent) {
+    return IPC_FAIL(this, "Channel is not for ObjectLoadingContent!");
+  }
+
+  // We're upgrading to a document channel now. Add the LOAD_DOCUMENT_URI flag
+  // after-the-fact.
+  mLoadFlags |= nsIChannel::LOAD_DOCUMENT_URI;
+
+  RefPtr<BrowsingContext> browsingContext;
+  nsresult rv = loadingContent->UpgradeLoadToDocument(
+      this, getter_AddRefs(browsingContext));
+  if (NS_FAILED(rv) || !browsingContext) {
+    // Oops! Looks like something went wrong, so let's bail out.
+    mLoadFlags &= ~nsIChannel::LOAD_DOCUMENT_URI;
+    aResolve(nullptr);
+    return IPC_OK();
+  }
+
+  aResolve(browsingContext);
+  return IPC_OK();
+}
+
+NS_IMETHODIMP
+DocumentChannelChild::OnRedirectVerifyCallback(nsresult aStatusCode) {
+  LOG(
+      ("DocumentChannelChild OnRedirectVerifyCallback [this=%p, "
+       "aRv=0x%08" PRIx32 " ]",
+       this, static_cast<uint32_t>(aStatusCode)));
+  nsCOMPtr<nsIChannel> redirectChannel = std::move(mRedirectChannel);
+  RedirectToRealChannelResolver redirectResolver = std::move(mRedirectResolver);
+
+  // If we've already shut down, then just notify the parent that
+  // we're done.
+  if (NS_FAILED(mStatus)) {
+    redirectChannel->SetNotificationCallbacks(nullptr);
+    redirectResolver(aStatusCode);
+    return NS_OK;
+  }
+
+  nsresult rv = aStatusCode;
+  if (NS_SUCCEEDED(rv)) {
+    if (nsCOMPtr<nsIChildChannel> childChannel =
+            do_QueryInterface(redirectChannel)) {
+      rv = childChannel->CompleteRedirectSetup(mListener);
+    } else {
+      rv = redirectChannel->AsyncOpen(mListener);
+    }
+  } else {
+    redirectChannel->SetNotificationCallbacks(nullptr);
+  }
+
+  for (auto& endpoint : mStreamFilterEndpoints) {
+    extensions::StreamFilterParent::Attach(redirectChannel,
+                                           std::move(endpoint));
+  }
+
+  redirectResolver(rv);
+
+  if (NS_FAILED(rv)) {
+    ShutdownListeners(rv);
+    return NS_OK;
+  }
+
+  if (mLoadGroup) {
+    mLoadGroup->RemoveRequest(this, nullptr, NS_BINDING_REDIRECTED);
+  }
+  mCallbacks = nullptr;
+  mListener = nullptr;
+
+  // This calls NeckoChild::DeallocPDocumentChannel(), which deletes |this| if
+  // IPDL holds the last reference.  Don't rely on |this| existing after here!
+  if (CanSend()) {
+    Send__delete__(this);
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+DocumentChannelChild::Cancel(nsresult aStatusCode) {
+  return CancelWithReason(aStatusCode, "DocumentChannelChild::Cancel"_ns);
+}
+
+NS_IMETHODIMP DocumentChannelChild::CancelWithReason(
+    nsresult aStatusCode, const nsACString& aReason) {
+  if (mCanceled) {
+    return NS_OK;
+  }
+
+  mCanceled = true;
+  if (CanSend()) {
+    SendCancel(aStatusCode, aReason);
+  }
+
+  ShutdownListeners(aStatusCode);
+
+  return NS_OK;
+}
+
+}  // namespace net
+}  // namespace mozilla
+
+#undef LOG
diff --git a/netwerk/ipc/DocumentChannelChild.h b/netwerk/ipc/DocumentChannelChild.h
new file mode 100644
index 0000000000..ac60f20214
--- /dev/null
+++ b/netwerk/ipc/DocumentChannelChild.h
@@ -0,0 +1,75 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_DocumentChannelChild_h
+#define mozilla_net_DocumentChannelChild_h
+
+#include "mozilla/net/PDocumentChannelChild.h"
+#include "mozilla/net/DocumentChannel.h"
+#include "nsIAsyncVerifyRedirectCallback.h"
+#include "mozilla/dom/nsCSPContext.h"
+
+namespace mozilla {
+namespace net {
+
+/**
+ * DocumentChannelChild is an implementation of DocumentChannel for nsDocShells
+ * in the content process, that uses PDocumentChannel to serialize everything
+ * across IPDL to the parent process.
+ */
+class DocumentChannelChild final : public DocumentChannel,
+                                   public nsIAsyncVerifyRedirectCallback,
+                                   public PDocumentChannelChild {
+ public:
+  DocumentChannelChild(nsDocShellLoadState* aLoadState,
+                       class LoadInfo* aLoadInfo, nsLoadFlags aLoadFlags,
+                       uint32_t aCacheKey, bool aUriModified, bool aIsXFOError);
+
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSIASYNCVERIFYREDIRECTCALLBACK
+
+  NS_IMETHOD AsyncOpen(nsIStreamListener* aListener) override;
+  NS_IMETHOD Cancel(nsresult aStatusCode) override;
+  NS_IMETHOD CancelWithReason(nsresult aStatusCode,
+                              const nsACString& aReason) override;
+
+  mozilla::ipc::IPCResult RecvFailedAsyncOpen(const nsresult& aStatusCode);
+
+  mozilla::ipc::IPCResult RecvDisconnectChildListeners(
+      const nsresult& aStatus, const nsresult& aLoadGroupStatus,
+      bool aSwitchedProcess);
+
+  mozilla::ipc::IPCResult RecvDeleteSelf();
+
+  mozilla::ipc::IPCResult RecvRedirectToRealChannel(
+      RedirectToRealChannelArgs&& aArgs,
+      nsTArray<Endpoint<extensions::PStreamFilterParent>>&& aEndpoints,
+      RedirectToRealChannelResolver&& aResolve);
+
+  mozilla::ipc::IPCResult RecvUpgradeObjectLoad(
+      UpgradeObjectLoadResolver&& aResolve);
+
+ private:
+  void DeleteIPDL() override {
+    if (CanSend()) {
+      Send__delete__(this);
+    }
+  }
+
+  ~DocumentChannelChild();
+
+  nsCOMPtr<nsIChannel> mRedirectChannel;
+
+  RedirectToRealChannelResolver mRedirectResolver;
+  nsTArray<Endpoint<extensions::PStreamFilterParent>> mStreamFilterEndpoints;
+  dom::BrowsingContext* mLoadingContext;
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_net_DocumentChannelChild_h
diff --git a/netwerk/ipc/DocumentChannelParent.cpp b/netwerk/ipc/DocumentChannelParent.cpp
new file mode 100644
index 0000000000..302c1ed54c
--- /dev/null
+++ b/netwerk/ipc/DocumentChannelParent.cpp
@@ -0,0 +1,160 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "DocumentChannelParent.h"
+
+#include "mozilla/dom/BrowserParent.h"
+#include "mozilla/dom/CanonicalBrowsingContext.h"
+#include "mozilla/dom/ClientInfo.h"
+#include "mozilla/dom/ContentParent.h"
+#include "mozilla/net/NeckoChannelParams.h"
+#include "nsDocShellLoadState.h"
+
+extern mozilla::LazyLogModule gDocumentChannelLog;
+#define LOG(fmt) MOZ_LOG(gDocumentChannelLog, mozilla::LogLevel::Verbose, fmt)
+
+using namespace mozilla::dom;
+
+namespace mozilla {
+namespace net {
+
+DocumentChannelParent::DocumentChannelParent() {
+  LOG(("DocumentChannelParent ctor [this=%p]", this));
+}
+
+DocumentChannelParent::~DocumentChannelParent() {
+  LOG(("DocumentChannelParent dtor [this=%p]", this));
+}
+
+bool DocumentChannelParent::Init(dom::CanonicalBrowsingContext* aContext,
+                                 const DocumentChannelCreationArgs& aArgs) {
+  RefPtr<nsDocShellLoadState> loadState = aArgs.loadState();
+  LOG(("DocumentChannelParent Init [this=%p, uri=%s]", this,
+       loadState->URI()->GetSpecOrDefault().get()));
+  if (aArgs.parentInitiatedNavigationEpoch() <
+      aContext->GetParentInitiatedNavigationEpoch()) {
+    nsresult rv = NS_BINDING_ABORTED;
+    return SendFailedAsyncOpen(rv);
+  }
+
+  ContentParent* contentParent =
+      static_cast<ContentParent*>(Manager()->Manager());
+
+  RefPtr<DocumentLoadListener::OpenPromise> promise;
+  if (loadState->GetChannelInitialized()) {
+    promise = DocumentLoadListener::ClaimParentLoad(
+        getter_AddRefs(mDocumentLoadListener), loadState->GetLoadIdentifier(),
+        Some(aArgs.channelId()));
+  }
+  if (!promise) {
+    bool isDocumentLoad =
+        aArgs.elementCreationArgs().type() ==
+        DocumentChannelElementCreationArgs::TDocumentCreationArgs;
+    mDocumentLoadListener = new DocumentLoadListener(aContext, isDocumentLoad);
+
+    Maybe<ClientInfo> clientInfo;
+    if (aArgs.initialClientInfo().isSome()) {
+      clientInfo.emplace(ClientInfo(aArgs.initialClientInfo().ref()));
+    }
+
+    nsresult rv = NS_ERROR_UNEXPECTED;
+
+    if (isDocumentLoad) {
+      const DocumentCreationArgs& docArgs = aArgs.elementCreationArgs();
+
+      promise = mDocumentLoadListener->OpenDocument(
+          loadState, aArgs.cacheKey(), Some(aArgs.channelId()),
+          aArgs.asyncOpenTime(), aArgs.timing(), std::move(clientInfo),
+          Some(docArgs.uriModified()), Some(docArgs.isXFOError()),
+          contentParent, &rv);
+    } else {
+      const ObjectCreationArgs& objectArgs = aArgs.elementCreationArgs();
+
+      promise = mDocumentLoadListener->OpenObject(
+          loadState, aArgs.cacheKey(), Some(aArgs.channelId()),
+          aArgs.asyncOpenTime(), aArgs.timing(), std::move(clientInfo),
+          objectArgs.embedderInnerWindowId(), objectArgs.loadFlags(),
+          objectArgs.contentPolicyType(), objectArgs.isUrgentStart(),
+          contentParent, this /* ObjectUpgradeHandler */, &rv);
+    }
+
+    if (NS_FAILED(rv)) {
+      MOZ_ASSERT(!promise);
+      return SendFailedAsyncOpen(rv);
+    }
+  }
+
+  RefPtr<DocumentChannelParent> self = this;
+  promise->Then(
+      GetCurrentSerialEventTarget(), __func__,
+      [self](DocumentLoadListener::OpenPromiseSucceededType&& aResolveValue) {
+        // The DLL is waiting for us to resolve the
+        // PDocumentChannel::RedirectToRealChannelPromise given as parameter.
+        auto promise = self->RedirectToRealChannel(
+            std::move(aResolveValue.mStreamFilterEndpoints),
+            aResolveValue.mRedirectFlags, aResolveValue.mLoadFlags,
+            aResolveValue.mEarlyHintLinkType);
+        // We chain the promise the DLL is waiting on to the one returned by
+        // RedirectToRealChannel. As soon as the promise returned is resolved
+        // or rejected, so will the DLL's promise.
+        promise->ChainTo(aResolveValue.mPromise.forget(), __func__);
+        self->mDocumentLoadListener = nullptr;
+      },
+      [self](DocumentLoadListener::OpenPromiseFailedType&& aRejectValue) {
+        if (self->CanSend()) {
+          Unused << self->SendDisconnectChildListeners(
+              aRejectValue.mStatus, aRejectValue.mLoadGroupStatus,
+              aRejectValue.mContinueNavigating);
+        }
+        self->mDocumentLoadListener = nullptr;
+      });
+
+  return true;
+}
+
+auto DocumentChannelParent::UpgradeObjectLoad()
+    -> RefPtr<ObjectUpgradePromise> {
+  return SendUpgradeObjectLoad()->Then(
+      GetCurrentSerialEventTarget(), __func__,
+      [](const UpgradeObjectLoadPromise::ResolveOrRejectValue& aValue) {
+        if (!aValue.IsResolve() || aValue.ResolveValue().IsNullOrDiscarded()) {
+          LOG(("DocumentChannelParent object load upgrade failed"));
+          return ObjectUpgradePromise::CreateAndReject(NS_ERROR_FAILURE,
+                                                       __func__);
+        }
+
+        return ObjectUpgradePromise::CreateAndResolve(
+            aValue.ResolveValue().get_canonical(), __func__);
+      });
+}
+
+RefPtr<PDocumentChannelParent::RedirectToRealChannelPromise>
+DocumentChannelParent::RedirectToRealChannel(
+    nsTArray<ipc::Endpoint<extensions::PStreamFilterParent>>&&
+        aStreamFilterEndpoints,
+    uint32_t aRedirectFlags, uint32_t aLoadFlags, uint32_t aEarlyHintLinkType) {
+  if (!CanSend()) {
+    return PDocumentChannelParent::RedirectToRealChannelPromise::
+        CreateAndReject(ResponseRejectReason::ChannelClosed, __func__);
+  }
+
+  ContentParent* cp = static_cast<ContentParent*>(Manager()->Manager());
+  nsTArray<EarlyHintConnectArgs> earlyHints;
+  mDocumentLoadListener->RegisterEarlyHintLinksAndGetConnectArgs(cp->ChildID(),
+                                                                 earlyHints);
+
+  RedirectToRealChannelArgs args;
+  mDocumentLoadListener->SerializeRedirectData(
+      args, false, aRedirectFlags, aLoadFlags, cp, std::move(earlyHints),
+      aEarlyHintLinkType);
+  return SendRedirectToRealChannel(args, std::move(aStreamFilterEndpoints));
+}
+
+}  // namespace net
+}  // namespace mozilla
+
+#undef LOG
diff --git a/netwerk/ipc/DocumentChannelParent.h b/netwerk/ipc/DocumentChannelParent.h
new file mode 100644
index 0000000000..7537c95295
--- /dev/null
+++ b/netwerk/ipc/DocumentChannelParent.h
@@ -0,0 +1,68 @@
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_DocumentChannelParent_h
+#define mozilla_net_DocumentChannelParent_h
+
+#include "mozilla/net/DocumentLoadListener.h"
+#include "mozilla/net/PDocumentChannelParent.h"
+
+namespace mozilla {
+namespace dom {
+class CanonicalBrowsingContext;
+}
+namespace net {
+
+class EarlyHintConnectArgs;
+
+/**
+ * An actor that forwards all changes across to DocumentChannelChild, the
+ * nsIChannel implementation owned by a content process docshell.
+ */
+class DocumentChannelParent final
+    : public PDocumentChannelParent,
+      public DocumentLoadListener::ObjectUpgradeHandler {
+ public:
+  NS_INLINE_DECL_REFCOUNTING(DocumentChannelParent, override);
+
+  explicit DocumentChannelParent();
+
+  bool Init(dom::CanonicalBrowsingContext* aContext,
+            const DocumentChannelCreationArgs& aArgs);
+
+  // PDocumentChannelParent
+  ipc::IPCResult RecvCancel(const nsresult& aStatus, const nsCString& aReason) {
+    if (mDocumentLoadListener) {
+      mDocumentLoadListener->Cancel(aStatus, aReason);
+    }
+    return IPC_OK();
+  }
+  void ActorDestroy(ActorDestroyReason aWhy) override {
+    if (mDocumentLoadListener) {
+      mDocumentLoadListener->Cancel(NS_BINDING_ABORTED,
+                                    "DocumentChannelParent::ActorDestroy"_ns);
+    }
+  }
+
+ private:
+  RefPtr<ObjectUpgradePromise> UpgradeObjectLoad() override;
+
+  RefPtr<PDocumentChannelParent::RedirectToRealChannelPromise>
+  RedirectToRealChannel(
+      nsTArray<ipc::Endpoint<extensions::PStreamFilterParent>>&&
+          aStreamFilterEndpoints,
+      uint32_t aRedirectFlags, uint32_t aLoadFlags,
+      uint32_t aEarlyHintLinkType);
+
+  virtual ~DocumentChannelParent();
+
+  RefPtr<DocumentLoadListener> mDocumentLoadListener;
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_net_DocumentChannelParent_h
diff --git a/netwerk/ipc/DocumentLoadListener.cpp b/netwerk/ipc/DocumentLoadListener.cpp
new file mode 100644
index 0000000000..715e00c056
--- /dev/null
+++ b/netwerk/ipc/DocumentLoadListener.cpp
@@ -0,0 +1,2965 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "DocumentLoadListener.h"
+
+#include "NeckoCommon.h"
+#include "mozilla/AntiTrackingUtils.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/LoadInfo.h"
+#include "mozilla/MozPromiseInlines.h"  // For MozPromise::FromDomPromise
+#include "mozilla/NullPrincipal.h"
+#include "mozilla/ResultVariant.h"
+#include "mozilla/ScopeExit.h"
+#include "mozilla/StaticPrefs_extensions.h"
+#include "mozilla/StaticPrefs_fission.h"
+#include "mozilla/StaticPrefs_security.h"
+#include "mozilla/dom/BrowserParent.h"
+#include "mozilla/dom/BrowsingContextGroup.h"
+#include "mozilla/dom/CanonicalBrowsingContext.h"
+#include "mozilla/dom/ChildProcessChannelListener.h"
+#include "mozilla/dom/ClientChannelHelper.h"
+#include "mozilla/dom/ContentParent.h"
+#include "mozilla/dom/ContentProcessManager.h"
+#include "mozilla/dom/ProcessIsolation.h"
+#include "mozilla/dom/SessionHistoryEntry.h"
+#include "mozilla/dom/WindowGlobalParent.h"
+#include "mozilla/dom/ipc/IdType.h"
+#include "mozilla/net/CookieJarSettings.h"
+#include "mozilla/net/HttpChannelParent.h"
+#include "mozilla/net/RedirectChannelRegistrar.h"
+#include "nsContentSecurityUtils.h"
+#include "nsContentSecurityManager.h"
+#include "nsDocShell.h"
+#include "nsDocShellLoadState.h"
+#include "nsDocShellLoadTypes.h"
+#include "nsDOMNavigationTiming.h"
+#include "nsDSURIContentListener.h"
+#include "nsObjectLoadingContent.h"
+#include "nsOpenWindowInfo.h"
+#include "nsExternalHelperAppService.h"
+#include "nsHttpChannel.h"
+#include "nsIBrowser.h"
+#include "nsIHttpChannelInternal.h"
+#include "nsIStreamConverterService.h"
+#include "nsIViewSourceChannel.h"
+#include "nsImportModule.h"
+#include "nsIXULRuntime.h"
+#include "nsMimeTypes.h"
+#include "nsQueryObject.h"
+#include "nsRedirectHistoryEntry.h"
+#include "nsSandboxFlags.h"
+#include "nsSHistory.h"
+#include "nsStringStream.h"
+#include "nsURILoader.h"
+#include "nsWebNavigationInfo.h"
+#include "mozilla/dom/BrowserParent.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/nsHTTPSOnlyUtils.h"
+#include "mozilla/dom/ReferrerInfo.h"
+#include "mozilla/dom/RemoteWebProgressRequest.h"
+#include "mozilla/net/UrlClassifierFeatureFactory.h"
+#include "mozilla/ExtensionPolicyService.h"
+
+#ifdef ANDROID
+#  include "mozilla/widget/nsWindow.h"
+#endif /* ANDROID */
+
+mozilla::LazyLogModule gDocumentChannelLog("DocumentChannel");
+#define LOG(fmt) MOZ_LOG(gDocumentChannelLog, mozilla::LogLevel::Verbose, fmt)
+
+extern mozilla::LazyLogModule gSHIPBFCacheLog;
+
+// Bug 136580: Limit to the number of nested content frames that can have the
+//             same URL. This is to stop content that is recursively loading
+//             itself.  Note that "#foo" on the end of URL doesn't affect
+//             whether it's considered identical, but "?foo" or ";foo" are
+//             considered and compared.
+// Limit this to 2, like chromium does.
+static constexpr int kMaxSameURLContentFrames = 2;
+
+using namespace mozilla::dom;
+
+namespace mozilla {
+namespace net {
+
+static ContentParentId GetContentProcessId(ContentParent* aContentParent) {
+  return aContentParent ? aContentParent->ChildID() : ContentParentId{0};
+}
+
+static void SetNeedToAddURIVisit(nsIChannel* aChannel,
+                                 bool aNeedToAddURIVisit) {
+  nsCOMPtr<nsIWritablePropertyBag2> props(do_QueryInterface(aChannel));
+  if (!props) {
+    return;
+  }
+
+  props->SetPropertyAsBool(u"docshell.needToAddURIVisit"_ns,
+                           aNeedToAddURIVisit);
+}
+
+static auto SecurityFlagsForLoadInfo(nsDocShellLoadState* aLoadState)
+    -> nsSecurityFlags {
+  // TODO: Block copied from nsDocShell::DoURILoad, refactor out somewhere
+  nsSecurityFlags securityFlags =
+      nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_SEC_CONTEXT_IS_NULL;
+
+  if (aLoadState->LoadType() == LOAD_ERROR_PAGE) {
+    securityFlags |= nsILoadInfo::SEC_LOAD_ERROR_PAGE;
+  }
+
+  if (aLoadState->PrincipalToInherit()) {
+    bool isSrcdoc = aLoadState->HasInternalLoadFlags(
+        nsDocShell::INTERNAL_LOAD_FLAGS_IS_SRCDOC);
+    bool inheritAttrs = nsContentUtils::ChannelShouldInheritPrincipal(
+        aLoadState->PrincipalToInherit(), aLoadState->URI(),
+        true,  // aInheritForAboutBlank
+        isSrcdoc);
+
+    bool isData = SchemeIsData(aLoadState->URI());
+    if (inheritAttrs && !isData) {
+      securityFlags |= nsILoadInfo::SEC_FORCE_INHERIT_PRINCIPAL;
+    }
+  }
+
+  return securityFlags;
+}
+
+// Construct a LoadInfo object to use when creating the internal channel for a
+// Document/SubDocument load.
+static auto CreateDocumentLoadInfo(CanonicalBrowsingContext* aBrowsingContext,
+                                   nsDocShellLoadState* aLoadState)
+    -> already_AddRefed<LoadInfo> {
+  uint32_t sandboxFlags = aBrowsingContext->GetSandboxFlags();
+  RefPtr<LoadInfo> loadInfo;
+
+  auto securityFlags = SecurityFlagsForLoadInfo(aLoadState);
+
+  if (aBrowsingContext->GetParent()) {
+    loadInfo = LoadInfo::CreateForFrame(
+        aBrowsingContext, aLoadState->TriggeringPrincipal(),
+        aLoadState->GetEffectiveTriggeringRemoteType(), securityFlags,
+        sandboxFlags);
+  } else {
+    OriginAttributes attrs;
+    aBrowsingContext->GetOriginAttributes(attrs);
+    loadInfo = LoadInfo::CreateForDocument(
+        aBrowsingContext, aLoadState->URI(), aLoadState->TriggeringPrincipal(),
+        aLoadState->GetEffectiveTriggeringRemoteType(), attrs, securityFlags,
+        sandboxFlags);
+  }
+
+  if (aLoadState->IsExemptFromHTTPSOnlyMode()) {
+    uint32_t httpsOnlyStatus = loadInfo->GetHttpsOnlyStatus();
+    httpsOnlyStatus |= nsILoadInfo::HTTPS_ONLY_EXEMPT;
+    loadInfo->SetHttpsOnlyStatus(httpsOnlyStatus);
+  }
+
+  loadInfo->SetTriggeringSandboxFlags(aLoadState->TriggeringSandboxFlags());
+  loadInfo->SetHasValidUserGestureActivation(
+      aLoadState->HasValidUserGestureActivation());
+  loadInfo->SetIsMetaRefresh(aLoadState->IsMetaRefresh());
+
+  return loadInfo.forget();
+}
+
+// Construct a LoadInfo object to use when creating the internal channel for an
+// Object/Embed load.
+static auto CreateObjectLoadInfo(nsDocShellLoadState* aLoadState,
+                                 uint64_t aInnerWindowId,
+                                 nsContentPolicyType aContentPolicyType,
+                                 uint32_t aSandboxFlags)
+    -> already_AddRefed<LoadInfo> {
+  RefPtr<WindowGlobalParent> wgp =
+      WindowGlobalParent::GetByInnerWindowId(aInnerWindowId);
+  MOZ_RELEASE_ASSERT(wgp);
+
+  auto securityFlags = SecurityFlagsForLoadInfo(aLoadState);
+
+  RefPtr<LoadInfo> loadInfo = LoadInfo::CreateForNonDocument(
+      wgp, wgp->DocumentPrincipal(), aContentPolicyType, securityFlags,
+      aSandboxFlags);
+
+  loadInfo->SetHasValidUserGestureActivation(
+      aLoadState->HasValidUserGestureActivation());
+  loadInfo->SetTriggeringSandboxFlags(aLoadState->TriggeringSandboxFlags());
+  loadInfo->SetIsMetaRefresh(aLoadState->IsMetaRefresh());
+
+  return loadInfo.forget();
+}
+
+/**
+ * An extension to nsDocumentOpenInfo that we run in the parent process, so
+ * that we can make the decision to retarget to content handlers or the external
+ * helper app, before we make process switching decisions.
+ *
+ * This modifies the behaviour of nsDocumentOpenInfo so that it can do
+ * retargeting, but doesn't do stream conversion (but confirms that we will be
+ * able to do so later).
+ *
+ * We still run nsDocumentOpenInfo in the content process, but disable
+ * retargeting, so that it can only apply stream conversion, and then send data
+ * to the docshell.
+ */
+class ParentProcessDocumentOpenInfo final : public nsDocumentOpenInfo,
+                                            public nsIMultiPartChannelListener {
+ public:
+  ParentProcessDocumentOpenInfo(ParentChannelListener* aListener,
+                                uint32_t aFlags,
+                                mozilla::dom::BrowsingContext* aBrowsingContext,
+                                bool aIsDocumentLoad)
+      : nsDocumentOpenInfo(aFlags, false),
+        mBrowsingContext(aBrowsingContext),
+        mListener(aListener),
+        mIsDocumentLoad(aIsDocumentLoad) {
+    LOG(("ParentProcessDocumentOpenInfo ctor [this=%p]", this));
+  }
+
+  NS_DECL_ISUPPORTS_INHERITED
+
+  // The default content listener is always a docshell, so this manually
+  // implements the same checks, and if it succeeds, uses the parent
+  // channel listener so that we forward onto DocumentLoadListener.
+  bool TryDefaultContentListener(nsIChannel* aChannel,
+                                 const nsCString& aContentType) {
+    uint32_t canHandle = nsWebNavigationInfo::IsTypeSupported(aContentType);
+    if (canHandle != nsIWebNavigationInfo::UNSUPPORTED) {
+      m_targetStreamListener = mListener;
+      nsLoadFlags loadFlags = 0;
+      aChannel->GetLoadFlags(&loadFlags);
+      aChannel->SetLoadFlags(loadFlags | nsIChannel::LOAD_TARGETED);
+      return true;
+    }
+    return false;
+  }
+
+  bool TryDefaultContentListener(nsIChannel* aChannel) override {
+    return TryDefaultContentListener(aChannel, mContentType);
+  }
+
+  // Generally we only support stream converters that can tell
+  // use exactly what type they'll output. If we find one, then
+  // we just target to our default listener directly (without
+  // conversion), and the content process nsDocumentOpenInfo will
+  // run and do the actual conversion.
+  nsresult TryStreamConversion(nsIChannel* aChannel) override {
+    // The one exception is nsUnknownDecoder, which works in the parent
+    // (and we need to know what the content type is before we can
+    // decide if it will be handled in the parent), so we run that here.
+    if (mContentType.LowerCaseEqualsASCII(UNKNOWN_CONTENT_TYPE) ||
+        mContentType.IsEmpty()) {
+      return nsDocumentOpenInfo::TryStreamConversion(aChannel);
+    }
+
+    nsresult rv;
+    nsCOMPtr<nsIStreamConverterService> streamConvService =
+        do_GetService(NS_STREAMCONVERTERSERVICE_CONTRACTID, &rv);
+    nsAutoCString str;
+    rv = streamConvService->ConvertedType(mContentType, aChannel, str);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    // We only support passing data to the default content listener
+    // (docshell), and we don't supported chaining converters.
+    if (TryDefaultContentListener(aChannel, str)) {
+      mContentType = str;
+      return NS_OK;
+    }
+    // This is the same result as nsStreamConverterService uses when it
+    // can't find a converter
+    return NS_ERROR_FAILURE;
+  }
+
+  nsresult TryExternalHelperApp(nsIExternalHelperAppService* aHelperAppService,
+                                nsIChannel* aChannel) override {
+    RefPtr<nsIStreamListener> listener;
+    nsresult rv = aHelperAppService->CreateListener(
+        mContentType, aChannel, mBrowsingContext, false, nullptr,
+        getter_AddRefs(listener));
+    if (NS_SUCCEEDED(rv)) {
+      m_targetStreamListener = listener;
+    }
+    return rv;
+  }
+
+  nsDocumentOpenInfo* Clone() override {
+    mCloned = true;
+    return new ParentProcessDocumentOpenInfo(mListener, mFlags,
+                                             mBrowsingContext, mIsDocumentLoad);
+  }
+
+  nsresult OnDocumentStartRequest(nsIRequest* request) {
+    LOG(("ParentProcessDocumentOpenInfo OnDocumentStartRequest [this=%p]",
+         this));
+
+    nsresult rv = nsDocumentOpenInfo::OnStartRequest(request);
+
+    // If we didn't find a content handler,
+    // and we don't have a listener, then just forward to our
+    // default listener. This happens when the channel is in
+    // an error state, and we want to just forward that on to be
+    // handled in the content process.
+    if (NS_SUCCEEDED(rv) && !mUsedContentHandler && !m_targetStreamListener) {
+      m_targetStreamListener = mListener;
+      return m_targetStreamListener->OnStartRequest(request);
+    }
+    if (m_targetStreamListener != mListener) {
+      LOG(
+          ("ParentProcessDocumentOpenInfo targeted to non-default listener "
+           "[this=%p]",
+           this));
+      // If this is the only part, then we can immediately tell our listener
+      // that it won't be getting any content and disconnect it. For multipart
+      // channels we have to wait until we've handled all parts before we know.
+      // This does mean that the content process can still Cancel() a multipart
+      // response while the response is being handled externally, but this
+      // matches the single-process behaviour.
+      // If we got cloned, then we don't need to do this, as only the last link
+      // needs to do it.
+      // Multi-part channels are guaranteed to call OnAfterLastPart, which we
+      // forward to the listeners, so it will handle disconnection at that
+      // point.
+      nsCOMPtr<nsIMultiPartChannel> multiPartChannel =
+          do_QueryInterface(request);
+      if (!multiPartChannel && !mCloned) {
+        DisconnectChildListeners(NS_FAILED(rv) ? rv : NS_BINDING_RETARGETED,
+                                 rv);
+      }
+    }
+    return rv;
+  }
+
+  nsresult OnObjectStartRequest(nsIRequest* request) {
+    LOG(("ParentProcessDocumentOpenInfo OnObjectStartRequest [this=%p]", this));
+    // Just redirect to the nsObjectLoadingContent in the content process.
+    m_targetStreamListener = mListener;
+    return m_targetStreamListener->OnStartRequest(request);
+  }
+
+  NS_IMETHOD OnStartRequest(nsIRequest* request) override {
+    LOG(("ParentProcessDocumentOpenInfo OnStartRequest [this=%p]", this));
+
+    if (mIsDocumentLoad) {
+      return OnDocumentStartRequest(request);
+    }
+
+    return OnObjectStartRequest(request);
+  }
+
+  NS_IMETHOD OnAfterLastPart(nsresult aStatus) override {
+    mListener->OnAfterLastPart(aStatus);
+    return NS_OK;
+  }
+
+ private:
+  virtual ~ParentProcessDocumentOpenInfo() {
+    LOG(("ParentProcessDocumentOpenInfo dtor [this=%p]", this));
+  }
+
+  void DisconnectChildListeners(nsresult aStatus, nsresult aLoadGroupStatus) {
+    // Tell the DocumentLoadListener to notify the content process that it's
+    // been entirely retargeted, and to stop waiting.
+    // Clear mListener's pointer to the DocumentLoadListener to break the
+    // reference cycle.
+    RefPtr<DocumentLoadListener> doc = do_GetInterface(ToSupports(mListener));
+    MOZ_ASSERT(doc);
+    doc->DisconnectListeners(aStatus, aLoadGroupStatus);
+    mListener->SetListenerAfterRedirect(nullptr);
+  }
+
+  RefPtr<mozilla::dom::BrowsingContext> mBrowsingContext;
+  RefPtr<ParentChannelListener> mListener;
+  const bool mIsDocumentLoad;
+
+  /**
+   * Set to true if we got cloned to create a chained listener.
+   */
+  bool mCloned = false;
+};
+
+NS_IMPL_ADDREF_INHERITED(ParentProcessDocumentOpenInfo, nsDocumentOpenInfo)
+NS_IMPL_RELEASE_INHERITED(ParentProcessDocumentOpenInfo, nsDocumentOpenInfo)
+
+NS_INTERFACE_MAP_BEGIN(ParentProcessDocumentOpenInfo)
+  NS_INTERFACE_MAP_ENTRY(nsIMultiPartChannelListener)
+NS_INTERFACE_MAP_END_INHERITING(nsDocumentOpenInfo)
+
+NS_IMPL_ADDREF(DocumentLoadListener)
+NS_IMPL_RELEASE(DocumentLoadListener)
+
+NS_INTERFACE_MAP_BEGIN(DocumentLoadListener)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIInterfaceRequestor)
+  NS_INTERFACE_MAP_ENTRY(nsIInterfaceRequestor)
+  NS_INTERFACE_MAP_ENTRY(nsIRequestObserver)
+  NS_INTERFACE_MAP_ENTRY(nsIStreamListener)
+  NS_INTERFACE_MAP_ENTRY(nsIParentChannel)
+  NS_INTERFACE_MAP_ENTRY(nsIAsyncVerifyRedirectReadyCallback)
+  NS_INTERFACE_MAP_ENTRY(nsIChannelEventSink)
+  NS_INTERFACE_MAP_ENTRY(nsIMultiPartChannelListener)
+  NS_INTERFACE_MAP_ENTRY(nsIProgressEventSink)
+  NS_INTERFACE_MAP_ENTRY(nsIEarlyHintObserver)
+  NS_INTERFACE_MAP_ENTRY_CONCRETE(DocumentLoadListener)
+NS_INTERFACE_MAP_END
+
+DocumentLoadListener::DocumentLoadListener(
+    CanonicalBrowsingContext* aLoadingBrowsingContext, bool aIsDocumentLoad)
+    : mIsDocumentLoad(aIsDocumentLoad) {
+  LOG(("DocumentLoadListener ctor [this=%p]", this));
+  mParentChannelListener =
+      new ParentChannelListener(this, aLoadingBrowsingContext);
+}
+
+DocumentLoadListener::~DocumentLoadListener() {
+  LOG(("DocumentLoadListener dtor [this=%p]", this));
+}
+
+void DocumentLoadListener::AddURIVisit(nsIChannel* aChannel,
+                                       uint32_t aLoadFlags) {
+  if (mLoadStateLoadType == LOAD_ERROR_PAGE ||
+      mLoadStateLoadType == LOAD_BYPASS_HISTORY) {
+    return;
+  }
+
+  nsCOMPtr<nsIURI> uri;
+  NS_GetFinalChannelURI(aChannel, getter_AddRefs(uri));
+
+  nsCOMPtr<nsIURI> previousURI;
+  uint32_t previousFlags = 0;
+  if (mLoadStateLoadType & nsIDocShell::LOAD_CMD_RELOAD) {
+    previousURI = uri;
+  } else {
+    nsDocShell::ExtractLastVisit(aChannel, getter_AddRefs(previousURI),
+                                 &previousFlags);
+  }
+
+  // Get the HTTP response code, if available.
+  uint32_t responseStatus = 0;
+  nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(aChannel);
+  if (httpChannel) {
+    Unused << httpChannel->GetResponseStatus(&responseStatus);
+  }
+
+  RefPtr<CanonicalBrowsingContext> browsingContext =
+      GetDocumentBrowsingContext();
+  nsCOMPtr<nsIWidget> widget =
+      browsingContext->GetParentProcessWidgetContaining();
+
+  nsDocShell::InternalAddURIVisit(uri, previousURI, previousFlags,
+                                  responseStatus, browsingContext, widget,
+                                  mLoadStateLoadType);
+}
+
+CanonicalBrowsingContext* DocumentLoadListener::GetLoadingBrowsingContext()
+    const {
+  return mParentChannelListener ? mParentChannelListener->GetBrowsingContext()
+                                : nullptr;
+}
+
+CanonicalBrowsingContext* DocumentLoadListener::GetDocumentBrowsingContext()
+    const {
+  return mIsDocumentLoad ? GetLoadingBrowsingContext() : nullptr;
+}
+
+CanonicalBrowsingContext* DocumentLoadListener::GetTopBrowsingContext() const {
+  auto* loadingContext = GetLoadingBrowsingContext();
+  return loadingContext ? loadingContext->Top() : nullptr;
+}
+
+WindowGlobalParent* DocumentLoadListener::GetParentWindowContext() const {
+  return mParentWindowContext;
+}
+
+bool CheckRecursiveLoad(CanonicalBrowsingContext* aLoadingContext,
+                        nsDocShellLoadState* aLoadState, bool aIsDocumentLoad) {
+  // Bug 136580: Check for recursive frame loading excluding about:srcdoc URIs.
+  // srcdoc URIs require their contents to be specified inline, so it isn't
+  // possible for undesirable recursion to occur without the aid of a
+  // non-srcdoc URI,  which this method will block normally.
+  // Besides, URI is not enough to guarantee uniqueness of srcdoc documents.
+  nsAutoCString buffer;
+  if (aLoadState->URI()->SchemeIs("about")) {
+    nsresult rv = aLoadState->URI()->GetPathQueryRef(buffer);
+    if (NS_SUCCEEDED(rv) && buffer.EqualsLiteral("srcdoc")) {
+      // Duplicates allowed up to depth limits
+      return true;
+    }
+  }
+
+  RefPtr<WindowGlobalParent> parent;
+  if (!aIsDocumentLoad) {  // object load
+    parent = aLoadingContext->GetCurrentWindowGlobal();
+  } else {
+    parent = aLoadingContext->GetParentWindowContext();
+  }
+
+  int matchCount = 0;
+  CanonicalBrowsingContext* ancestorBC;
+  for (WindowGlobalParent* ancestorWGP = parent; ancestorWGP;
+       ancestorWGP = ancestorBC->GetParentWindowContext()) {
+    ancestorBC = ancestorWGP->BrowsingContext();
+    MOZ_ASSERT(ancestorBC);
+    if (nsCOMPtr<nsIURI> parentURI = ancestorWGP->GetDocumentURI()) {
+      bool equal;
+      nsresult rv = aLoadState->URI()->EqualsExceptRef(parentURI, &equal);
+      NS_ENSURE_SUCCESS(rv, false);
+
+      if (equal) {
+        matchCount++;
+        if (matchCount >= kMaxSameURLContentFrames) {
+          NS_WARNING(
+              "Too many nested content frames/objects have the same url "
+              "(recursion?) "
+              "so giving up");
+          return false;
+        }
+      }
+    }
+  }
+  return true;
+}
+
+// Check that the load state, potentially received from a child process, appears
+// to be performing a load of the specified LoadingSessionHistoryInfo.
+// Returns a Result<…> containing the SessionHistoryEntry found for the
+// LoadingSessionHistoryInfo as success value if the validation succeeded, or a
+// static (telemetry-safe) string naming what did not match as a failure value
+// if the validation failed.
+static Result<SessionHistoryEntry*, const char*> ValidateHistoryLoad(
+    CanonicalBrowsingContext* aLoadingContext,
+    nsDocShellLoadState* aLoadState) {
+  MOZ_ASSERT(SessionHistoryInParent());
+  MOZ_ASSERT(aLoadState->LoadIsFromSessionHistory());
+
+  if (!aLoadState->GetLoadingSessionHistoryInfo()) {
+    return Err("Missing LoadingSessionHistoryInfo");
+  }
+
+  SessionHistoryEntry::LoadingEntry* loading = SessionHistoryEntry::GetByLoadId(
+      aLoadState->GetLoadingSessionHistoryInfo()->mLoadId);
+  if (!loading) {
+    return Err("Missing SessionHistoryEntry");
+  }
+
+  SessionHistoryInfo* snapshot = loading->mInfoSnapshotForValidation.get();
+  // History loads do not inherit principal.
+  if (aLoadState->HasInternalLoadFlags(
+          nsDocShell::INTERNAL_LOAD_FLAGS_INHERIT_PRINCIPAL)) {
+    return Err("LOAD_FLAGS_INHERIT_PRINCIPAL");
+  }
+
+  auto uriEq = [](nsIURI* a, nsIURI* b) -> bool {
+    bool eq = false;
+    return a == b || (a && b && NS_SUCCEEDED(a->Equals(b, &eq)) && eq);
+  };
+  auto principalEq = [](nsIPrincipal* a, nsIPrincipal* b) -> bool {
+    return a == b || (a && b && a->Equals(b));
+  };
+
+  // XXX: Needing to do all of this validation manually is kinda gross.
+  if (!uriEq(snapshot->GetURI(), aLoadState->URI())) {
+    return Err("URI");
+  }
+  if (!uriEq(snapshot->GetOriginalURI(), aLoadState->OriginalURI())) {
+    return Err("OriginalURI");
+  }
+  if (!aLoadState->ResultPrincipalURIIsSome() ||
+      !uriEq(snapshot->GetResultPrincipalURI(),
+             aLoadState->ResultPrincipalURI())) {
+    return Err("ResultPrincipalURI");
+  }
+  if (!uriEq(snapshot->GetUnstrippedURI(), aLoadState->GetUnstrippedURI())) {
+    return Err("UnstrippedURI");
+  }
+  if (!principalEq(snapshot->GetTriggeringPrincipal(),
+                   aLoadState->TriggeringPrincipal())) {
+    return Err("TriggeringPrincipal");
+  }
+  if (!principalEq(snapshot->GetPrincipalToInherit(),
+                   aLoadState->PrincipalToInherit())) {
+    return Err("PrincipalToInherit");
+  }
+  if (!principalEq(snapshot->GetPartitionedPrincipalToInherit(),
+                   aLoadState->PartitionedPrincipalToInherit())) {
+    return Err("PartitionedPrincipalToInherit");
+  }
+
+  // Everything matches!
+  return loading->mEntry;
+}
+
+auto DocumentLoadListener::Open(nsDocShellLoadState* aLoadState,
+                                LoadInfo* aLoadInfo, nsLoadFlags aLoadFlags,
+                                uint32_t aCacheKey,
+                                const Maybe<uint64_t>& aChannelId,
+                                const TimeStamp& aAsyncOpenTime,
+                                nsDOMNavigationTiming* aTiming,
+                                Maybe<ClientInfo>&& aInfo, bool aUrgentStart,
+                                dom::ContentParent* aContentParent,
+                                nsresult* aRv) -> RefPtr<OpenPromise> {
+  auto* loadingContext = GetLoadingBrowsingContext();
+
+  MOZ_DIAGNOSTIC_ASSERT_IF(loadingContext->GetParent(),
+                           loadingContext->GetParentWindowContext());
+
+  OriginAttributes attrs;
+  loadingContext->GetOriginAttributes(attrs);
+
+  mLoadIdentifier = aLoadState->GetLoadIdentifier();
+  // See description of  mFileName in nsDocShellLoadState.h
+  mIsDownload = !aLoadState->FileName().IsVoid();
+  mIsLoadingJSURI = net::SchemeIsJavascript(aLoadState->URI());
+
+  // Check for infinite recursive object or iframe loads
+  if (aLoadState->OriginalFrameSrc() || !mIsDocumentLoad) {
+    if (!CheckRecursiveLoad(loadingContext, aLoadState, mIsDocumentLoad)) {
+      *aRv = NS_ERROR_RECURSIVE_DOCUMENT_LOAD;
+      mParentChannelListener = nullptr;
+      return nullptr;
+    }
+  }
+
+  auto* documentContext = GetDocumentBrowsingContext();
+
+  // If we are using SHIP and this load is from session history, validate that
+  // the load matches our local copy of the loading history entry.
+  //
+  // NOTE: Keep this check in-sync with the check in
+  // `nsDocShellLoadState::GetEffectiveTriggeringRemoteType()`!
+  RefPtr<SessionHistoryEntry> existingEntry;
+  if (SessionHistoryInParent() && aLoadState->LoadIsFromSessionHistory() &&
+      aLoadState->LoadType() != LOAD_ERROR_PAGE) {
+    Result<SessionHistoryEntry*, const char*> result =
+        ValidateHistoryLoad(loadingContext, aLoadState);
+    if (result.isErr()) {
+      const char* mismatch = result.unwrapErr();
+      LOG(
+          ("DocumentLoadListener::Open with invalid loading history entry "
+           "[this=%p, mismatch=%s]",
+           this, mismatch));
+#ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
+      MOZ_CRASH_UNSAFE_PRINTF(
+          "DocumentLoadListener::Open for invalid history entry due to "
+          "mismatch of '%s'",
+          mismatch);
+#endif
+      *aRv = NS_ERROR_DOM_SECURITY_ERR;
+      mParentChannelListener = nullptr;
+      return nullptr;
+    }
+
+    existingEntry = result.unwrap();
+    if (!existingEntry->IsInSessionHistory() &&
+        !documentContext->HasLoadingHistoryEntry(existingEntry)) {
+      SessionHistoryEntry::RemoveLoadId(
+          aLoadState->GetLoadingSessionHistoryInfo()->mLoadId);
+      LOG(
+          ("DocumentLoadListener::Open with disconnected history entry "
+           "[this=%p]",
+           this));
+
+      *aRv = NS_BINDING_ABORTED;
+      mParentChannelListener = nullptr;
+      mChannel = nullptr;
+      return nullptr;
+    }
+  }
+
+  if (aLoadState->GetRemoteTypeOverride()) {
+    if (!mIsDocumentLoad || !NS_IsAboutBlank(aLoadState->URI()) ||
+        !loadingContext->IsTopContent()) {
+      LOG(
+          ("DocumentLoadListener::Open with invalid remoteTypeOverride "
+           "[this=%p]",
+           this));
+      *aRv = NS_ERROR_DOM_SECURITY_ERR;
+      mParentChannelListener = nullptr;
+      return nullptr;
+    }
+
+    mRemoteTypeOverride = aLoadState->GetRemoteTypeOverride();
+  }
+
+  if (NS_WARN_IF(!loadingContext->IsOwnedByProcess(
+          GetContentProcessId(aContentParent)))) {
+    LOG(
+        ("DocumentLoadListener::Open called from non-current content process "
+         "[this=%p, current=%" PRIu64 ", caller=%" PRIu64 "]",
+         this, loadingContext->OwnerProcessId(),
+         uint64_t(GetContentProcessId(aContentParent))));
+    *aRv = NS_BINDING_ABORTED;
+    mParentChannelListener = nullptr;
+    return nullptr;
+  }
+
+  if (mIsDocumentLoad && loadingContext->IsContent() &&
+      NS_WARN_IF(loadingContext->IsReplaced())) {
+    LOG(
+        ("DocumentLoadListener::Open called from replaced BrowsingContext "
+         "[this=%p, browserid=%" PRIx64 ", bcid=%" PRIx64 "]",
+         this, loadingContext->BrowserId(), loadingContext->Id()));
+    *aRv = NS_BINDING_ABORTED;
+    mParentChannelListener = nullptr;
+    return nullptr;
+  }
+
+  if (!nsDocShell::CreateAndConfigureRealChannelForLoadState(
+          loadingContext, aLoadState, aLoadInfo, mParentChannelListener,
+          nullptr, attrs, aLoadFlags, aCacheKey, *aRv,
+          getter_AddRefs(mChannel))) {
+    LOG(("DocumentLoadListener::Open failed to create channel [this=%p]",
+         this));
+    mParentChannelListener = nullptr;
+    return nullptr;
+  }
+
+  if (documentContext && aLoadState->LoadType() != LOAD_ERROR_PAGE &&
+      mozilla::SessionHistoryInParent()) {
+    // It's hard to know at this point whether session history will be enabled
+    // in the browsing context, so we always create an entry for a load here.
+    mLoadingSessionHistoryInfo =
+        documentContext->CreateLoadingSessionHistoryEntryForLoad(
+            aLoadState, existingEntry, mChannel);
+    MOZ_ASSERT(mLoadingSessionHistoryInfo);
+  }
+
+  nsCOMPtr<nsIURI> uriBeingLoaded;
+  Unused << NS_WARN_IF(
+      NS_FAILED(mChannel->GetURI(getter_AddRefs(uriBeingLoaded))));
+
+  RefPtr<HttpBaseChannel> httpBaseChannel = do_QueryObject(mChannel, aRv);
+  if (uriBeingLoaded && httpBaseChannel) {
+    nsCOMPtr<nsIURI> topWindowURI;
+    if (mIsDocumentLoad && loadingContext->IsTop()) {
+      // If this is for the top level loading, the top window URI should be the
+      // URI which we are loading.
+      topWindowURI = uriBeingLoaded;
+    } else if (RefPtr<WindowGlobalParent> topWindow = AntiTrackingUtils::
+                   GetTopWindowExcludingExtensionAccessibleContentFrames(
+                       loadingContext, uriBeingLoaded)) {
+      nsCOMPtr<nsIPrincipal> topWindowPrincipal =
+          topWindow->DocumentPrincipal();
+      if (topWindowPrincipal && !topWindowPrincipal->GetIsNullPrincipal()) {
+        auto* basePrin = BasePrincipal::Cast(topWindowPrincipal);
+        basePrin->GetURI(getter_AddRefs(topWindowURI));
+      }
+    }
+    httpBaseChannel->SetTopWindowURI(topWindowURI);
+  }
+
+  nsCOMPtr<nsIIdentChannel> identChannel = do_QueryInterface(mChannel);
+  if (identChannel && aChannelId) {
+    Unused << identChannel->SetChannelId(*aChannelId);
+  }
+  mDocumentChannelId = aChannelId;
+
+  RefPtr<nsHttpChannel> httpChannelImpl = do_QueryObject(mChannel);
+  if (httpChannelImpl) {
+    httpChannelImpl->SetWarningReporter(this);
+
+    if (mIsDocumentLoad && loadingContext->IsTop()) {
+      httpChannelImpl->SetEarlyHintObserver(this);
+    }
+  }
+
+  nsCOMPtr<nsITimedChannel> timedChannel = do_QueryInterface(mChannel);
+  if (timedChannel) {
+    timedChannel->SetAsyncOpen(aAsyncOpenTime);
+  }
+
+  if (nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(mChannel)) {
+    Unused << httpChannel->SetRequestContextID(
+        loadingContext->GetRequestContextId());
+
+    nsCOMPtr<nsIClassOfService> cos(do_QueryInterface(httpChannel));
+    if (cos && aUrgentStart) {
+      cos->AddClassFlags(nsIClassOfService::UrgentStart);
+    }
+  }
+
+  // Setup a ClientChannelHelper to watch for redirects, and copy
+  // across any serviceworker related data between channels as needed.
+  AddClientChannelHelperInParent(mChannel, std::move(aInfo));
+
+  if (documentContext && !documentContext->StartDocumentLoad(this)) {
+    LOG(("DocumentLoadListener::Open failed StartDocumentLoad [this=%p]",
+         this));
+    *aRv = NS_BINDING_ABORTED;
+    mParentChannelListener = nullptr;
+    mChannel = nullptr;
+    return nullptr;
+  }
+
+  // Recalculate the openFlags, matching the logic in use in Content process.
+  // NOTE: The only case not handled here to mirror Content process is
+  // redirecting to re-use the channel.
+  MOZ_ASSERT(!aLoadState->GetPendingRedirectedChannel());
+  uint32_t openFlags =
+      nsDocShell::ComputeURILoaderFlags(loadingContext, aLoadState->LoadType());
+
+  RefPtr<ParentProcessDocumentOpenInfo> openInfo =
+      new ParentProcessDocumentOpenInfo(mParentChannelListener, openFlags,
+                                        loadingContext, mIsDocumentLoad);
+  openInfo->Prepare();
+
+#ifdef ANDROID
+  RefPtr<MozPromise<bool, bool, false>> promise;
+  if (documentContext && aLoadState->LoadType() != LOAD_ERROR_PAGE &&
+      !(aLoadState->HasInternalLoadFlags(
+          nsDocShell::INTERNAL_LOAD_FLAGS_BYPASS_LOAD_URI_DELEGATE)) &&
+      !(aLoadState->LoadType() & LOAD_HISTORY)) {
+    nsCOMPtr<nsIWidget> widget =
+        documentContext->GetParentProcessWidgetContaining();
+    RefPtr<nsWindow> window = nsWindow::From(widget);
+
+    if (window) {
+      promise = window->OnLoadRequest(
+          aLoadState->URI(), nsIBrowserDOMWindow::OPEN_CURRENTWINDOW,
+          aLoadState->InternalLoadFlags(), aLoadState->TriggeringPrincipal(),
+          aLoadState->HasValidUserGestureActivation(),
+          documentContext->IsTopContent());
+    }
+  }
+
+  if (promise) {
+    RefPtr<DocumentLoadListener> self = this;
+    promise->Then(
+        GetCurrentSerialEventTarget(), __func__,
+        [=](const MozPromise<bool, bool, false>::ResolveOrRejectValue& aValue) {
+          if (aValue.IsResolve()) {
+            bool handled = aValue.ResolveValue();
+            if (handled) {
+              self->DisconnectListeners(NS_ERROR_ABORT, NS_ERROR_ABORT);
+              mParentChannelListener = nullptr;
+            } else {
+              nsresult rv = mChannel->AsyncOpen(openInfo);
+              if (NS_FAILED(rv)) {
+                self->DisconnectListeners(rv, rv);
+                mParentChannelListener = nullptr;
+              }
+            }
+          }
+        });
+  } else
+#endif /* ANDROID */
+  {
+    *aRv = mChannel->AsyncOpen(openInfo);
+    if (NS_FAILED(*aRv)) {
+      LOG(("DocumentLoadListener::Open failed AsyncOpen [this=%p rv=%" PRIx32
+           "]",
+           this, static_cast<uint32_t>(*aRv)));
+      if (documentContext) {
+        documentContext->EndDocumentLoad(false);
+      }
+      mParentChannelListener = nullptr;
+      return nullptr;
+    }
+  }
+
+  // HTTPS-Only Mode fights potential timeouts caused by upgrades. Instantly
+  // after opening the document channel we have to kick off countermeasures.
+  nsHTTPSOnlyUtils::PotentiallyFireHttpRequestToShortenTimout(this);
+
+  nsCOMPtr<nsILoadInfo> loadInfo = mChannel->LoadInfo();
+  loadInfo->SetChannelCreationOriginalURI(aLoadState->URI());
+
+  mContentParent = aContentParent;
+  mLoadStateExternalLoadFlags = aLoadState->LoadFlags();
+  mLoadStateInternalLoadFlags = aLoadState->InternalLoadFlags();
+  mLoadStateLoadType = aLoadState->LoadType();
+  mTiming = aTiming;
+  mSrcdocData = aLoadState->SrcdocData();
+  mBaseURI = aLoadState->BaseURI();
+  mOriginalUriString = aLoadState->GetOriginalURIString();
+  if (documentContext) {
+    mParentWindowContext = documentContext->GetParentWindowContext();
+  } else {
+    mParentWindowContext =
+        WindowGlobalParent::GetByInnerWindowId(aLoadInfo->GetInnerWindowID());
+    MOZ_RELEASE_ASSERT(mParentWindowContext->GetBrowsingContext() ==
+                           GetLoadingBrowsingContext(),
+                       "mismatched parent window context?");
+  }
+
+  // For content-initiated loads, this flag is set in nsDocShell::LoadURI.
+  // For parent-initiated loads, we have to set it here.
+  // Below comment is copied from nsDocShell::LoadURI -
+  // If we have a system triggering principal, we can assume that this load was
+  // triggered by some UI in the browser chrome, such as the URL bar or
+  // bookmark bar. This should count as a user interaction for the current sh
+  // entry, so that the user may navigate back to the current entry, from the
+  // entry that is going to be added as part of this load.
+  if (!mSupportsRedirectToRealChannel && aLoadState->TriggeringPrincipal() &&
+      aLoadState->TriggeringPrincipal()->IsSystemPrincipal()) {
+    WindowContext* topWc = loadingContext->GetTopWindowContext();
+    if (topWc && !topWc->IsDiscarded()) {
+      MOZ_ALWAYS_SUCCEEDS(topWc->SetSHEntryHasUserInteraction(true));
+    }
+  }
+
+  *aRv = NS_OK;
+  mOpenPromise = new OpenPromise::Private(__func__);
+  // We make the promise use direct task dispatch in order to reduce the number
+  // of event loops iterations.
+  mOpenPromise->UseDirectTaskDispatch(__func__);
+  return mOpenPromise;
+}
+
+auto DocumentLoadListener::OpenDocument(
+    nsDocShellLoadState* aLoadState, uint32_t aCacheKey,
+    const Maybe<uint64_t>& aChannelId, const TimeStamp& aAsyncOpenTime,
+    nsDOMNavigationTiming* aTiming, Maybe<dom::ClientInfo>&& aInfo,
+    Maybe<bool> aUriModified, Maybe<bool> aIsXFOError,
+    dom::ContentParent* aContentParent, nsresult* aRv) -> RefPtr<OpenPromise> {
+  LOG(("DocumentLoadListener [%p] OpenDocument [uri=%s]", this,
+       aLoadState->URI()->GetSpecOrDefault().get()));
+
+  MOZ_ASSERT(mIsDocumentLoad);
+
+  RefPtr<CanonicalBrowsingContext> browsingContext =
+      GetDocumentBrowsingContext();
+
+  // If this is a top-level load, then rebuild the LoadInfo from scratch,
+  // since the goal is to be able to initiate loads in the parent, where the
+  // content process won't have provided us with an existing one.
+  RefPtr<LoadInfo> loadInfo =
+      CreateDocumentLoadInfo(browsingContext, aLoadState);
+
+  nsLoadFlags loadFlags = aLoadState->CalculateChannelLoadFlags(
+      browsingContext, std::move(aUriModified), std::move(aIsXFOError));
+
+  return Open(aLoadState, loadInfo, loadFlags, aCacheKey, aChannelId,
+              aAsyncOpenTime, aTiming, std::move(aInfo), false, aContentParent,
+              aRv);
+}
+
+auto DocumentLoadListener::OpenObject(
+    nsDocShellLoadState* aLoadState, uint32_t aCacheKey,
+    const Maybe<uint64_t>& aChannelId, const TimeStamp& aAsyncOpenTime,
+    nsDOMNavigationTiming* aTiming, Maybe<dom::ClientInfo>&& aInfo,
+    uint64_t aInnerWindowId, nsLoadFlags aLoadFlags,
+    nsContentPolicyType aContentPolicyType, bool aUrgentStart,
+    dom::ContentParent* aContentParent,
+    ObjectUpgradeHandler* aObjectUpgradeHandler, nsresult* aRv)
+    -> RefPtr<OpenPromise> {
+  LOG(("DocumentLoadListener [%p] OpenObject [uri=%s]", this,
+       aLoadState->URI()->GetSpecOrDefault().get()));
+
+  MOZ_ASSERT(!mIsDocumentLoad);
+
+  auto sandboxFlags = aLoadState->TriggeringSandboxFlags();
+
+  RefPtr<LoadInfo> loadInfo = CreateObjectLoadInfo(
+      aLoadState, aInnerWindowId, aContentPolicyType, sandboxFlags);
+
+  mObjectUpgradeHandler = aObjectUpgradeHandler;
+
+  return Open(aLoadState, loadInfo, aLoadFlags, aCacheKey, aChannelId,
+              aAsyncOpenTime, aTiming, std::move(aInfo), aUrgentStart,
+              aContentParent, aRv);
+}
+
+auto DocumentLoadListener::OpenInParent(nsDocShellLoadState* aLoadState,
+                                        bool aSupportsRedirectToRealChannel)
+    -> RefPtr<OpenPromise> {
+  MOZ_ASSERT(mIsDocumentLoad);
+
+  // We currently only support passing nullptr for aLoadInfo for
+  // top level browsing contexts.
+  auto* browsingContext = GetDocumentBrowsingContext();
+  if (!browsingContext->IsTopContent() ||
+      !browsingContext->GetContentParent()) {
+    LOG(("DocumentLoadListener::OpenInParent failed because of subdoc"));
+    return nullptr;
+  }
+
+  if (nsCOMPtr<nsIContentSecurityPolicy> csp = aLoadState->Csp()) {
+    // Check CSP navigate-to
+    bool allowsNavigateTo = false;
+    nsresult rv = csp->GetAllowsNavigateTo(aLoadState->URI(),
+                                           aLoadState->IsFormSubmission(),
+                                           false, /* aWasRedirected */
+                                           false, /* aEnforceWhitelist */
+                                           &allowsNavigateTo);
+    if (NS_FAILED(rv) || !allowsNavigateTo) {
+      return nullptr;
+    }
+  }
+
+  // Clone because this mutates the load flags in the load state, which
+  // breaks nsDocShells expectations of being able to do it.
+  RefPtr<nsDocShellLoadState> loadState = new nsDocShellLoadState(*aLoadState);
+  loadState->CalculateLoadURIFlags();
+
+  RefPtr<nsDOMNavigationTiming> timing = new nsDOMNavigationTiming(nullptr);
+  timing->NotifyNavigationStart(
+      browsingContext->IsActive()
+          ? nsDOMNavigationTiming::DocShellState::eActive
+          : nsDOMNavigationTiming::DocShellState::eInactive);
+
+  const mozilla::dom::LoadingSessionHistoryInfo* loadingInfo =
+      loadState->GetLoadingSessionHistoryInfo();
+
+  uint32_t cacheKey = 0;
+  auto loadType = aLoadState->LoadType();
+  if (loadType == LOAD_HISTORY || loadType == LOAD_RELOAD_NORMAL ||
+      loadType == LOAD_RELOAD_CHARSET_CHANGE ||
+      loadType == LOAD_RELOAD_CHARSET_CHANGE_BYPASS_CACHE ||
+      loadType == LOAD_RELOAD_CHARSET_CHANGE_BYPASS_PROXY_AND_CACHE) {
+    if (loadingInfo) {
+      cacheKey = loadingInfo->mInfo.GetCacheKey();
+    }
+  }
+
+  // Loads start in the content process might have exposed a channel id to
+  // observers, so we need to preserve the value in the parent. That can't have
+  // happened here, so Nothing() is fine.
+  Maybe<uint64_t> channelId = Nothing();
+
+  // Initial client info is only relevant for subdocument loads, which we're
+  // not supporting yet.
+  Maybe<dom::ClientInfo> initialClientInfo;
+
+  mSupportsRedirectToRealChannel = aSupportsRedirectToRealChannel;
+
+  // This is a top-level load, so rebuild the LoadInfo from scratch,
+  // since in the parent the
+  // content process won't have provided us with an existing one.
+  RefPtr<LoadInfo> loadInfo =
+      CreateDocumentLoadInfo(browsingContext, aLoadState);
+
+  nsLoadFlags loadFlags = loadState->CalculateChannelLoadFlags(
+      browsingContext,
+      Some(loadingInfo && loadingInfo->mInfo.GetURIWasModified()), Nothing());
+
+  nsresult rv;
+  return Open(loadState, loadInfo, loadFlags, cacheKey, channelId,
+              TimeStamp::Now(), timing, std::move(initialClientInfo), false,
+              browsingContext->GetContentParent(), &rv);
+}
+
+base::ProcessId DocumentLoadListener::OtherPid() const {
+  return mContentParent ? mContentParent->OtherPid() : base::ProcessId{0};
+}
+
+void DocumentLoadListener::FireStateChange(uint32_t aStateFlags,
+                                           nsresult aStatus) {
+  nsCOMPtr<nsIChannel> request = GetChannel();
+
+  RefPtr<BrowsingContextWebProgress> webProgress =
+      GetLoadingBrowsingContext()->GetWebProgress();
+
+  if (webProgress) {
+    NS_DispatchToMainThread(
+        NS_NewRunnableFunction("DocumentLoadListener::FireStateChange", [=]() {
+          webProgress->OnStateChange(webProgress, request, aStateFlags,
+                                     aStatus);
+        }));
+  }
+}
+
+static void SetNavigating(CanonicalBrowsingContext* aBrowsingContext,
+                          bool aNavigating) {
+  nsCOMPtr<nsIBrowser> browser;
+  if (RefPtr<Element> currentElement = aBrowsingContext->GetEmbedderElement()) {
+    browser = currentElement->AsBrowser();
+  }
+
+  if (!browser) {
+    return;
+  }
+
+  NS_DispatchToMainThread(NS_NewRunnableFunction(
+      "DocumentLoadListener::SetNavigating",
+      [browser, aNavigating]() { browser->SetIsNavigating(aNavigating); }));
+}
+
+/* static */ bool DocumentLoadListener::LoadInParent(
+    CanonicalBrowsingContext* aBrowsingContext, nsDocShellLoadState* aLoadState,
+    bool aSetNavigating) {
+  SetNavigating(aBrowsingContext, aSetNavigating);
+
+  RefPtr<DocumentLoadListener> load =
+      new DocumentLoadListener(aBrowsingContext, true);
+  RefPtr<DocumentLoadListener::OpenPromise> promise = load->OpenInParent(
+      aLoadState, /* aSupportsRedirectToRealChannel */ false);
+  if (!promise) {
+    SetNavigating(aBrowsingContext, false);
+    return false;
+  }
+
+  // We passed false for aSupportsRedirectToRealChannel, so we should always
+  // take the process switching path, and reject this promise.
+  promise->Then(
+      GetCurrentSerialEventTarget(), __func__,
+      [load](DocumentLoadListener::OpenPromise::ResolveOrRejectValue&& aValue) {
+        MOZ_ASSERT(aValue.IsReject());
+        DocumentLoadListener::OpenPromiseFailedType& rejectValue =
+            aValue.RejectValue();
+        if (!rejectValue.mContinueNavigating) {
+          // If we're not switching the load to a new process, then it is
+          // finished (and failed), and we should fire a state change to notify
+          // observers. Normally the docshell would fire this, and it would get
+          // filtered out by BrowserParent if needed.
+          load->FireStateChange(nsIWebProgressListener::STATE_STOP |
+                                    nsIWebProgressListener::STATE_IS_WINDOW |
+                                    nsIWebProgressListener::STATE_IS_NETWORK,
+                                rejectValue.mStatus);
+        }
+      });
+
+  load->FireStateChange(nsIWebProgressListener::STATE_START |
+                            nsIWebProgressListener::STATE_IS_DOCUMENT |
+                            nsIWebProgressListener::STATE_IS_REQUEST |
+                            nsIWebProgressListener::STATE_IS_WINDOW |
+                            nsIWebProgressListener::STATE_IS_NETWORK,
+                        NS_OK);
+  SetNavigating(aBrowsingContext, false);
+  return true;
+}
+
+/* static */
+bool DocumentLoadListener::SpeculativeLoadInParent(
+    dom::CanonicalBrowsingContext* aBrowsingContext,
+    nsDocShellLoadState* aLoadState) {
+  LOG(("DocumentLoadListener::OpenFromParent"));
+
+  RefPtr<DocumentLoadListener> listener =
+      new DocumentLoadListener(aBrowsingContext, true);
+
+  auto promise = listener->OpenInParent(aLoadState, true);
+  if (promise) {
+    // Create an entry in the redirect channel registrar to
+    // allocate an identifier for this load.
+    nsCOMPtr<nsIRedirectChannelRegistrar> registrar =
+        RedirectChannelRegistrar::GetOrCreate();
+    uint64_t loadIdentifier = aLoadState->GetLoadIdentifier();
+    DebugOnly<nsresult> rv =
+        registrar->RegisterChannel(nullptr, loadIdentifier);
+    MOZ_ASSERT(NS_SUCCEEDED(rv));
+    // Register listener (as an nsIParentChannel) under our new identifier.
+    rv = registrar->LinkChannels(loadIdentifier, listener, nullptr);
+    MOZ_ASSERT(NS_SUCCEEDED(rv));
+  }
+  return !!promise;
+}
+
+void DocumentLoadListener::CleanupParentLoadAttempt(uint64_t aLoadIdent) {
+  nsCOMPtr<nsIRedirectChannelRegistrar> registrar =
+      RedirectChannelRegistrar::GetOrCreate();
+
+  nsCOMPtr<nsIParentChannel> parentChannel;
+  registrar->GetParentChannel(aLoadIdent, getter_AddRefs(parentChannel));
+  RefPtr<DocumentLoadListener> loadListener = do_QueryObject(parentChannel);
+
+  if (loadListener) {
+    // If the load listener is still registered, then we must have failed
+    // to connect DocumentChannel into it. Better cancel it!
+    loadListener->NotifyDocumentChannelFailed();
+  }
+
+  registrar->DeregisterChannels(aLoadIdent);
+}
+
+auto DocumentLoadListener::ClaimParentLoad(DocumentLoadListener** aListener,
+                                           uint64_t aLoadIdent,
+                                           Maybe<uint64_t> aChannelId)
+    -> RefPtr<OpenPromise> {
+  nsCOMPtr<nsIRedirectChannelRegistrar> registrar =
+      RedirectChannelRegistrar::GetOrCreate();
+
+  nsCOMPtr<nsIParentChannel> parentChannel;
+  registrar->GetParentChannel(aLoadIdent, getter_AddRefs(parentChannel));
+  RefPtr<DocumentLoadListener> loadListener = do_QueryObject(parentChannel);
+  registrar->DeregisterChannels(aLoadIdent);
+
+  if (!loadListener) {
+    // The parent went away unexpectedly.
+    *aListener = nullptr;
+    return nullptr;
+  }
+
+  loadListener->mDocumentChannelId = aChannelId;
+
+  MOZ_DIAGNOSTIC_ASSERT(loadListener->mOpenPromise);
+  loadListener.forget(aListener);
+
+  return (*aListener)->mOpenPromise;
+}
+
+void DocumentLoadListener::NotifyDocumentChannelFailed() {
+  LOG(("DocumentLoadListener NotifyDocumentChannelFailed [this=%p]", this));
+  // There's been no calls to ClaimParentLoad, and so no listeners have been
+  // attached to mOpenPromise yet. As such we can run Then() on it.
+  mOpenPromise->Then(
+      GetMainThreadSerialEventTarget(), __func__,
+      [](DocumentLoadListener::OpenPromiseSucceededType&& aResolveValue) {
+        aResolveValue.mPromise->Resolve(NS_BINDING_ABORTED, __func__);
+      },
+      []() {});
+
+  Cancel(NS_BINDING_ABORTED,
+         "DocumentLoadListener::NotifyDocumentChannelFailed"_ns);
+}
+
+void DocumentLoadListener::Disconnect(bool aContinueNavigating) {
+  LOG(("DocumentLoadListener Disconnect [this=%p, aContinueNavigating=%d]",
+       this, aContinueNavigating));
+  // The nsHttpChannel may have a reference to this parent, release it
+  // to avoid circular references.
+  RefPtr<nsHttpChannel> httpChannelImpl = do_QueryObject(mChannel);
+  if (httpChannelImpl) {
+    httpChannelImpl->SetWarningReporter(nullptr);
+    httpChannelImpl->SetEarlyHintObserver(nullptr);
+  }
+
+  // Don't cancel ongoing early hints when continuing to load the web page.
+  // Early hints are loaded earlier in the code and shouldn't get cancelled
+  // here. See also: Bug 1765652
+  if (!aContinueNavigating) {
+    mEarlyHintsService.Cancel("DocumentLoadListener::Disconnect"_ns);
+  }
+
+  if (auto* ctx = GetDocumentBrowsingContext()) {
+    ctx->EndDocumentLoad(aContinueNavigating);
+  }
+}
+
+void DocumentLoadListener::Cancel(const nsresult& aStatusCode,
+                                  const nsACString& aReason) {
+  LOG(
+      ("DocumentLoadListener Cancel [this=%p, "
+       "aStatusCode=%" PRIx32 " ]",
+       this, static_cast<uint32_t>(aStatusCode)));
+  if (mOpenPromiseResolved) {
+    return;
+  }
+  if (mChannel) {
+    mChannel->CancelWithReason(aStatusCode, aReason);
+  }
+
+  DisconnectListeners(aStatusCode, aStatusCode);
+}
+
+void DocumentLoadListener::DisconnectListeners(nsresult aStatus,
+                                               nsresult aLoadGroupStatus,
+                                               bool aContinueNavigating) {
+  LOG(
+      ("DocumentLoadListener DisconnectListener [this=%p, "
+       "aStatus=%" PRIx32 ", aLoadGroupStatus=%" PRIx32
+       ", aContinueNavigating=%d]",
+       this, static_cast<uint32_t>(aStatus),
+       static_cast<uint32_t>(aLoadGroupStatus), aContinueNavigating));
+
+  RejectOpenPromise(aStatus, aLoadGroupStatus, aContinueNavigating, __func__);
+
+  Disconnect(aContinueNavigating);
+
+  // Clear any pending stream filter requests. If we're going to be sending a
+  // response to the content process due to a navigation, our caller will have
+  // already stashed the array to be passed to `TriggerRedirectToRealChannel`,
+  // so it's safe for us to clear here.
+  // TODO: If we retargeted the stream to a non-default handler (e.g. to trigger
+  // a download), we currently never attach a stream filter. Should we attach a
+  // stream filter in those situations as well?
+  mStreamFilterRequests.Clear();
+}
+
+void DocumentLoadListener::RedirectToRealChannelFinished(nsresult aRv) {
+  LOG(
+      ("DocumentLoadListener RedirectToRealChannelFinished [this=%p, "
+       "aRv=%" PRIx32 " ]",
+       this, static_cast<uint32_t>(aRv)));
+  if (NS_FAILED(aRv)) {
+    FinishReplacementChannelSetup(aRv);
+    return;
+  }
+
+  // Wait for background channel ready on target channel
+  nsCOMPtr<nsIRedirectChannelRegistrar> redirectReg =
+      RedirectChannelRegistrar::GetOrCreate();
+  MOZ_ASSERT(redirectReg);
+
+  nsCOMPtr<nsIParentChannel> redirectParentChannel;
+  redirectReg->GetParentChannel(mRedirectChannelId,
+                                getter_AddRefs(redirectParentChannel));
+  if (!redirectParentChannel) {
+    FinishReplacementChannelSetup(NS_ERROR_FAILURE);
+    return;
+  }
+
+  nsCOMPtr<nsIParentRedirectingChannel> redirectingParent =
+      do_QueryInterface(redirectParentChannel);
+  if (!redirectingParent) {
+    // Continue verification procedure if redirecting to non-Http protocol
+    FinishReplacementChannelSetup(NS_OK);
+    return;
+  }
+
+  // Ask redirected channel if verification can proceed.
+  // ReadyToVerify will be invoked when redirected channel is ready.
+  redirectingParent->ContinueVerification(this);
+}
+
+NS_IMETHODIMP
+DocumentLoadListener::ReadyToVerify(nsresult aResultCode) {
+  FinishReplacementChannelSetup(aResultCode);
+  return NS_OK;
+}
+
+void DocumentLoadListener::FinishReplacementChannelSetup(nsresult aResult) {
+  LOG(
+      ("DocumentLoadListener FinishReplacementChannelSetup [this=%p, "
+       "aResult=%x]",
+       this, int(aResult)));
+
+  auto endDocumentLoad = MakeScopeExit([&]() {
+    if (auto* ctx = GetDocumentBrowsingContext()) {
+      ctx->EndDocumentLoad(false);
+    }
+  });
+  mStreamFilterRequests.Clear();
+
+  nsCOMPtr<nsIRedirectChannelRegistrar> registrar =
+      RedirectChannelRegistrar::GetOrCreate();
+  MOZ_ASSERT(registrar);
+
+  nsCOMPtr<nsIParentChannel> redirectChannel;
+  nsresult rv = registrar->GetParentChannel(mRedirectChannelId,
+                                            getter_AddRefs(redirectChannel));
+  if (NS_FAILED(rv) || !redirectChannel) {
+    aResult = NS_ERROR_FAILURE;
+  }
+
+  // Release all previously registered channels, they are no longer needed to
+  // be kept in the registrar from this moment.
+  registrar->DeregisterChannels(mRedirectChannelId);
+  mRedirectChannelId = 0;
+  if (NS_FAILED(aResult)) {
+    if (redirectChannel) {
+      redirectChannel->Delete();
+    }
+    mChannel->Cancel(aResult);
+    mChannel->Resume();
+    return;
+  }
+
+  MOZ_ASSERT(
+      !SameCOMIdentity(redirectChannel, static_cast<nsIParentChannel*>(this)));
+
+  redirectChannel->SetParentListener(mParentChannelListener);
+
+  ApplyPendingFunctions(redirectChannel);
+
+  if (!ResumeSuspendedChannel(redirectChannel)) {
+    nsCOMPtr<nsILoadGroup> loadGroup;
+    mChannel->GetLoadGroup(getter_AddRefs(loadGroup));
+    if (loadGroup) {
+      // We added ourselves to the load group, but attempting
+      // to resume has notified us that the channel is already
+      // finished. Better remove ourselves from the loadgroup
+      // again. The only time the channel will be in a loadgroup
+      // is if we're connected to the parent process.
+      nsresult status = NS_OK;
+      mChannel->GetStatus(&status);
+      loadGroup->RemoveRequest(mChannel, nullptr, status);
+    }
+  }
+}
+
+void DocumentLoadListener::ApplyPendingFunctions(
+    nsIParentChannel* aChannel) const {
+  // We stored the values from all nsIParentChannel functions called since we
+  // couldn't handle them. Copy them across to the real channel since it
+  // should know what to do.
+
+  nsCOMPtr<nsIParentChannel> parentChannel = aChannel;
+  for (const auto& variant : mIParentChannelFunctions) {
+    variant.match(
+        [parentChannel](const ClassifierMatchedInfoParams& aParams) {
+          parentChannel->SetClassifierMatchedInfo(
+              aParams.mList, aParams.mProvider, aParams.mFullHash);
+        },
+        [parentChannel](const ClassifierMatchedTrackingInfoParams& aParams) {
+          parentChannel->SetClassifierMatchedTrackingInfo(aParams.mLists,
+                                                          aParams.mFullHashes);
+        },
+        [parentChannel](const ClassificationFlagsParams& aParams) {
+          parentChannel->NotifyClassificationFlags(aParams.mClassificationFlags,
+                                                   aParams.mIsThirdParty);
+        });
+  }
+
+  RefPtr<HttpChannelSecurityWarningReporter> reporter;
+  if (RefPtr<HttpChannelParent> httpParent = do_QueryObject(aChannel)) {
+    reporter = httpParent;
+  } else if (RefPtr<nsHttpChannel> httpChannel = do_QueryObject(aChannel)) {
+    reporter = httpChannel->GetWarningReporter();
+  }
+  if (reporter) {
+    for (const auto& variant : mSecurityWarningFunctions) {
+      variant.match(
+          [reporter](const ReportSecurityMessageParams& aParams) {
+            Unused << reporter->ReportSecurityMessage(aParams.mMessageTag,
+                                                      aParams.mMessageCategory);
+          },
+          [reporter](const LogBlockedCORSRequestParams& aParams) {
+            Unused << reporter->LogBlockedCORSRequest(
+                aParams.mMessage, aParams.mCategory, aParams.mIsWarning);
+          },
+          [reporter](const LogMimeTypeMismatchParams& aParams) {
+            Unused << reporter->LogMimeTypeMismatch(
+                aParams.mMessageName, aParams.mWarning, aParams.mURL,
+                aParams.mContentType);
+          });
+    }
+  }
+}
+
+bool DocumentLoadListener::ResumeSuspendedChannel(
+    nsIStreamListener* aListener) {
+  LOG(("DocumentLoadListener ResumeSuspendedChannel [this=%p]", this));
+  RefPtr<nsHttpChannel> httpChannel = do_QueryObject(mChannel);
+  if (httpChannel) {
+    httpChannel->SetApplyConversion(mOldApplyConversion);
+  }
+
+  if (!mIsFinished) {
+    mParentChannelListener->SetListenerAfterRedirect(aListener);
+  }
+
+  // If we failed to suspend the channel, then we might have received
+  // some messages while the redirected was being handled.
+  // Manually send them on now.
+  nsTArray<StreamListenerFunction> streamListenerFunctions =
+      std::move(mStreamListenerFunctions);
+  if (!aListener) {
+    streamListenerFunctions.Clear();
+  }
+
+  ForwardStreamListenerFunctions(streamListenerFunctions, aListener);
+
+  // We don't expect to get new stream listener functions added
+  // via re-entrancy. If this ever happens, we should understand
+  // exactly why before allowing it.
+  NS_ASSERTION(mStreamListenerFunctions.IsEmpty(),
+               "Should not have added new stream listener function!");
+
+  mChannel->Resume();
+
+  // Our caller will invoke `EndDocumentLoad` for us.
+
+  return !mIsFinished;
+}
+
+void DocumentLoadListener::CancelEarlyHintPreloads() {
+  mEarlyHintsService.Cancel("DocumentLoadListener::CancelEarlyHintPreloads"_ns);
+}
+
+void DocumentLoadListener::RegisterEarlyHintLinksAndGetConnectArgs(
+    dom::ContentParentId aCpId, nsTArray<EarlyHintConnectArgs>& aOutLinks) {
+  mEarlyHintsService.RegisterLinksAndGetConnectArgs(aCpId, aOutLinks);
+}
+
+void DocumentLoadListener::SerializeRedirectData(
+    RedirectToRealChannelArgs& aArgs, bool aIsCrossProcess,
+    uint32_t aRedirectFlags, uint32_t aLoadFlags, ContentParent* aParent,
+    nsTArray<EarlyHintConnectArgs>&& aEarlyHints,
+    uint32_t aEarlyHintLinkType) const {
+  aArgs.uri() = GetChannelCreationURI();
+  aArgs.loadIdentifier() = mLoadIdentifier;
+  aArgs.earlyHints() = std::move(aEarlyHints);
+  aArgs.earlyHintLinkType() = aEarlyHintLinkType;
+
+  // I previously used HttpBaseChannel::CloneLoadInfoForRedirect, but that
+  // clears the principal to inherit, which fails tests (probably because this
+  // 'redirect' is usually just an implementation detail). It's also http
+  // only, and mChannel can be anything that we redirected to.
+  nsCOMPtr<nsILoadInfo> channelLoadInfo = mChannel->LoadInfo();
+  nsCOMPtr<nsIPrincipal> principalToInherit;
+  channelLoadInfo->GetPrincipalToInherit(getter_AddRefs(principalToInherit));
+
+  const RefPtr<nsHttpChannel> baseChannel = do_QueryObject(mChannel);
+
+  nsCOMPtr<nsILoadContext> loadContext;
+  NS_QueryNotificationCallbacks(mChannel, loadContext);
+  nsCOMPtr<nsILoadInfo> redirectLoadInfo;
+
+  // Only use CloneLoadInfoForRedirect if we have a load context,
+  // since it internally tries to pull OriginAttributes from the
+  // the load context and asserts if they don't match the load info.
+  // We can end up without a load context if the channel has been aborted
+  // and the callbacks have been cleared.
+  if (baseChannel && loadContext) {
+    redirectLoadInfo = baseChannel->CloneLoadInfoForRedirect(
+        aArgs.uri(), nsIChannelEventSink::REDIRECT_INTERNAL);
+    redirectLoadInfo->SetResultPrincipalURI(aArgs.uri());
+
+    // The clone process clears this, and then we fail tests..
+    // docshell/test/mochitest/test_forceinheritprincipal_overrule_owner.html
+    if (principalToInherit) {
+      redirectLoadInfo->SetPrincipalToInherit(principalToInherit);
+    }
+  } else {
+    redirectLoadInfo =
+        static_cast<mozilla::net::LoadInfo*>(channelLoadInfo.get())->Clone();
+
+    redirectLoadInfo->AppendRedirectHistoryEntry(mChannel, true);
+  }
+
+  const Maybe<ClientInfo>& reservedClientInfo =
+      channelLoadInfo->GetReservedClientInfo();
+  if (reservedClientInfo) {
+    redirectLoadInfo->SetReservedClientInfo(*reservedClientInfo);
+  }
+
+  aArgs.registrarId() = mRedirectChannelId;
+
+  MOZ_ALWAYS_SUCCEEDS(
+      ipc::LoadInfoToLoadInfoArgs(redirectLoadInfo, &aArgs.loadInfo()));
+
+  mChannel->GetOriginalURI(getter_AddRefs(aArgs.originalURI()));
+
+  // mChannel can be a nsHttpChannel as well as InterceptedHttpChannel so we
+  // can't use baseChannel here.
+  if (nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(mChannel)) {
+    MOZ_ALWAYS_SUCCEEDS(httpChannel->GetChannelId(&aArgs.channelId()));
+  }
+
+  aArgs.redirectMode() = nsIHttpChannelInternal::REDIRECT_MODE_FOLLOW;
+  nsCOMPtr<nsIHttpChannelInternal> httpChannelInternal =
+      do_QueryInterface(mChannel);
+  if (httpChannelInternal) {
+    MOZ_ALWAYS_SUCCEEDS(
+        httpChannelInternal->GetRedirectMode(&aArgs.redirectMode()));
+  }
+
+  if (baseChannel) {
+    aArgs.init() =
+        Some(baseChannel
+                 ->CloneReplacementChannelConfig(
+                     true, aRedirectFlags,
+                     HttpBaseChannel::ReplacementReason::DocumentChannel)
+                 .Serialize(aParent));
+  }
+
+  uint32_t contentDispositionTemp;
+  nsresult rv = mChannel->GetContentDisposition(&contentDispositionTemp);
+  if (NS_SUCCEEDED(rv)) {
+    aArgs.contentDisposition() = Some(contentDispositionTemp);
+  }
+
+  nsString contentDispositionFilenameTemp;
+  rv = mChannel->GetContentDispositionFilename(contentDispositionFilenameTemp);
+  if (NS_SUCCEEDED(rv)) {
+    aArgs.contentDispositionFilename() = Some(contentDispositionFilenameTemp);
+  }
+
+  SetNeedToAddURIVisit(mChannel, false);
+
+  aArgs.newLoadFlags() = aLoadFlags;
+  aArgs.redirectFlags() = aRedirectFlags;
+  aArgs.properties() = do_QueryObject(mChannel);
+  aArgs.srcdocData() = mSrcdocData;
+  aArgs.baseUri() = mBaseURI;
+  aArgs.loadStateExternalLoadFlags() = mLoadStateExternalLoadFlags;
+  aArgs.loadStateInternalLoadFlags() = mLoadStateInternalLoadFlags;
+  aArgs.loadStateLoadType() = mLoadStateLoadType;
+  aArgs.originalUriString() = mOriginalUriString;
+  if (mLoadingSessionHistoryInfo) {
+    aArgs.loadingSessionHistoryInfo().emplace(*mLoadingSessionHistoryInfo);
+  }
+}
+
+static bool IsFirstLoadInWindow(nsIChannel* aChannel) {
+  if (nsCOMPtr<nsIPropertyBag2> props = do_QueryInterface(aChannel)) {
+    bool tmp = false;
+    nsresult rv =
+        props->GetPropertyAsBool(u"docshell.newWindowTarget"_ns, &tmp);
+    return NS_SUCCEEDED(rv) && tmp;
+  }
+  return false;
+}
+
+// Get where the document loaded by this nsIChannel should be rendered. This
+// will be `OPEN_CURRENTWINDOW` unless we're loading an attachment which would
+// normally open in an external program, but we're instead choosing to render
+// internally.
+static int32_t GetWhereToOpen(nsIChannel* aChannel, bool aIsDocumentLoad) {
+  // Ignore content disposition for loads from an object or embed element.
+  if (!aIsDocumentLoad) {
+    return nsIBrowserDOMWindow::OPEN_CURRENTWINDOW;
+  }
+
+  // Always continue in the same window if we're not loading an attachment.
+  uint32_t disposition = nsIChannel::DISPOSITION_INLINE;
+  if (NS_FAILED(aChannel->GetContentDisposition(&disposition)) ||
+      disposition != nsIChannel::DISPOSITION_ATTACHMENT) {
+    return nsIBrowserDOMWindow::OPEN_CURRENTWINDOW;
+  }
+
+  // If the channel is for a new window target, continue in the same window.
+  if (IsFirstLoadInWindow(aChannel)) {
+    return nsIBrowserDOMWindow::OPEN_CURRENTWINDOW;
+  }
+
+  // Respect the user's preferences with browser.link.open_newwindow
+  // FIXME: There should probably be a helper for this, as the logic is
+  // duplicated in a few places.
+  int32_t where = Preferences::GetInt("browser.link.open_newwindow",
+                                      nsIBrowserDOMWindow::OPEN_NEWTAB);
+  if (where == nsIBrowserDOMWindow::OPEN_CURRENTWINDOW ||
+      where == nsIBrowserDOMWindow::OPEN_NEWWINDOW ||
+      where == nsIBrowserDOMWindow::OPEN_NEWTAB) {
+    return where;
+  }
+  return nsIBrowserDOMWindow::OPEN_NEWTAB;
+}
+
+static DocumentLoadListener::ProcessBehavior GetProcessSwitchBehavior(
+    Element* aBrowserElement) {
+  if (aBrowserElement->HasAttribute(u"maychangeremoteness"_ns)) {
+    return DocumentLoadListener::ProcessBehavior::PROCESS_BEHAVIOR_STANDARD;
+  }
+  nsCOMPtr<nsIBrowser> browser = aBrowserElement->AsBrowser();
+  bool isRemoteBrowser = false;
+  browser->GetIsRemoteBrowser(&isRemoteBrowser);
+  if (isRemoteBrowser) {
+    return DocumentLoadListener::ProcessBehavior::
+        PROCESS_BEHAVIOR_SUBFRAME_ONLY;
+  }
+  return DocumentLoadListener::ProcessBehavior::PROCESS_BEHAVIOR_DISABLED;
+}
+
+static bool ContextCanProcessSwitch(CanonicalBrowsingContext* aBrowsingContext,
+                                    WindowGlobalParent* aParentWindow,
+                                    bool aSwitchToNewTab) {
+  if (NS_WARN_IF(!aBrowsingContext)) {
+    MOZ_LOG(gProcessIsolationLog, LogLevel::Warning,
+            ("Process Switch Abort: no browsing context"));
+    return false;
+  }
+  if (!aBrowsingContext->IsContent()) {
+    MOZ_LOG(gProcessIsolationLog, LogLevel::Warning,
+            ("Process Switch Abort: non-content browsing context"));
+    return false;
+  }
+
+  // If we're switching into a new tab, we can skip the remaining checks, as
+  // we're not actually changing the process of aBrowsingContext, so whether or
+  // not it is allowed to process switch isn't relevant.
+  if (aSwitchToNewTab) {
+    return true;
+  }
+
+  if (aParentWindow && !aBrowsingContext->UseRemoteSubframes()) {
+    MOZ_LOG(gProcessIsolationLog, LogLevel::Warning,
+            ("Process Switch Abort: remote subframes disabled"));
+    return false;
+  }
+
+  if (aParentWindow && aParentWindow->IsInProcess()) {
+    MOZ_LOG(gProcessIsolationLog, LogLevel::Warning,
+            ("Process Switch Abort: Subframe with in-process parent"));
+    return false;
+  }
+
+  // Determine what process switching behaviour is being requested by the root
+  // <browser> element.
+  Element* browserElement = aBrowsingContext->Top()->GetEmbedderElement();
+  if (!browserElement) {
+    MOZ_LOG(gProcessIsolationLog, LogLevel::Warning,
+            ("Process Switch Abort: cannot get embedder element"));
+    return false;
+  }
+  nsCOMPtr<nsIBrowser> browser = browserElement->AsBrowser();
+  if (!browser) {
+    MOZ_LOG(gProcessIsolationLog, LogLevel::Warning,
+            ("Process Switch Abort: not loaded within nsIBrowser"));
+    return false;
+  }
+
+  DocumentLoadListener::ProcessBehavior processBehavior =
+      GetProcessSwitchBehavior(browserElement);
+
+  // Check if the process switch we're considering is disabled by the
+  // <browser>'s process behavior.
+  if (processBehavior ==
+      DocumentLoadListener::ProcessBehavior::PROCESS_BEHAVIOR_DISABLED) {
+    MOZ_LOG(gProcessIsolationLog, LogLevel::Warning,
+            ("Process Switch Abort: switch disabled by <browser>"));
+    return false;
+  }
+  if (!aParentWindow && processBehavior ==
+                            DocumentLoadListener::ProcessBehavior::
+                                PROCESS_BEHAVIOR_SUBFRAME_ONLY) {
+    MOZ_LOG(gProcessIsolationLog, LogLevel::Warning,
+            ("Process Switch Abort: toplevel switch disabled by <browser>"));
+    return false;
+  }
+
+  return true;
+}
+
+static RefPtr<dom::BrowsingContextCallbackReceivedPromise> SwitchToNewTab(
+    CanonicalBrowsingContext* aLoadingBrowsingContext, int32_t aWhere) {
+  MOZ_ASSERT(aWhere == nsIBrowserDOMWindow::OPEN_NEWTAB ||
+                 aWhere == nsIBrowserDOMWindow::OPEN_NEWWINDOW,
+             "Unsupported open location");
+
+  auto promise =
+      MakeRefPtr<dom::BrowsingContextCallbackReceivedPromise::Private>(
+          __func__);
+
+  // Get the nsIBrowserDOMWindow for the given BrowsingContext's tab.
+  nsCOMPtr<nsIBrowserDOMWindow> browserDOMWindow =
+      aLoadingBrowsingContext->GetBrowserDOMWindow();
+  if (NS_WARN_IF(!browserDOMWindow)) {
+    MOZ_LOG(gProcessIsolationLog, LogLevel::Warning,
+            ("Process Switch Abort: Unable to get nsIBrowserDOMWindow"));
+    promise->Reject(NS_ERROR_FAILURE, __func__);
+    return promise;
+  }
+
+  // Open a new content tab by calling into frontend. We don't need to worry
+  // about the triggering principal or CSP, as createContentWindow doesn't
+  // actually start loading anything, but use a null principal anyway in case
+  // something changes.
+  nsCOMPtr<nsIPrincipal> triggeringPrincipal =
+      NullPrincipal::Create(aLoadingBrowsingContext->OriginAttributesRef());
+
+  RefPtr<nsOpenWindowInfo> openInfo = new nsOpenWindowInfo();
+  openInfo->mBrowsingContextReadyCallback =
+      new nsBrowsingContextReadyCallback(promise);
+  openInfo->mOriginAttributes = aLoadingBrowsingContext->OriginAttributesRef();
+  openInfo->mParent = aLoadingBrowsingContext;
+  openInfo->mForceNoOpener = true;
+  openInfo->mIsRemote = true;
+
+  // Do the actual work to open a new tab or window async.
+  nsresult rv = NS_DispatchToMainThread(NS_NewRunnableFunction(
+      "DocumentLoadListener::SwitchToNewTab",
+      [browserDOMWindow, openInfo, aWhere, triggeringPrincipal, promise] {
+        RefPtr<BrowsingContext> bc;
+        nsresult rv = browserDOMWindow->CreateContentWindow(
+            /* uri */ nullptr, openInfo, aWhere,
+            nsIBrowserDOMWindow::OPEN_NO_REFERRER, triggeringPrincipal,
+            /* csp */ nullptr, getter_AddRefs(bc));
+        if (NS_WARN_IF(NS_FAILED(rv))) {
+          MOZ_LOG(gProcessIsolationLog, LogLevel::Warning,
+                  ("Process Switch Abort: CreateContentWindow threw"));
+          promise->Reject(rv, __func__);
+        }
+        if (bc) {
+          promise->Resolve(bc, __func__);
+        }
+      }));
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    promise->Reject(NS_ERROR_UNEXPECTED, __func__);
+  }
+  return promise;
+}
+
+bool DocumentLoadListener::MaybeTriggerProcessSwitch(
+    bool* aWillSwitchToRemote) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_DIAGNOSTIC_ASSERT(mChannel);
+  MOZ_DIAGNOSTIC_ASSERT(mParentChannelListener);
+  MOZ_DIAGNOSTIC_ASSERT(aWillSwitchToRemote);
+
+  MOZ_LOG(gProcessIsolationLog, LogLevel::Verbose,
+          ("DocumentLoadListener MaybeTriggerProcessSwitch [this=%p, uri=%s, "
+           "browserid=%" PRIx64 "]",
+           this, GetChannelCreationURI()->GetSpecOrDefault().get(),
+           GetLoadingBrowsingContext()->Top()->BrowserId()));
+
+  // If we're doing an <object>/<embed> load, we may be doing a document load at
+  // this point. We never need to do a process switch for a non-document
+  // <object> or <embed> load.
+  if (!mIsDocumentLoad) {
+    if (!mChannel->IsDocument()) {
+      MOZ_LOG(gProcessIsolationLog, LogLevel::Verbose,
+              ("Process Switch Abort: non-document load"));
+      return false;
+    }
+    nsresult status;
+    if (!nsObjectLoadingContent::IsSuccessfulRequest(mChannel, &status)) {
+      MOZ_LOG(gProcessIsolationLog, LogLevel::Verbose,
+              ("Process Switch Abort: error page"));
+      return false;
+    }
+  }
+
+  // Check if we should handle this load in a different tab or window.
+  int32_t where = GetWhereToOpen(mChannel, mIsDocumentLoad);
+  bool switchToNewTab = where != nsIBrowserDOMWindow::OPEN_CURRENTWINDOW;
+
+  // Get the loading BrowsingContext. This may not be the context which will be
+  // switching processes when switching to a new tab, and in the case of an
+  // <object> or <embed> element, as we don't create the final context until
+  // after process selection.
+  //
+  // - /!\ WARNING /!\ -
+  // Don't use `browsingContext->IsTop()` in this method! It will behave
+  // incorrectly for non-document loads such as `<object>` or `<embed>`.
+  // Instead, check whether or not `parentWindow` is null.
+  RefPtr<CanonicalBrowsingContext> browsingContext =
+      GetLoadingBrowsingContext();
+  // If switching to a new tab, the final BC isn't a frame.
+  RefPtr<WindowGlobalParent> parentWindow =
+      switchToNewTab ? nullptr : GetParentWindowContext();
+  if (!ContextCanProcessSwitch(browsingContext, parentWindow, switchToNewTab)) {
+    return false;
+  }
+
+  if (!browsingContext->IsOwnedByProcess(GetContentProcessId(mContentParent))) {
+    MOZ_LOG(gProcessIsolationLog, LogLevel::Error,
+            ("Process Switch Abort: context no longer owned by creator"));
+    Cancel(NS_BINDING_ABORTED,
+           "Process Switch Abort: context no longer owned by creator"_ns);
+    return false;
+  }
+
+  if (browsingContext->IsReplaced()) {
+    MOZ_LOG(gProcessIsolationLog, LogLevel::Warning,
+            ("Process Switch Abort: replaced browsing context"));
+    Cancel(NS_BINDING_ABORTED,
+           "Process Switch Abort: replaced browsing context"_ns);
+    return false;
+  }
+
+  nsAutoCString currentRemoteType(NOT_REMOTE_TYPE);
+  if (mContentParent) {
+    currentRemoteType = mContentParent->GetRemoteType();
+  }
+
+  auto optionsResult = IsolationOptionsForNavigation(
+      browsingContext->Top(), switchToNewTab ? nullptr : parentWindow.get(),
+      GetChannelCreationURI(), mChannel, currentRemoteType,
+      HasCrossOriginOpenerPolicyMismatch(), switchToNewTab, mLoadStateLoadType,
+      mDocumentChannelId, mRemoteTypeOverride);
+  if (optionsResult.isErr()) {
+    MOZ_LOG(gProcessIsolationLog, LogLevel::Error,
+            ("Process Switch Abort: CheckIsolationForNavigation Failed with %s",
+             GetStaticErrorName(optionsResult.inspectErr())));
+    Cancel(optionsResult.unwrapErr(),
+           "Process Switch Abort: CheckIsolationForNavigation Failed"_ns);
+    return false;
+  }
+
+  NavigationIsolationOptions options = optionsResult.unwrap();
+
+  if (options.mTryUseBFCache) {
+    MOZ_ASSERT(!parentWindow, "Can only BFCache toplevel windows");
+    MOZ_ASSERT(!switchToNewTab, "Can't BFCache for a tab switch");
+    bool sameOrigin = false;
+    if (auto* wgp = browsingContext->GetCurrentWindowGlobal()) {
+      nsCOMPtr<nsIPrincipal> resultPrincipal;
+      MOZ_ALWAYS_SUCCEEDS(
+          nsContentUtils::GetSecurityManager()->GetChannelResultPrincipal(
+              mChannel, getter_AddRefs(resultPrincipal)));
+      sameOrigin =
+          wgp->DocumentPrincipal()->EqualsConsideringDomain(resultPrincipal);
+    }
+
+    // We only reset the window name for content.
+    mLoadingSessionHistoryInfo->mForceMaybeResetName.emplace(
+        StaticPrefs::privacy_window_name_update_enabled() &&
+        browsingContext->IsContent() && !sameOrigin);
+  }
+
+  MOZ_LOG(
+      gProcessIsolationLog, LogLevel::Verbose,
+      ("CheckIsolationForNavigation -> current:(%s) remoteType:(%s) replace:%d "
+       "group:%" PRIx64 " bfcache:%d shentry:%p newTab:%d",
+       currentRemoteType.get(), options.mRemoteType.get(),
+       options.mReplaceBrowsingContext, options.mSpecificGroupId,
+       options.mTryUseBFCache, options.mActiveSessionHistoryEntry.get(),
+       switchToNewTab));
+
+  // Check if a process switch is needed.
+  if (currentRemoteType == options.mRemoteType &&
+      !options.mReplaceBrowsingContext && !switchToNewTab) {
+    MOZ_LOG(gProcessIsolationLog, LogLevel::Info,
+            ("Process Switch Abort: type (%s) is compatible",
+             options.mRemoteType.get()));
+    return false;
+  }
+
+  if (NS_WARN_IF(parentWindow && options.mRemoteType.IsEmpty())) {
+    MOZ_LOG(gProcessIsolationLog, LogLevel::Error,
+            ("Process Switch Abort: non-remote target process for subframe"));
+    return false;
+  }
+
+  *aWillSwitchToRemote = !options.mRemoteType.IsEmpty();
+
+  // If we've decided to re-target this load into a new tab or window (see
+  // `GetWhereToOpen`), do so before performing a process switch. This will
+  // require creating the new <browser> to load in, which may be performed
+  // async.
+  if (switchToNewTab) {
+    SwitchToNewTab(browsingContext, where)
+        ->Then(
+            GetMainThreadSerialEventTarget(), __func__,
+            [self = RefPtr{this},
+             options](const RefPtr<BrowsingContext>& aBrowsingContext) mutable {
+              if (aBrowsingContext->IsDiscarded()) {
+                MOZ_LOG(
+                    gProcessIsolationLog, LogLevel::Error,
+                    ("Process Switch: Got invalid new-tab BrowsingContext"));
+                self->RedirectToRealChannelFinished(NS_ERROR_FAILURE);
+                return;
+              }
+
+              MOZ_LOG(gProcessIsolationLog, LogLevel::Verbose,
+                      ("Process Switch: Redirected load to new tab"));
+              self->TriggerProcessSwitch(aBrowsingContext->Canonical(), options,
+                                         /* aIsNewTab */ true);
+            },
+            [self = RefPtr{this}](const CopyableErrorResult&) {
+              MOZ_LOG(gProcessIsolationLog, LogLevel::Error,
+                      ("Process Switch: SwitchToNewTab failed"));
+              self->RedirectToRealChannelFinished(NS_ERROR_FAILURE);
+            });
+    return true;
+  }
+
+  // If we're doing a document load, we can immediately perform a process
+  // switch.
+  if (mIsDocumentLoad) {
+    TriggerProcessSwitch(browsingContext, options);
+    return true;
+  }
+
+  // We're not doing a document load, which means we must be performing an
+  // object load. We need a BrowsingContext to perform the switch in, so will
+  // trigger an upgrade.
+  if (!mObjectUpgradeHandler) {
+    MOZ_LOG(gProcessIsolationLog, LogLevel::Warning,
+            ("Process Switch Abort: no object upgrade handler"));
+    return false;
+  }
+
+  if (!StaticPrefs::fission_remoteObjectEmbed()) {
+    MOZ_LOG(gProcessIsolationLog, LogLevel::Verbose,
+            ("Process Switch Abort: remote <object>/<embed> disabled"));
+    return false;
+  }
+
+  mObjectUpgradeHandler->UpgradeObjectLoad()->Then(
+      GetMainThreadSerialEventTarget(), __func__,
+      [self = RefPtr{this}, options, parentWindow](
+          const RefPtr<CanonicalBrowsingContext>& aBrowsingContext) mutable {
+        if (aBrowsingContext->IsDiscarded() ||
+            parentWindow != aBrowsingContext->GetParentWindowContext()) {
+          MOZ_LOG(gProcessIsolationLog, LogLevel::Error,
+                  ("Process Switch: Got invalid BrowsingContext from object "
+                   "upgrade!"));
+          self->RedirectToRealChannelFinished(NS_ERROR_FAILURE);
+          return;
+        }
+
+        MOZ_LOG(gProcessIsolationLog, LogLevel::Verbose,
+                ("Process Switch: Upgraded Object to Document Load"));
+        self->TriggerProcessSwitch(aBrowsingContext, options);
+      },
+      [self = RefPtr{this}](nsresult aStatusCode) {
+        MOZ_ASSERT(NS_FAILED(aStatusCode), "Status should be error");
+        self->RedirectToRealChannelFinished(aStatusCode);
+      });
+  return true;
+}
+
+void DocumentLoadListener::TriggerProcessSwitch(
+    CanonicalBrowsingContext* aContext,
+    const NavigationIsolationOptions& aOptions, bool aIsNewTab) {
+  MOZ_DIAGNOSTIC_ASSERT(aIsNewTab || aContext->IsOwnedByProcess(
+                                         GetContentProcessId(mContentParent)),
+                        "not owned by creator process anymore?");
+  if (MOZ_LOG_TEST(gProcessIsolationLog, LogLevel::Info)) {
+    nsCString currentRemoteType = "INVALID"_ns;
+    aContext->GetCurrentRemoteType(currentRemoteType, IgnoreErrors());
+
+    MOZ_LOG(gProcessIsolationLog, LogLevel::Info,
+            ("Process Switch: Changing Remoteness from '%s' to '%s'",
+             currentRemoteType.get(), aOptions.mRemoteType.get()));
+  }
+
+  // Stash our stream filter requests to pass to TriggerRedirectToRealChannel,
+  // as the call to `DisconnectListeners` will clear our list.
+  nsTArray<StreamFilterRequest> streamFilterRequests =
+      std::move(mStreamFilterRequests);
+
+  // We're now committing to a process switch, so we can disconnect from
+  // the listeners in the old process.
+  // As the navigation is continuing, we don't actually want to cancel the
+  // request in the old process unless we're redirecting the load into a new
+  // tab.
+  DisconnectListeners(NS_BINDING_ABORTED, NS_BINDING_ABORTED, !aIsNewTab);
+
+  MOZ_LOG(gProcessIsolationLog, LogLevel::Verbose,
+          ("Process Switch: Calling ChangeRemoteness"));
+  aContext->ChangeRemoteness(aOptions, mLoadIdentifier)
+      ->Then(
+          GetMainThreadSerialEventTarget(), __func__,
+          [self = RefPtr{this}, requests = std::move(streamFilterRequests)](
+              BrowserParent* aBrowserParent) mutable {
+            MOZ_ASSERT(self->mChannel,
+                       "Something went wrong, channel got cancelled");
+            self->TriggerRedirectToRealChannel(
+                Some(aBrowserParent ? aBrowserParent->Manager() : nullptr),
+                std::move(requests));
+          },
+          [self = RefPtr{this}](nsresult aStatusCode) {
+            MOZ_ASSERT(NS_FAILED(aStatusCode), "Status should be error");
+            self->RedirectToRealChannelFinished(aStatusCode);
+          });
+}
+
+RefPtr<PDocumentChannelParent::RedirectToRealChannelPromise>
+DocumentLoadListener::RedirectToParentProcess(uint32_t aRedirectFlags,
+                                              uint32_t aLoadFlags) {
+  // This is largely the same as ContentChild::RecvCrossProcessRedirect,
+  // except without needing to deserialize or create an nsIChildChannel.
+
+  RefPtr<nsDocShellLoadState> loadState;
+  nsDocShellLoadState::CreateFromPendingChannel(
+      mChannel, mLoadIdentifier, mRedirectChannelId, getter_AddRefs(loadState));
+
+  loadState->SetLoadFlags(mLoadStateExternalLoadFlags);
+  loadState->SetInternalLoadFlags(mLoadStateInternalLoadFlags);
+  loadState->SetLoadType(mLoadStateLoadType);
+  if (mLoadingSessionHistoryInfo) {
+    loadState->SetLoadingSessionHistoryInfo(*mLoadingSessionHistoryInfo);
+  }
+
+  // This is poorly named now.
+  RefPtr<ChildProcessChannelListener> processListener =
+      ChildProcessChannelListener::GetSingleton();
+
+  auto promise =
+      MakeRefPtr<PDocumentChannelParent::RedirectToRealChannelPromise::Private>(
+          __func__);
+  promise->UseDirectTaskDispatch(__func__);
+  auto resolve = [promise](nsresult aResult) {
+    promise->Resolve(aResult, __func__);
+  };
+
+  nsTArray<ipc::Endpoint<extensions::PStreamFilterParent>> endpoints;
+  processListener->OnChannelReady(loadState, mLoadIdentifier,
+                                  std::move(endpoints), mTiming,
+                                  std::move(resolve));
+
+  return promise;
+}
+
+RefPtr<PDocumentChannelParent::RedirectToRealChannelPromise>
+DocumentLoadListener::RedirectToRealChannel(
+    uint32_t aRedirectFlags, uint32_t aLoadFlags,
+    const Maybe<ContentParent*>& aDestinationProcess,
+    nsTArray<ParentEndpoint>&& aStreamFilterEndpoints) {
+  LOG(
+      ("DocumentLoadListener RedirectToRealChannel [this=%p] "
+       "aRedirectFlags=%" PRIx32 ", aLoadFlags=%" PRIx32,
+       this, aRedirectFlags, aLoadFlags));
+
+  if (mIsDocumentLoad) {
+    // TODO(djg): Add the last URI visit to history if success. Is there a
+    // better place to handle this? Need access to the updated aLoadFlags.
+    nsresult status = NS_OK;
+    mChannel->GetStatus(&status);
+    bool updateGHistory =
+        nsDocShell::ShouldUpdateGlobalHistory(mLoadStateLoadType);
+    if (NS_SUCCEEDED(status) && updateGHistory &&
+        !net::ChannelIsPost(mChannel)) {
+      AddURIVisit(mChannel, aLoadFlags);
+    }
+  }
+
+  // Register the new channel and obtain id for it
+  nsCOMPtr<nsIRedirectChannelRegistrar> registrar =
+      RedirectChannelRegistrar::GetOrCreate();
+  MOZ_ASSERT(registrar);
+  nsCOMPtr<nsIChannel> chan = mChannel;
+  if (nsCOMPtr<nsIViewSourceChannel> vsc = do_QueryInterface(chan)) {
+    chan = vsc->GetInnerChannel();
+  }
+  mRedirectChannelId = nsContentUtils::GenerateLoadIdentifier();
+  MOZ_ALWAYS_SUCCEEDS(registrar->RegisterChannel(chan, mRedirectChannelId));
+
+  if (aDestinationProcess) {
+    RefPtr<ContentParent> cp = *aDestinationProcess;
+    if (!cp) {
+      MOZ_ASSERT(aStreamFilterEndpoints.IsEmpty());
+      return RedirectToParentProcess(aRedirectFlags, aLoadFlags);
+    }
+
+    if (!cp->CanSend()) {
+      return PDocumentChannelParent::RedirectToRealChannelPromise::
+          CreateAndReject(ipc::ResponseRejectReason::SendError, __func__);
+    }
+
+    nsTArray<EarlyHintConnectArgs> ehArgs;
+    mEarlyHintsService.RegisterLinksAndGetConnectArgs(cp->ChildID(), ehArgs);
+
+    RedirectToRealChannelArgs args;
+    SerializeRedirectData(args, /* aIsCrossProcess */ true, aRedirectFlags,
+                          aLoadFlags, cp, std::move(ehArgs),
+                          mEarlyHintsService.LinkType());
+    if (mTiming) {
+      mTiming->Anonymize(args.uri());
+      args.timing() = std::move(mTiming);
+    }
+
+    auto loadInfo = args.loadInfo();
+
+    if (loadInfo.isNothing()) {
+      return PDocumentChannelParent::RedirectToRealChannelPromise::
+          CreateAndReject(ipc::ResponseRejectReason::SendError, __func__);
+    }
+
+    cp->TransmitBlobDataIfBlobURL(args.uri());
+
+    if (CanonicalBrowsingContext* bc = GetDocumentBrowsingContext()) {
+      if (bc->IsTop() && bc->IsActive()) {
+        nsContentUtils::RequestGeckoTaskBurst();
+      }
+    }
+
+    return cp->SendCrossProcessRedirect(args,
+                                        std::move(aStreamFilterEndpoints));
+  }
+
+  if (mOpenPromiseResolved) {
+    LOG(
+        ("DocumentLoadListener RedirectToRealChannel [this=%p] "
+         "promise already resolved. Aborting.",
+         this));
+    // The promise has already been resolved or aborted, so we have no way to
+    // return a promise again to the listener which would cancel the operation.
+    // Reject the promise immediately.
+    return PDocumentChannelParent::RedirectToRealChannelPromise::
+        CreateAndResolve(NS_BINDING_ABORTED, __func__);
+  }
+
+  // This promise will be passed on the promise listener which will
+  // resolve this promise for us.
+  auto promise =
+      MakeRefPtr<PDocumentChannelParent::RedirectToRealChannelPromise::Private>(
+          __func__);
+
+  mOpenPromise->Resolve(
+      OpenPromiseSucceededType({std::move(aStreamFilterEndpoints),
+                                aRedirectFlags, aLoadFlags,
+                                mEarlyHintsService.LinkType(), promise}),
+      __func__);
+
+  // There is no way we could come back here if the promise had been resolved
+  // previously. But for clarity and to avoid all doubt, we set this boolean to
+  // true.
+  mOpenPromiseResolved = true;
+
+  return promise;
+}
+
+void DocumentLoadListener::TriggerRedirectToRealChannel(
+    const Maybe<ContentParent*>& aDestinationProcess,
+    nsTArray<StreamFilterRequest> aStreamFilterRequests) {
+  LOG((
+      "DocumentLoadListener::TriggerRedirectToRealChannel [this=%p] "
+      "aDestinationProcess=%" PRId64,
+      this, aDestinationProcess ? int64_t(*aDestinationProcess) : int64_t(-1)));
+  // This initiates replacing the current DocumentChannel with a
+  // protocol specific 'real' channel, maybe in a different process than
+  // the current DocumentChannelChild, if aDestinationProces is set.
+  // It registers the current mChannel with the registrar to get an ID
+  // so that the remote end can setup a new IPDL channel and lookup
+  // the same underlying channel.
+  // We expect this process to finish with FinishReplacementChannelSetup
+  // (for both in-process and process switch cases), where we cleanup
+  // the registrar and copy across any needed state to the replacing
+  // IPDL parent object.
+
+  nsTArray<ParentEndpoint> parentEndpoints(aStreamFilterRequests.Length());
+  if (!aStreamFilterRequests.IsEmpty()) {
+    ContentParent* cp = aDestinationProcess.valueOr(mContentParent);
+    base::ProcessId pid = cp ? cp->OtherPid() : base::ProcessId{0};
+
+    for (StreamFilterRequest& request : aStreamFilterRequests) {
+      if (!pid) {
+        request.mPromise->Reject(false, __func__);
+        request.mPromise = nullptr;
+        continue;
+      }
+      ParentEndpoint parent;
+      nsresult rv = extensions::PStreamFilter::CreateEndpoints(
+          &parent, &request.mChildEndpoint);
+
+      if (NS_FAILED(rv)) {
+        request.mPromise->Reject(false, __func__);
+        request.mPromise = nullptr;
+      } else {
+        parentEndpoints.AppendElement(std::move(parent));
+      }
+    }
+  }
+
+  // If we didn't have any redirects, then we pass the REDIRECT_INTERNAL flag
+  // for this channel switch so that it isn't recorded in session history etc.
+  // If there were redirect(s), then we want this switch to be recorded as a
+  // real one, since we have a new URI.
+  uint32_t redirectFlags = 0;
+  if (!mHaveVisibleRedirect) {
+    redirectFlags = nsIChannelEventSink::REDIRECT_INTERNAL;
+  }
+
+  uint32_t newLoadFlags = nsIRequest::LOAD_NORMAL;
+  MOZ_ALWAYS_SUCCEEDS(mChannel->GetLoadFlags(&newLoadFlags));
+  // We're pulling our flags from the inner channel, which may not have this
+  // flag set on it. This is the case when loading a 'view-source' channel.
+  if (mIsDocumentLoad || aDestinationProcess) {
+    newLoadFlags |= nsIChannel::LOAD_DOCUMENT_URI;
+  }
+  if (!aDestinationProcess) {
+    newLoadFlags |= nsIChannel::LOAD_REPLACE;
+  }
+
+  // INHIBIT_PERSISTENT_CACHING is clearing during http redirects (from
+  // both parent and content process channel instances), but only ever
+  // re-added to the parent-side nsHttpChannel.
+  // To match that behaviour, we want to explicitly avoid copying this flag
+  // back to our newly created content side channel, otherwise it can
+  // affect sub-resources loads in the same load group.
+  nsCOMPtr<nsIURI> uri;
+  mChannel->GetURI(getter_AddRefs(uri));
+  if (uri && uri->SchemeIs("https")) {
+    newLoadFlags &= ~nsIRequest::INHIBIT_PERSISTENT_CACHING;
+  }
+
+  RefPtr<DocumentLoadListener> self = this;
+  RedirectToRealChannel(redirectFlags, newLoadFlags, aDestinationProcess,
+                        std::move(parentEndpoints))
+      ->Then(
+          GetCurrentSerialEventTarget(), __func__,
+          [self, requests = std::move(aStreamFilterRequests)](
+              const nsresult& aResponse) mutable {
+            for (StreamFilterRequest& request : requests) {
+              if (request.mPromise) {
+                request.mPromise->Resolve(std::move(request.mChildEndpoint),
+                                          __func__);
+                request.mPromise = nullptr;
+              }
+            }
+            self->RedirectToRealChannelFinished(aResponse);
+          },
+          [self](const mozilla::ipc::ResponseRejectReason) {
+            self->RedirectToRealChannelFinished(NS_ERROR_FAILURE);
+          });
+}
+
+void DocumentLoadListener::MaybeReportBlockedByURLClassifier(nsresult aStatus) {
+  auto* browsingContext = GetDocumentBrowsingContext();
+  if (!browsingContext || browsingContext->IsTop() ||
+      !StaticPrefs::privacy_trackingprotection_testing_report_blocked_node()) {
+    return;
+  }
+
+  if (!UrlClassifierFeatureFactory::IsClassifierBlockingErrorCode(aStatus)) {
+    return;
+  }
+
+  RefPtr<WindowGlobalParent> parent = browsingContext->GetParentWindowContext();
+  if (parent) {
+    Unused << parent->SendAddBlockedFrameNodeByClassifier(browsingContext);
+  }
+}
+
+bool DocumentLoadListener::DocShellWillDisplayContent(nsresult aStatus) {
+  if (NS_SUCCEEDED(aStatus)) {
+    return true;
+  }
+
+  // Always return errored loads to the <object> or <embed> element's process,
+  // as load errors will not be rendered as documents.
+  if (!mIsDocumentLoad) {
+    return false;
+  }
+
+  // nsDocShell attempts urifixup on some failure types,
+  // but also of those also display an error page if we don't
+  // succeed with fixup, so we don't need to check for it
+  // here.
+
+  auto* loadingContext = GetLoadingBrowsingContext();
+
+  bool isInitialDocument = true;
+  if (WindowGlobalParent* currentWindow =
+          loadingContext->GetCurrentWindowGlobal()) {
+    isInitialDocument = currentWindow->IsInitialDocument();
+  }
+
+  nsresult rv = nsDocShell::FilterStatusForErrorPage(
+      aStatus, mChannel, mLoadStateLoadType, loadingContext->IsTop(),
+      loadingContext->GetUseErrorPages(), isInitialDocument, nullptr);
+
+  if (NS_SUCCEEDED(rv)) {
+    MOZ_LOG(gProcessIsolationLog, LogLevel::Verbose,
+            ("Skipping process switch, as DocShell will not display content "
+             "(status: %s) %s",
+             GetStaticErrorName(aStatus),
+             GetChannelCreationURI()->GetSpecOrDefault().get()));
+  }
+
+  // If filtering returned a failure code, then an error page will
+  // be display for that code, so return true;
+  return NS_FAILED(rv);
+}
+
+bool DocumentLoadListener::MaybeHandleLoadErrorWithURIFixup(nsresult aStatus) {
+  RefPtr<CanonicalBrowsingContext> bc = GetDocumentBrowsingContext();
+  if (!bc) {
+    return false;
+  }
+
+  nsCOMPtr<nsIInputStream> newPostData;
+  nsCOMPtr<nsIURI> newURI = nsDocShell::AttemptURIFixup(
+      mChannel, aStatus, mOriginalUriString, mLoadStateLoadType, bc->IsTop(),
+      mLoadStateInternalLoadFlags &
+          nsDocShell::INTERNAL_LOAD_FLAGS_ALLOW_THIRD_PARTY_FIXUP,
+      bc->UsePrivateBrowsing(), true, getter_AddRefs(newPostData));
+
+  // Since aStatus will be NS_OK for 4xx and 5xx error codes we
+  // have to check each request which was upgraded by https-first.
+  // If an error (including 4xx and 5xx) occured, then let's check if
+  // we can downgrade the scheme to HTTP again.
+  bool isHTTPSFirstFixup = false;
+  if (!newURI) {
+    newURI = nsHTTPSOnlyUtils::PotentiallyDowngradeHttpsFirstRequest(mChannel,
+                                                                     aStatus);
+    isHTTPSFirstFixup = true;
+  }
+
+  if (!newURI) {
+    return false;
+  }
+
+  // If we got a new URI, then we should initiate a load with that.
+  // Notify the listeners that this load is complete (with a code that
+  // won't trigger an error page), and then start the new one.
+  DisconnectListeners(NS_BINDING_ABORTED, NS_BINDING_ABORTED);
+
+  RefPtr<nsDocShellLoadState> loadState = new nsDocShellLoadState(newURI);
+  nsCOMPtr<nsILoadInfo> loadInfo = mChannel->LoadInfo();
+
+  nsCOMPtr<nsIContentSecurityPolicy> cspToInherit = loadInfo->GetCspToInherit();
+  loadState->SetCsp(cspToInherit);
+
+  nsCOMPtr<nsIPrincipal> triggeringPrincipal = loadInfo->TriggeringPrincipal();
+  loadState->SetTriggeringPrincipal(triggeringPrincipal);
+
+  loadState->SetPostDataStream(newPostData);
+
+  if (isHTTPSFirstFixup) {
+    // We have to exempt the load from HTTPS-First to prevent a
+    // upgrade-downgrade loop.
+    loadState->SetIsExemptFromHTTPSOnlyMode(true);
+  }
+
+  // Ensure to set referrer information in the fallback channel equally to the
+  // not-upgraded original referrer info.
+  //
+  // A simply copy of the referrer info from the upgraded one leads to problems.
+  // For example:
+  // 1. https://some-site.com redirects to http://other-site.com with referrer
+  // policy
+  //   "no-referrer-when-downgrade".
+  // 2. https-first upgrades the redirection, so redirects to
+  // https://other-site.com,
+  //    according to referrer policy the referrer will be send (https-> https)
+  // 3. Assume other-site.com is not supporting https, https-first performs
+  // fall-
+  //    back.
+  // If the referrer info from the upgraded channel gets copied into the
+  // http fallback channel, the referrer info would contain the referrer
+  // (https://some-site.com). That would violate the policy
+  // "no-referrer-when-downgrade". A recreation of the original referrer info
+  // would ensure us that the referrer is set according to the referrer policy.
+  nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(mChannel);
+  if (httpChannel) {
+    nsCOMPtr<nsIReferrerInfo> referrerInfo = httpChannel->GetReferrerInfo();
+    if (referrerInfo) {
+      ReferrerPolicy referrerPolicy = referrerInfo->ReferrerPolicy();
+      nsCOMPtr<nsIURI> originalReferrer = referrerInfo->GetOriginalReferrer();
+      if (originalReferrer) {
+        // Create new ReferrerInfo with the original referrer and the referrer
+        // policy.
+        nsCOMPtr<nsIReferrerInfo> newReferrerInfo =
+            new ReferrerInfo(originalReferrer, referrerPolicy);
+        loadState->SetReferrerInfo(newReferrerInfo);
+      }
+    }
+  }
+
+  bc->LoadURI(loadState, false);
+  return true;
+}
+
+NS_IMETHODIMP
+DocumentLoadListener::OnStartRequest(nsIRequest* aRequest) {
+  LOG(("DocumentLoadListener OnStartRequest [this=%p]", this));
+
+  nsCOMPtr<nsIMultiPartChannel> multiPartChannel = do_QueryInterface(aRequest);
+  if (multiPartChannel) {
+    multiPartChannel->GetBaseChannel(getter_AddRefs(mChannel));
+  } else {
+    mChannel = do_QueryInterface(aRequest);
+  }
+  MOZ_DIAGNOSTIC_ASSERT(mChannel);
+
+  if (mHaveVisibleRedirect && GetDocumentBrowsingContext() &&
+      mLoadingSessionHistoryInfo) {
+    mLoadingSessionHistoryInfo =
+        GetDocumentBrowsingContext()->ReplaceLoadingSessionHistoryEntryForLoad(
+            mLoadingSessionHistoryInfo.get(), mChannel);
+  }
+
+  RefPtr<nsHttpChannel> httpChannel = do_QueryObject(mChannel);
+
+  // Enforce CSP frame-ancestors and x-frame-options checks which
+  // might cancel the channel.
+  nsContentSecurityUtils::PerformCSPFrameAncestorAndXFOCheck(mChannel);
+
+  // HTTPS-Only Mode tries to upgrade connections to https. Once loading
+  // is in progress we set that flag so that timeout counter measures
+  // do not kick in.
+  if (httpChannel) {
+    nsCOMPtr<nsILoadInfo> loadInfo = httpChannel->LoadInfo();
+    bool isPrivateWin = loadInfo->GetOriginAttributes().mPrivateBrowsingId > 0;
+    if (nsHTTPSOnlyUtils::IsHttpsOnlyModeEnabled(isPrivateWin)) {
+      uint32_t httpsOnlyStatus = loadInfo->GetHttpsOnlyStatus();
+      httpsOnlyStatus |= nsILoadInfo::HTTPS_ONLY_TOP_LEVEL_LOAD_IN_PROGRESS;
+      loadInfo->SetHttpsOnlyStatus(httpsOnlyStatus);
+    }
+
+    if (mLoadingSessionHistoryInfo &&
+        nsDocShell::ShouldDiscardLayoutState(httpChannel)) {
+      mLoadingSessionHistoryInfo->mInfo.SetSaveLayoutStateFlag(false);
+    }
+  }
+
+  auto* loadingContext = GetLoadingBrowsingContext();
+  if (!loadingContext || loadingContext->IsDiscarded()) {
+    Cancel(NS_ERROR_UNEXPECTED, "No valid LoadingBrowsingContext."_ns);
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (AppShutdown::IsInOrBeyond(ShutdownPhase::AppShutdownConfirmed)) {
+    Cancel(NS_ERROR_ILLEGAL_DURING_SHUTDOWN,
+           "Aborting OnStartRequest after shutdown started."_ns);
+    return NS_OK;
+  }
+
+  // Block top-level data URI navigations if triggered by the web. Logging is
+  // performed in AllowTopLevelNavigationToDataURI.
+  if (!nsContentSecurityManager::AllowTopLevelNavigationToDataURI(mChannel)) {
+    mChannel->Cancel(NS_ERROR_DOM_BAD_URI);
+    if (loadingContext) {
+      RefPtr<MaybeCloseWindowHelper> maybeCloseWindowHelper =
+          new MaybeCloseWindowHelper(loadingContext);
+      // If a new window was opened specifically for this request, close it
+      // after blocking the navigation.
+      maybeCloseWindowHelper->SetShouldCloseWindow(
+          IsFirstLoadInWindow(mChannel));
+      Unused << maybeCloseWindowHelper->MaybeCloseWindow();
+    }
+    DisconnectListeners(NS_ERROR_DOM_BAD_URI, NS_ERROR_DOM_BAD_URI);
+    return NS_OK;
+  }
+
+  // Generally we want to switch to a real channel even if the request failed,
+  // since the listener might want to access protocol-specific data (like http
+  // response headers) in its error handling.
+  // An exception to this is when nsExtProtocolChannel handled the request and
+  // returned NS_ERROR_NO_CONTENT, since creating a real one in the content
+  // process will attempt to handle the URI a second time.
+  nsresult status = NS_OK;
+  aRequest->GetStatus(&status);
+  if (status == NS_ERROR_NO_CONTENT) {
+    DisconnectListeners(status, status);
+    return NS_OK;
+  }
+
+  // PerformCSPFrameAncestorAndXFOCheck may cancel a moz-extension request that
+  // needs to be handled here. Without this, the resource would be loaded and
+  // not blocked when the real channel is created in the content process.
+  if (status == NS_ERROR_CSP_FRAME_ANCESTOR_VIOLATION && !httpChannel) {
+    DisconnectListeners(status, status);
+    return NS_OK;
+  }
+
+  // If this was a failed load and we want to try fixing the uri, then
+  // this will initiate a new load (and disconnect this one), and we don't
+  // need to do anything else.
+  if (MaybeHandleLoadErrorWithURIFixup(status)) {
+    return NS_OK;
+  }
+
+  mStreamListenerFunctions.AppendElement(StreamListenerFunction{
+      VariantIndex<0>{}, OnStartRequestParams{aRequest}});
+
+  if (mOpenPromiseResolved || mInitiatedRedirectToRealChannel) {
+    // I we have already resolved the promise, there's no point to continue
+    // attempting a process switch or redirecting to the real channel.
+    // We can also have multiple calls to OnStartRequest when dealing with
+    // multi-part content, but only want to redirect once.
+    return NS_OK;
+  }
+
+  mChannel->Suspend();
+
+  mInitiatedRedirectToRealChannel = true;
+
+  MaybeReportBlockedByURLClassifier(status);
+
+  // Determine if a new process needs to be spawned. If it does, this will
+  // trigger a cross process switch, and we should hold off on redirecting to
+  // the real channel.
+  // If the channel has failed, and the docshell isn't going to display an
+  // error page for that failure, then don't allow process switching, since
+  // we just want to keep our existing document.
+  bool willBeRemote = false;
+  if (!DocShellWillDisplayContent(status) ||
+      !MaybeTriggerProcessSwitch(&willBeRemote)) {
+    // We're not going to be doing a process switch, so redirect to the real
+    // channel within our current process.
+    nsTArray<StreamFilterRequest> streamFilterRequests =
+        std::move(mStreamFilterRequests);
+    if (!mSupportsRedirectToRealChannel) {
+      RefPtr<BrowserParent> browserParent = loadingContext->GetBrowserParent();
+      if (browserParent->Manager() != mContentParent) {
+        LOG(
+            ("DocumentLoadListener::RedirectToRealChannel failed because "
+             "browsingContext no longer owned by creator"));
+        Cancel(NS_BINDING_ABORTED,
+               "DocumentLoadListener::RedirectToRealChannel failed because "
+               "browsingContext no longer owned by creator"_ns);
+        return NS_OK;
+      }
+      MOZ_DIAGNOSTIC_ASSERT(
+          browserParent->GetBrowsingContext() == loadingContext,
+          "make sure the load is going to the right place");
+
+      // If the existing process is right for this load, but the bridge doesn't
+      // support redirects, then we need to do it manually, by faking a process
+      // switch.
+      DisconnectListeners(NS_BINDING_ABORTED, NS_BINDING_ABORTED,
+                          /* aContinueNavigating */ true);
+
+      // Notify the docshell that it should load using the newly connected
+      // channel
+      browserParent->ResumeLoad(mLoadIdentifier);
+
+      // Use the current process ID to run the 'process switch' path and connect
+      // the channel into the current process.
+      TriggerRedirectToRealChannel(Some(mContentParent),
+                                   std::move(streamFilterRequests));
+    } else {
+      TriggerRedirectToRealChannel(Nothing(), std::move(streamFilterRequests));
+    }
+
+    // If we're not switching, then check if we're currently remote.
+    if (mContentParent) {
+      willBeRemote = true;
+    }
+  }
+
+  if (httpChannel) {
+    uint32_t responseStatus = 0;
+    Unused << httpChannel->GetResponseStatus(&responseStatus);
+    mEarlyHintsService.FinalResponse(responseStatus);
+  } else {
+    mEarlyHintsService.Cancel(
+        "DocumentLoadListener::OnStartRequest: no httpChannel"_ns);
+  }
+
+  // If we're going to be delivering this channel to a remote content
+  // process, then we want to install any required content conversions
+  // in the content process.
+  // The caller of this OnStartRequest will install a conversion
+  // helper after we return if we haven't disabled conversion. Normally
+  // HttpChannelParent::OnStartRequest would disable conversion, but we're
+  // defering calling that until later. Manually disable it now to prevent the
+  // converter from being installed (since we want the child to do it), and
+  // also save the value so that when we do call
+  // HttpChannelParent::OnStartRequest, we can have the value as it originally
+  // was.
+  if (httpChannel) {
+    Unused << httpChannel->GetApplyConversion(&mOldApplyConversion);
+    if (willBeRemote) {
+      httpChannel->SetApplyConversion(false);
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+DocumentLoadListener::OnStopRequest(nsIRequest* aRequest,
+                                    nsresult aStatusCode) {
+  LOG(("DocumentLoadListener OnStopRequest [this=%p]", this));
+  mStreamListenerFunctions.AppendElement(StreamListenerFunction{
+      VariantIndex<2>{}, OnStopRequestParams{aRequest, aStatusCode}});
+
+  // If we're not a multi-part channel, then we're finished and we don't
+  // expect any further events. If we are, then this might be called again,
+  // so wait for OnAfterLastPart instead.
+  nsCOMPtr<nsIMultiPartChannel> multiPartChannel = do_QueryInterface(aRequest);
+  if (!multiPartChannel) {
+    mIsFinished = true;
+  }
+
+  mStreamFilterRequests.Clear();
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+DocumentLoadListener::OnDataAvailable(nsIRequest* aRequest,
+                                      nsIInputStream* aInputStream,
+                                      uint64_t aOffset, uint32_t aCount) {
+  LOG(("DocumentLoadListener OnDataAvailable [this=%p]", this));
+  // This isn't supposed to happen, since we suspended the channel, but
+  // sometimes Suspend just doesn't work. This can happen when we're routing
+  // through nsUnknownDecoder to sniff the content type, and it doesn't handle
+  // being suspended. Let's just store the data and manually forward it to our
+  // redirected channel when it's ready.
+  nsCString data;
+  nsresult rv = NS_ReadInputStreamToString(aInputStream, data, aCount);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  mStreamListenerFunctions.AppendElement(StreamListenerFunction{
+      VariantIndex<1>{},
+      OnDataAvailableParams{aRequest, data, aOffset, aCount}});
+
+  return NS_OK;
+}
+
+//-----------------------------------------------------------------------------
+// DoucmentLoadListener::nsIMultiPartChannelListener
+//-----------------------------------------------------------------------------
+
+NS_IMETHODIMP
+DocumentLoadListener::OnAfterLastPart(nsresult aStatus) {
+  LOG(("DocumentLoadListener OnAfterLastPart [this=%p]", this));
+  if (!mInitiatedRedirectToRealChannel) {
+    // if we get here, and we haven't initiated a redirect to a real
+    // channel, then it means we never got OnStartRequest (maybe a problem?)
+    // and we retargeted everything.
+    LOG(("DocumentLoadListener Disconnecting child"));
+    DisconnectListeners(NS_BINDING_RETARGETED, NS_OK);
+    return NS_OK;
+  }
+  mStreamListenerFunctions.AppendElement(StreamListenerFunction{
+      VariantIndex<3>{}, OnAfterLastPartParams{aStatus}});
+  mIsFinished = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+DocumentLoadListener::GetInterface(const nsIID& aIID, void** result) {
+  RefPtr<CanonicalBrowsingContext> browsingContext =
+      GetLoadingBrowsingContext();
+  if (aIID.Equals(NS_GET_IID(nsILoadContext)) && browsingContext) {
+    browsingContext.forget(result);
+    return NS_OK;
+  }
+
+  return QueryInterface(aIID, result);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// nsIParentChannel
+////////////////////////////////////////////////////////////////////////////////
+
+NS_IMETHODIMP
+DocumentLoadListener::SetParentListener(
+    mozilla::net::ParentChannelListener* listener) {
+  // We don't need this (do we?)
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+DocumentLoadListener::SetClassifierMatchedInfo(const nsACString& aList,
+                                               const nsACString& aProvider,
+                                               const nsACString& aFullHash) {
+  ClassifierMatchedInfoParams params;
+  params.mList = aList;
+  params.mProvider = aProvider;
+  params.mFullHash = aFullHash;
+
+  mIParentChannelFunctions.AppendElement(
+      IParentChannelFunction{VariantIndex<0>{}, std::move(params)});
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+DocumentLoadListener::SetClassifierMatchedTrackingInfo(
+    const nsACString& aLists, const nsACString& aFullHash) {
+  ClassifierMatchedTrackingInfoParams params;
+  params.mLists = aLists;
+  params.mFullHashes = aFullHash;
+
+  mIParentChannelFunctions.AppendElement(
+      IParentChannelFunction{VariantIndex<1>{}, std::move(params)});
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+DocumentLoadListener::NotifyClassificationFlags(uint32_t aClassificationFlags,
+                                                bool aIsThirdParty) {
+  mIParentChannelFunctions.AppendElement(IParentChannelFunction{
+      VariantIndex<2>{},
+      ClassificationFlagsParams{aClassificationFlags, aIsThirdParty}});
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+DocumentLoadListener::Delete() {
+  MOZ_ASSERT_UNREACHABLE("This method is unused");
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+DocumentLoadListener::GetRemoteType(nsACString& aRemoteType) {
+  // FIXME: The remote type here should be pulled from the remote process used
+  // to create this DLL, not from the current `browsingContext`.
+  RefPtr<CanonicalBrowsingContext> browsingContext =
+      GetDocumentBrowsingContext();
+  if (!browsingContext) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  ErrorResult error;
+  browsingContext->GetCurrentRemoteType(aRemoteType, error);
+  if (error.Failed()) {
+    aRemoteType = NOT_REMOTE_TYPE;
+  }
+  return NS_OK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// nsIChannelEventSink
+////////////////////////////////////////////////////////////////////////////////
+
+NS_IMETHODIMP
+DocumentLoadListener::AsyncOnChannelRedirect(
+    nsIChannel* aOldChannel, nsIChannel* aNewChannel, uint32_t aFlags,
+    nsIAsyncVerifyRedirectCallback* aCallback) {
+  LOG(("DocumentLoadListener::AsyncOnChannelRedirect [this=%p flags=%" PRIu32
+       "]",
+       this, aFlags));
+  // We generally don't want to notify the content process about redirects,
+  // so just update our channel and tell the callback that we're good to go.
+  mChannel = aNewChannel;
+
+  // We need the original URI of the current channel to use to open the real
+  // channel in the content process. Unfortunately we overwrite the original
+  // uri of the new channel with the original pre-redirect URI, so grab
+  // a copy of it now and save it on the loadInfo corresponding to the
+  // new channel.
+  nsCOMPtr<nsILoadInfo> loadInfoFromChannel = mChannel->LoadInfo();
+  MOZ_ASSERT(loadInfoFromChannel);
+  nsCOMPtr<nsIURI> uri;
+  mChannel->GetOriginalURI(getter_AddRefs(uri));
+  loadInfoFromChannel->SetChannelCreationOriginalURI(uri);
+
+  // Since we're redirecting away from aOldChannel, we should check if it
+  // had a COOP mismatch, since we want the final result for this to
+  // include the state of all channels we redirected through.
+  nsCOMPtr<nsIHttpChannelInternal> httpChannel = do_QueryInterface(aOldChannel);
+  if (httpChannel) {
+    bool isCOOPMismatch = false;
+    Unused << NS_WARN_IF(NS_FAILED(
+        httpChannel->HasCrossOriginOpenerPolicyMismatch(&isCOOPMismatch)));
+    mHasCrossOriginOpenerPolicyMismatch |= isCOOPMismatch;
+  }
+
+  // If HTTPS-Only mode is enabled, we need to check whether the exception-flag
+  // needs to be removed or set, by asking the PermissionManager.
+  nsHTTPSOnlyUtils::TestSitePermissionAndPotentiallyAddExemption(mChannel);
+
+  // We don't need to confirm internal redirects or record any
+  // history for them, so just immediately verify and return.
+  if (aFlags & nsIChannelEventSink::REDIRECT_INTERNAL) {
+    LOG(
+        ("DocumentLoadListener AsyncOnChannelRedirect [this=%p] "
+         "flags=REDIRECT_INTERNAL",
+         this));
+    aCallback->OnRedirectVerifyCallback(NS_OK);
+    return NS_OK;
+  }
+
+  // Cancel cross origin redirects as described by whatwg:
+  // > Note: [The early hint reponse] is discarded if it is succeeded by a
+  // > cross-origin redirect.
+  // https://html.spec.whatwg.org/multipage/semantics.html#early-hints
+  nsCOMPtr<nsIURI> oldURI;
+  aOldChannel->GetURI(getter_AddRefs(oldURI));
+  nsIScriptSecurityManager* ssm = nsContentUtils::GetSecurityManager();
+  nsresult rv = ssm->CheckSameOriginURI(oldURI, uri, false, false);
+  if (NS_FAILED(rv)) {
+    mEarlyHintsService.Cancel(
+        "DocumentLoadListener::AsyncOnChannelRedirect: cors redirect"_ns);
+  }
+
+  if (GetDocumentBrowsingContext()) {
+    if (!net::ChannelIsPost(aOldChannel)) {
+      AddURIVisit(aOldChannel, 0);
+      nsDocShell::SaveLastVisit(aNewChannel, oldURI, aFlags);
+    }
+  }
+  mHaveVisibleRedirect |= true;
+
+  LOG(
+      ("DocumentLoadListener AsyncOnChannelRedirect [this=%p] "
+       "mHaveVisibleRedirect=%c",
+       this, mHaveVisibleRedirect ? 'T' : 'F'));
+
+  // Clear out our nsIParentChannel functions, since a normal parent
+  // channel would actually redirect and not have those values on the new one.
+  // We expect the URI classifier to run on the redirected channel with
+  // the new URI and set these again.
+  mIParentChannelFunctions.Clear();
+
+  // If we had a remote type override, ensure it's been cleared after a
+  // redirect, as it can't apply anymore.
+  mRemoteTypeOverride.reset();
+
+#ifdef ANDROID
+  nsCOMPtr<nsIURI> uriBeingLoaded =
+      AntiTrackingUtils::MaybeGetDocumentURIBeingLoaded(mChannel);
+
+  RefPtr<MozPromise<bool, bool, false>> promise;
+  RefPtr<CanonicalBrowsingContext> bc =
+      mParentChannelListener->GetBrowsingContext();
+  nsCOMPtr<nsIWidget> widget =
+      bc ? bc->GetParentProcessWidgetContaining() : nullptr;
+  RefPtr<nsWindow> window = nsWindow::From(widget);
+
+  if (window) {
+    promise = window->OnLoadRequest(uriBeingLoaded,
+                                    nsIBrowserDOMWindow::OPEN_CURRENTWINDOW,
+                                    nsIWebNavigation::LOAD_FLAGS_IS_REDIRECT,
+                                    nullptr, false, bc->IsTopContent());
+  }
+
+  if (promise) {
+    RefPtr<nsIAsyncVerifyRedirectCallback> cb = aCallback;
+    promise->Then(
+        GetCurrentSerialEventTarget(), __func__,
+        [=](const MozPromise<bool, bool, false>::ResolveOrRejectValue& aValue) {
+          if (aValue.IsResolve()) {
+            bool handled = aValue.ResolveValue();
+            if (handled) {
+              cb->OnRedirectVerifyCallback(NS_ERROR_ABORT);
+            } else {
+              cb->OnRedirectVerifyCallback(NS_OK);
+            }
+          }
+        });
+  } else
+#endif /* ANDROID */
+  {
+    aCallback->OnRedirectVerifyCallback(NS_OK);
+  }
+  return NS_OK;
+}
+
+nsIURI* DocumentLoadListener::GetChannelCreationURI() const {
+  nsCOMPtr<nsILoadInfo> channelLoadInfo = mChannel->LoadInfo();
+
+  nsCOMPtr<nsIURI> uri;
+  channelLoadInfo->GetChannelCreationOriginalURI(getter_AddRefs(uri));
+  if (uri) {
+    // See channelCreationOriginalURI for more info. We use this instead of the
+    // originalURI of the channel to help us avoid the situation when we use
+    // the URI of a redirect that has failed to happen.
+    return uri;
+  }
+
+  // Otherwise, get the original URI from the channel.
+  mChannel->GetOriginalURI(getter_AddRefs(uri));
+  return uri;
+}
+
+// This method returns the cached result of running the Cross-Origin-Opener
+// policy compare algorithm by calling ComputeCrossOriginOpenerPolicyMismatch
+bool DocumentLoadListener::HasCrossOriginOpenerPolicyMismatch() const {
+  // If we found a COOP mismatch on an earlier channel and then
+  // redirected away from that, we should use that result.
+  if (mHasCrossOriginOpenerPolicyMismatch) {
+    return true;
+  }
+
+  nsCOMPtr<nsIHttpChannelInternal> httpChannel = do_QueryInterface(mChannel);
+  if (!httpChannel) {
+    // Not an nsIHttpChannelInternal assume it's okay to switch.
+    return false;
+  }
+
+  bool isCOOPMismatch = false;
+  Unused << NS_WARN_IF(NS_FAILED(
+      httpChannel->HasCrossOriginOpenerPolicyMismatch(&isCOOPMismatch)));
+  return isCOOPMismatch;
+}
+
+auto DocumentLoadListener::AttachStreamFilter()
+    -> RefPtr<ChildEndpointPromise> {
+  LOG(("DocumentLoadListener AttachStreamFilter [this=%p]", this));
+
+  StreamFilterRequest* request = mStreamFilterRequests.AppendElement();
+  request->mPromise = new ChildEndpointPromise::Private(__func__);
+  return request->mPromise;
+}
+
+NS_IMETHODIMP DocumentLoadListener::OnProgress(nsIRequest* aRequest,
+                                               int64_t aProgress,
+                                               int64_t aProgressMax) {
+  return NS_OK;
+}
+
+NS_IMETHODIMP DocumentLoadListener::OnStatus(nsIRequest* aRequest,
+                                             nsresult aStatus,
+                                             const char16_t* aStatusArg) {
+  nsCOMPtr<nsIChannel> channel = mChannel;
+
+  RefPtr<BrowsingContextWebProgress> webProgress =
+      GetLoadingBrowsingContext()->GetWebProgress();
+  const nsString message(aStatusArg);
+
+  if (webProgress) {
+    NS_DispatchToMainThread(
+        NS_NewRunnableFunction("DocumentLoadListener::OnStatus", [=]() {
+          webProgress->OnStatusChange(webProgress, channel, aStatus,
+                                      message.get());
+        }));
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP DocumentLoadListener::EarlyHint(const nsACString& aLinkHeader,
+                                              const nsACString& aReferrerPolicy,
+                                              const nsACString& aCSPHeader) {
+  LOG(("DocumentLoadListener::EarlyHint.\n"));
+  mEarlyHintsService.EarlyHint(aLinkHeader, GetChannelCreationURI(), mChannel,
+                               aReferrerPolicy, aCSPHeader);
+  return NS_OK;
+}
+
+}  // namespace net
+}  // namespace mozilla
+
+#undef LOG
diff --git a/netwerk/ipc/DocumentLoadListener.h b/netwerk/ipc/DocumentLoadListener.h
new file mode 100644
index 0000000000..c2c443fef6
--- /dev/null
+++ b/netwerk/ipc/DocumentLoadListener.h
@@ -0,0 +1,630 @@
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_DocumentLoadListener_h
+#define mozilla_net_DocumentLoadListener_h
+
+#include "mozilla/MozPromise.h"
+#include "mozilla/Variant.h"
+#include "mozilla/WeakPtr.h"
+#include "mozilla/ipc/Endpoint.h"
+#include "mozilla/dom/SessionHistoryEntry.h"
+#include "EarlyHintsService.h"
+#include "mozilla/net/NeckoCommon.h"
+#include "mozilla/net/NeckoParent.h"
+#include "mozilla/net/PDocumentChannelParent.h"
+#include "mozilla/net/ParentChannelListener.h"
+#include "nsDOMNavigationTiming.h"
+#include "nsIBrowser.h"
+#include "nsIChannelEventSink.h"
+#include "nsIEarlyHintObserver.h"
+#include "nsIInterfaceRequestor.h"
+#include "nsIMultiPartChannel.h"
+#include "nsIParentChannel.h"
+#include "nsIParentRedirectingChannel.h"
+#include "nsIProgressEventSink.h"
+#include "nsIRedirectResultListener.h"
+
+#define DOCUMENT_LOAD_LISTENER_IID                   \
+  {                                                  \
+    0x3b393c56, 0x9e01, 0x11e9, {                    \
+      0xa2, 0xa3, 0x2a, 0x2a, 0xe2, 0xdb, 0xcc, 0xe4 \
+    }                                                \
+  }
+
+namespace mozilla {
+namespace dom {
+class CanonicalBrowsingContext;
+struct NavigationIsolationOptions;
+}  // namespace dom
+namespace net {
+using ChildEndpointPromise =
+    MozPromise<mozilla::ipc::Endpoint<extensions::PStreamFilterChild>, bool,
+               true>;
+
+// If we've been asked to attach a stream filter to our channel,
+// then we return this promise and defer until we know the final
+// content process. At that point we setup Endpoints between
+// mStramFilterProcessId and the new content process, and send
+// the parent Endpoint to the new process.
+// Once we have confirmation of that being bound in the content
+// process, we resolve the promise the child Endpoint.
+struct StreamFilterRequest {
+  StreamFilterRequest() = default;
+  StreamFilterRequest(StreamFilterRequest&&) = default;
+  ~StreamFilterRequest() {
+    if (mPromise) {
+      mPromise->Reject(false, __func__);
+    }
+  }
+  RefPtr<ChildEndpointPromise::Private> mPromise;
+  mozilla::ipc::Endpoint<extensions::PStreamFilterChild> mChildEndpoint;
+};
+}  // namespace net
+}  // namespace mozilla
+MOZ_DECLARE_RELOCATE_USING_MOVE_CONSTRUCTOR(mozilla::net::StreamFilterRequest)
+
+namespace mozilla {
+namespace net {
+
+class LoadInfo;
+
+/**
+ * DocumentLoadListener represents a connecting document load for a
+ * CanonicalBrowsingContext (in the parent process).
+ *
+ * It creates a network channel for the document load and then waits for it to
+ * receive a response (after all redirects are resolved). It then decides where
+ * to handle that load (could be in a different process from the initiator),
+ * and then sets up a real network nsIChannel to deliver the data to the final
+ * destination docshell, maybe through an nsIParentChannel/nsIChildChannel IPDL
+ * layer.
+ *
+ * In the case where this was initiated from an nsDocShell, we also create an
+ * nsIChannel to act as a placeholder within the docshell while this process
+ * completes, and then notify the docshell of a 'redirect' when we replace this
+ * channel with the real one.
+ */
+
+// TODO: We currently don't implement nsIProgressEventSink and forward those
+// to the child. Should we? We get the interface requested.
+class DocumentLoadListener : public nsIInterfaceRequestor,
+                             public nsIAsyncVerifyRedirectReadyCallback,
+                             public nsIParentChannel,
+                             public nsIChannelEventSink,
+                             public HttpChannelSecurityWarningReporter,
+                             public nsIMultiPartChannelListener,
+                             public nsIProgressEventSink,
+                             public nsIEarlyHintObserver {
+ public:
+  // See the comment on GetLoadingBrowsingContext for explanation of
+  // aLoadingBrowsingContext.
+  DocumentLoadListener(dom::CanonicalBrowsingContext* aLoadingBrowsingContext,
+                       bool aIsDocumentLoad);
+
+  struct OpenPromiseSucceededType {
+    nsTArray<mozilla::ipc::Endpoint<extensions::PStreamFilterParent>>
+        mStreamFilterEndpoints;
+    uint32_t mRedirectFlags;
+    uint32_t mLoadFlags;
+    uint32_t mEarlyHintLinkType;
+    RefPtr<PDocumentChannelParent::RedirectToRealChannelPromise::Private>
+        mPromise;
+  };
+  struct OpenPromiseFailedType {
+    nsresult mStatus;
+    nsresult mLoadGroupStatus;
+    // This is set to true if the navigation in the content process should not
+    // be cancelled, as the load is logically continuing within the current
+    // browsing session, just within a different process or browsing context.
+    bool mContinueNavigating = false;
+  };
+
+  using OpenPromise =
+      MozPromise<OpenPromiseSucceededType, OpenPromiseFailedType, true>;
+
+  // Interface which may be provided when performing an <object> or <embed> load
+  // with `DocumentLoadListener`, to allow upgrading the Object load to a proper
+  // Document load.
+  struct ObjectUpgradeHandler : public SupportsWeakPtr {
+    using ObjectUpgradePromise =
+        MozPromise<RefPtr<dom::CanonicalBrowsingContext>, nsresult,
+                   true /* isExclusive */>;
+
+    // Upgrade an object load to be a potentially remote document.
+    //
+    // The returned promise will resolve with the BrowsingContext which has been
+    // created in the <object> or <embed> element to finish the load with.
+    virtual RefPtr<ObjectUpgradePromise> UpgradeObjectLoad() = 0;
+  };
+
+ private:
+  // Creates the channel, and then calls AsyncOpen on it.
+  // The DocumentLoadListener will require additional process from the consumer
+  // in order to complete the redirect to the end channel. This is done by
+  // returning a RedirectToRealChannelPromise and then waiting for it to be
+  // resolved or rejected accordingly.
+  // Once that promise is resolved; the consumer no longer needs to hold a
+  // reference to the DocumentLoadListener nor will the consumer required to be
+  // used again.
+  RefPtr<OpenPromise> Open(nsDocShellLoadState* aLoadState, LoadInfo* aLoadInfo,
+                           nsLoadFlags aLoadFlags, uint32_t aCacheKey,
+                           const Maybe<uint64_t>& aChannelId,
+                           const TimeStamp& aAsyncOpenTime,
+                           nsDOMNavigationTiming* aTiming,
+                           Maybe<dom::ClientInfo>&& aInfo, bool aUrgentStart,
+                           dom::ContentParent* aContentParent, nsresult* aRv);
+
+ public:
+  RefPtr<OpenPromise> OpenDocument(
+      nsDocShellLoadState* aLoadState, uint32_t aCacheKey,
+      const Maybe<uint64_t>& aChannelId, const TimeStamp& aAsyncOpenTime,
+      nsDOMNavigationTiming* aTiming, Maybe<dom::ClientInfo>&& aInfo,
+      Maybe<bool> aUriModified, Maybe<bool> aIsXFOError,
+      dom::ContentParent* aContentParent, nsresult* aRv);
+
+  RefPtr<OpenPromise> OpenObject(
+      nsDocShellLoadState* aLoadState, uint32_t aCacheKey,
+      const Maybe<uint64_t>& aChannelId, const TimeStamp& aAsyncOpenTime,
+      nsDOMNavigationTiming* aTiming, Maybe<dom::ClientInfo>&& aInfo,
+      uint64_t aInnerWindowId, nsLoadFlags aLoadFlags,
+      nsContentPolicyType aContentPolicyType, bool aUrgentStart,
+      dom::ContentParent* aContentParent,
+      ObjectUpgradeHandler* aObjectUpgradeHandler, nsresult* aRv);
+
+  // Creates a DocumentLoadListener entirely in the parent process and opens it,
+  // and never needs a DocumentChannel to connect to an existing docshell.
+  // Once we get a response it takes the 'process switch' path to find the right
+  // process and docshell, and delivers the response there directly.
+  static bool LoadInParent(dom::CanonicalBrowsingContext* aBrowsingContext,
+                           nsDocShellLoadState* aLoadState,
+                           bool aSetNavigating);
+
+  // Creates a DocumentLoadListener directly in the parent process and opens it,
+  // without needing an existing DocumentChannel.
+  // If successful it registers a unique identifier (return in aOutIdent) to
+  // keep it alive until a future DocumentChannel can attach to it, or we fail
+  // and clean up.
+  static bool SpeculativeLoadInParent(
+      dom::CanonicalBrowsingContext* aBrowsingContext,
+      nsDocShellLoadState* aLoadState);
+
+  // Ensures that a load identifier allocated by OpenFromParent has
+  // been deregistered if it hasn't already been claimed.
+  // This also cancels the load.
+  static void CleanupParentLoadAttempt(uint64_t aLoadIdent);
+
+  // Looks up aLoadIdent to find the associated, cleans up the registration
+  static RefPtr<OpenPromise> ClaimParentLoad(DocumentLoadListener** aListener,
+                                             uint64_t aLoadIdent,
+                                             Maybe<uint64_t> aChannelId);
+
+  // Called by the DocumentChannelParent if actor got destroyed or the parent
+  // channel got deleted.
+  void Abort();
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIREQUESTOBSERVER
+  NS_DECL_NSISTREAMLISTENER
+  NS_DECL_NSIPARENTCHANNEL
+  NS_DECL_NSIINTERFACEREQUESTOR
+  NS_DECL_NSIASYNCVERIFYREDIRECTREADYCALLBACK
+  NS_DECL_NSICHANNELEVENTSINK
+  NS_DECL_NSIMULTIPARTCHANNELLISTENER
+  NS_DECL_NSIPROGRESSEVENTSINK
+  NS_DECL_NSIEARLYHINTOBSERVER
+
+  // We suspend the underlying channel when replacing ourselves with
+  // the real listener channel.
+  // This helper resumes the underlying channel again, and manually
+  // forwards any nsIStreamListener messages that arrived while we
+  // were suspended (which might have failed).
+  // Returns true if the channel was finished before we could resume it.
+  bool ResumeSuspendedChannel(nsIStreamListener* aListener);
+
+  NS_DECLARE_STATIC_IID_ACCESSOR(DOCUMENT_LOAD_LISTENER_IID)
+
+  // Called by the DocumentChannel if cancelled.
+  void Cancel(const nsresult& aStatusCode, const nsACString& aReason);
+
+  nsIChannel* GetChannel() const { return mChannel; }
+
+  uint32_t GetRedirectChannelId() const { return mRedirectChannelId; }
+
+  nsresult ReportSecurityMessage(const nsAString& aMessageTag,
+                                 const nsAString& aMessageCategory) override {
+    ReportSecurityMessageParams params;
+    params.mMessageTag = aMessageTag;
+    params.mMessageCategory = aMessageCategory;
+    mSecurityWarningFunctions.AppendElement(
+        SecurityWarningFunction{VariantIndex<0>{}, std::move(params)});
+    return NS_OK;
+  }
+
+  nsresult LogBlockedCORSRequest(const nsAString& aMessage,
+                                 const nsACString& aCategory,
+                                 bool aIsWarning) override {
+    LogBlockedCORSRequestParams params;
+    params.mMessage = aMessage;
+    params.mCategory = aCategory;
+    params.mIsWarning = aIsWarning;
+    mSecurityWarningFunctions.AppendElement(
+        SecurityWarningFunction{VariantIndex<1>{}, std::move(params)});
+    return NS_OK;
+  }
+
+  nsresult LogMimeTypeMismatch(const nsACString& aMessageName, bool aWarning,
+                               const nsAString& aURL,
+                               const nsAString& aContentType) override {
+    LogMimeTypeMismatchParams params;
+    params.mMessageName = aMessageName;
+    params.mWarning = aWarning;
+    params.mURL = aURL;
+    params.mContentType = aContentType;
+    mSecurityWarningFunctions.AppendElement(
+        SecurityWarningFunction{VariantIndex<2>{}, std::move(params)});
+    return NS_OK;
+  }
+
+  // The content process corresponding to this DocumentLoadListener, or nullptr
+  // if connected to the parent process.
+  dom::ContentParent* GetContentParent() const { return mContentParent; }
+
+  // The process id of the content process that we are being called from
+  // or 0 initiated from a parent process load.
+  base::ProcessId OtherPid() const;
+
+  [[nodiscard]] RefPtr<ChildEndpointPromise> AttachStreamFilter();
+
+  // EarlyHints aren't supported on ParentProcessDocumentChannels yet, allow
+  // EarlyHints to be cancelled from there (Bug 1819886)
+  void CancelEarlyHintPreloads();
+
+  // Gets the EarlyHint preloads for this document to pass them to the
+  // ContentProcess. Registers them in the EarlyHintRegister
+  void RegisterEarlyHintLinksAndGetConnectArgs(
+      dom::ContentParentId aCpId, nsTArray<EarlyHintConnectArgs>& aOutLinks);
+
+  // Serializes all data needed to setup the new replacement channel
+  // in the content process into the RedirectToRealChannelArgs struct.
+  void SerializeRedirectData(RedirectToRealChannelArgs& aArgs,
+                             bool aIsCrossProcess, uint32_t aRedirectFlags,
+                             uint32_t aLoadFlags, dom::ContentParent* aParent,
+                             nsTArray<EarlyHintConnectArgs>&& aEarlyHints,
+                             uint32_t aEarlyHintLinkType) const;
+
+  uint64_t GetLoadIdentifier() const { return mLoadIdentifier; }
+  uint32_t GetLoadType() const { return mLoadStateLoadType; }
+  bool IsDownload() const { return mIsDownload; }
+  bool IsLoadingJSURI() const { return mIsLoadingJSURI; }
+
+  mozilla::dom::LoadingSessionHistoryInfo* GetLoadingSessionHistoryInfo() {
+    return mLoadingSessionHistoryInfo.get();
+  }
+
+  bool IsDocumentLoad() const { return mIsDocumentLoad; }
+
+  // Determine what process switching behavior a browser element should have.
+  enum ProcessBehavior : uint8_t {
+    // Gecko won't automatically change which process this frame, or it's
+    // subframes, are loaded in.
+    PROCESS_BEHAVIOR_DISABLED,
+
+    // If `useRemoteTabs` is enabled, Gecko will change which process this frame
+    // is loaded in automatically, without calling `performProcessSwitch`.
+    // When `useRemoteSubframes` is enabled, subframes will change processes.
+    PROCESS_BEHAVIOR_STANDARD,
+
+    // Gecko won't automatically change which process this frame is loaded, but
+    // when `useRemoteSubframes` is enabled, subframes will change processes.
+    //
+    // NOTE: This configuration is included only for backwards compatibility,
+    // and will be removed, as it can easily lead to invalid behavior.
+    PROCESS_BEHAVIOR_SUBFRAME_ONLY,
+  };
+
+ protected:
+  virtual ~DocumentLoadListener();
+
+ private:
+  RefPtr<OpenPromise> OpenInParent(nsDocShellLoadState* aLoadState,
+                                   bool aSupportsRedirectToRealChannel);
+
+  friend class ParentProcessDocumentOpenInfo;
+
+  // Will reject the promise to notify the DLL consumer that we are done.
+  //
+  // If `aContinueNavigating` is true, the navigation in the content process
+  // will not be aborted, as navigation is logically continuing in the existing
+  // browsing session (e.g. due to a process switch or entering the bfcache).
+  void DisconnectListeners(nsresult aStatus, nsresult aLoadGroupStatus,
+                           bool aContinueNavigating = false);
+
+  // Called when we were created without a document channel, and creation has
+  // failed, and won't ever be attached.
+  void NotifyDocumentChannelFailed();
+
+  // Initiates the switch from DocumentChannel to the real protocol-specific
+  // channel, and ensures that RedirectToRealChannelFinished is called when
+  // this is complete.
+  void TriggerRedirectToRealChannel(
+      const Maybe<dom::ContentParent*>& aDestinationProcess,
+      nsTArray<StreamFilterRequest> aStreamFilterRequests);
+
+  // Called once the content-process side on setting up a replacement
+  // channel is complete. May wait for the new parent channel to
+  // finish, and then calls into FinishReplacementChannelSetup.
+  void RedirectToRealChannelFinished(nsresult aRv);
+
+  // Completes the replacement of the new channel.
+  // This redirects the ParentChannelListener to forward any future
+  // messages to the new channel, manually forwards any being held
+  // by us, and resumes the underlying source channel.
+  void FinishReplacementChannelSetup(nsresult aResult);
+
+  // Called from `OnStartRequest` to make the decision about whether or not to
+  // change process. This method will return `nullptr` if the current target
+  // process is appropriate.
+  // aWillSwitchToRemote is set to true if we initiate a process switch,
+  // and that the new remote type will be something other than NOT_REMOTE
+  bool MaybeTriggerProcessSwitch(bool* aWillSwitchToRemote);
+
+  // Called when the process switch is going to happen, potentially
+  // asynchronously, from `MaybeTriggerProcessSwitch`.
+  //
+  // aContext should be the target context for the navigation. This will either
+  // be the loading BrowsingContext, the newly created BrowsingContext for an
+  // object or embed element load, or a newly created tab for new tab load.
+  //
+  // If `aIsNewTab` is specified, the navigation in the original process will be
+  // aborted immediately, rather than waiting for a process switch to happen and
+  // the previous page to be unloaded or hidden.
+  void TriggerProcessSwitch(dom::CanonicalBrowsingContext* aContext,
+                            const dom::NavigationIsolationOptions& aOptions,
+                            bool aIsNewTab = false);
+
+  // A helper for TriggerRedirectToRealChannel that abstracts over
+  // the same-process and cross-process switch cases and returns
+  // a single promise to wait on.
+  using ParentEndpoint =
+      mozilla::ipc::Endpoint<extensions::PStreamFilterParent>;
+  RefPtr<PDocumentChannelParent::RedirectToRealChannelPromise>
+  RedirectToRealChannel(uint32_t aRedirectFlags, uint32_t aLoadFlags,
+                        const Maybe<dom::ContentParent*>& aDestinationProcess,
+                        nsTArray<ParentEndpoint>&& aStreamFilterEndpoints);
+
+  // A helper for RedirectToRealChannel that handles the case where we started
+  // from a content process and are process switching into the parent process.
+  RefPtr<PDocumentChannelParent::RedirectToRealChannelPromise>
+  RedirectToParentProcess(uint32_t aRedirectFlags, uint32_t aLoadFlags);
+
+  // Return the Browsing Context that is performing the load.
+  // For document loads, the BC is the one that the (sub)doc
+  // will load into. For <object>/<embed>, it's the embedder document's BC.
+  dom::CanonicalBrowsingContext* GetLoadingBrowsingContext() const;
+
+  // Return the Browsing Context that document is being loaded into. For
+  // non-document loads, this will return nullptr.
+  dom::CanonicalBrowsingContext* GetDocumentBrowsingContext() const;
+  dom::CanonicalBrowsingContext* GetTopBrowsingContext() const;
+
+  // Return the Window Context which which contains the element which the load
+  // is being performed in. For toplevel loads, this will return `nullptr`.
+  dom::WindowGlobalParent* GetParentWindowContext() const;
+
+  void AddURIVisit(nsIChannel* aChannel, uint32_t aLoadFlags);
+  bool HasCrossOriginOpenerPolicyMismatch() const;
+  void ApplyPendingFunctions(nsIParentChannel* aChannel) const;
+
+  void Disconnect(bool aContinueNavigating);
+
+  void MaybeReportBlockedByURLClassifier(nsresult aStatus);
+
+  // Returns true if a channel with aStatus will display
+  // some sort of content (could be the actual channel data,
+  // attempt a uri fixup and new load, or an error page).
+  // Returns false if the docshell will ignore the load entirely.
+  bool DocShellWillDisplayContent(nsresult aStatus);
+
+  void FireStateChange(uint32_t aStateFlags, nsresult aStatus);
+
+  // Returns true if this is a failed load, where we have successfully
+  // created a fixed URI to attempt loading instead.
+  // If successful, this calls DisconnectListeners to completely finish
+  // the current load, and calls BrowsingContext::LoadURI to start the new one.
+  bool MaybeHandleLoadErrorWithURIFixup(nsresult aStatus);
+
+  // This defines a variant that describes all the attribute setters (and their
+  // parameters) from nsIParentChannel
+  //
+  // SetClassifierMatchedInfo(const nsACString& aList, const nsACString&
+  // aProvider, const nsACString& aFullHash) = 0;
+  // SetClassifierMatchedTrackingInfo(const nsACString& aLists, const
+  // nsACString& aFullHashes) = 0; NotifyClassificationFlags(uint32_t
+  // aClassificationFlags, bool aIsThirdParty) = 0;
+  struct ClassifierMatchedInfoParams {
+    nsCString mList;
+    nsCString mProvider;
+    nsCString mFullHash;
+  };
+
+  struct ClassifierMatchedTrackingInfoParams {
+    nsCString mLists;
+    nsCString mFullHashes;
+  };
+
+  struct ClassificationFlagsParams {
+    uint32_t mClassificationFlags;
+    bool mIsThirdParty;
+  };
+
+  using IParentChannelFunction =
+      mozilla::Variant<ClassifierMatchedInfoParams,
+                       ClassifierMatchedTrackingInfoParams,
+                       ClassificationFlagsParams>;
+
+  // Store a list of all the attribute setters that have been called on this
+  // channel, so that we can repeat them on the real channel that we redirect
+  // to.
+  nsTArray<IParentChannelFunction> mIParentChannelFunctions;
+
+  // This defines a variant this describes all the functions
+  // from HttpChannelSecurityWarningReporter so that we can forward
+  // them on to the real channel.
+
+  struct ReportSecurityMessageParams {
+    nsString mMessageTag;
+    nsString mMessageCategory;
+  };
+
+  struct LogBlockedCORSRequestParams {
+    nsString mMessage;
+    nsCString mCategory;
+    bool mIsWarning;
+  };
+
+  struct LogMimeTypeMismatchParams {
+    nsCString mMessageName;
+    bool mWarning = false;
+    nsString mURL;
+    nsString mContentType;
+  };
+
+  using SecurityWarningFunction =
+      mozilla::Variant<ReportSecurityMessageParams, LogBlockedCORSRequestParams,
+                       LogMimeTypeMismatchParams>;
+  nsTArray<SecurityWarningFunction> mSecurityWarningFunctions;
+
+  // TODO Backtrack this.
+  // The set of nsIStreamListener functions that got called on this
+  // listener, so that we can replay them onto the replacement channel's
+  // listener. This should generally only be OnStartRequest, since we
+  // Suspend() the channel at that point, but it can fail sometimes
+  // so we have to support holding a list.
+  nsTArray<StreamListenerFunction> mStreamListenerFunctions;
+
+  nsCOMPtr<nsIChannel> mChannel;
+
+  Maybe<uint64_t> mDocumentChannelId;
+
+  // An instance of ParentChannelListener that we use as a listener
+  // between mChannel (and any future redirected mChannels) and us.
+  // This handles service worker interception, and retargetting
+  // OnDataAvailable/OnStopRequest messages onto the listener that
+  // replaces us.
+  RefPtr<ParentChannelListener> mParentChannelListener;
+
+  // Get the channel creation URI for constructing the channel in the content
+  // process. See the function for more details.
+  nsIURI* GetChannelCreationURI() const;
+
+  // The original navigation timing information containing various timestamps
+  // such as when the original load started.
+  // This will be passed back to the new content process should a process
+  // switch occurs.
+  RefPtr<nsDOMNavigationTiming> mTiming;
+
+  net::EarlyHintsService mEarlyHintsService;
+
+  // An optional ObjectUpgradeHandler which can be used to upgrade an <object>
+  // or <embed> element to contain a nsFrameLoader, allowing us to switch them
+  // into a different process.
+  //
+  // A weak pointer is held in order to avoid reference cycles.
+  WeakPtr<ObjectUpgradeHandler> mObjectUpgradeHandler;
+
+  // Used to identify an internal redirect in redirect chain.
+  // True when we have seen at least one non-interal redirect.
+  bool mHaveVisibleRedirect = false;
+
+  // Pending stream filter requests which should be attached when redirecting to
+  // the real channel. Moved into `TriggerRedirectToRealChannel` when the
+  // connection is ready.
+  nsTArray<StreamFilterRequest> mStreamFilterRequests;
+
+  nsString mSrcdocData;
+  nsCOMPtr<nsIURI> mBaseURI;
+
+  mozilla::UniquePtr<mozilla::dom::LoadingSessionHistoryInfo>
+      mLoadingSessionHistoryInfo;
+
+  RefPtr<dom::WindowGlobalParent> mParentWindowContext;
+
+  // Flags from nsDocShellLoadState::LoadFlags/Type that we want to make
+  // available to the new docshell if we switch processes.
+  uint32_t mLoadStateExternalLoadFlags = 0;
+  uint32_t mLoadStateInternalLoadFlags = 0;
+  uint32_t mLoadStateLoadType = 0;
+
+  // Indicates if this load is a download.
+  bool mIsDownload = false;
+
+  // Indicates if we are loading a javascript URI.
+  bool mIsLoadingJSURI = false;
+
+  // Corresponding redirect channel registrar Id for the final channel that
+  // we want to use when redirecting the child, or doing a process switch.
+  // 0 means redirection is not started.
+  uint64_t mRedirectChannelId = 0;
+  // Set to true once we initiate the redirect to a real channel (either
+  // via a process switch or a same-process redirect, and Suspend the
+  // underlying channel.
+  bool mInitiatedRedirectToRealChannel = false;
+  // The value of GetApplyConversion on mChannel when OnStartRequest
+  // was called. We override it to false to prevent a conversion
+  // helper from being installed, but we need to restore the value
+  // later.
+  bool mOldApplyConversion = false;
+  // Set to true if any previous channel that we redirected away
+  // from had a COOP mismatch.
+  bool mHasCrossOriginOpenerPolicyMismatch = false;
+  // Set to true if we've received OnStopRequest, and shouldn't
+  // setup a reference from the ParentChannelListener to the replacement
+  // channel.
+  bool mIsFinished = false;
+
+  // The id of the currently pending load which is
+  // passed to the childChannel in order to identify it in the new process.
+  uint64_t mLoadIdentifier = 0;
+
+  Maybe<nsCString> mOriginalUriString;
+
+  // Parent-initiated loads do not support redirects to real channels.
+  bool mSupportsRedirectToRealChannel = true;
+
+  Maybe<nsCString> mRemoteTypeOverride;
+
+  // The ContentParent which this channel is currently connected to, or nullptr
+  // if connected to the parent process.
+  RefPtr<dom::ContentParent> mContentParent;
+
+  void RejectOpenPromise(nsresult aStatus, nsresult aLoadGroupStatus,
+                         bool aContinueNavigating, const char* aLocation) {
+    // It is possible for mOpenPromise to not be set if AsyncOpen failed and
+    // the DocumentChannel got canceled.
+    if (!mOpenPromiseResolved && mOpenPromise) {
+      mOpenPromise->Reject(OpenPromiseFailedType({aStatus, aLoadGroupStatus,
+                                                  aContinueNavigating}),
+                           aLocation);
+      mOpenPromiseResolved = true;
+    }
+  }
+  RefPtr<OpenPromise::Private> mOpenPromise;
+  bool mOpenPromiseResolved = false;
+
+  const bool mIsDocumentLoad;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(DocumentLoadListener, DOCUMENT_LOAD_LISTENER_IID)
+
+inline nsISupports* ToSupports(DocumentLoadListener* aObj) {
+  return static_cast<nsIInterfaceRequestor*>(aObj);
+}
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_net_DocumentChannelParent_h
diff --git a/netwerk/ipc/InputChannelThrottleQueueChild.cpp b/netwerk/ipc/InputChannelThrottleQueueChild.cpp
new file mode 100644
index 0000000000..ef7a916b79
--- /dev/null
+++ b/netwerk/ipc/InputChannelThrottleQueueChild.cpp
@@ -0,0 +1,30 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* vim:set ts=4 sw=4 sts=4 et cin: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "InputChannelThrottleQueueChild.h"
+#include "nsThreadUtils.h"
+
+namespace mozilla {
+namespace net {
+
+NS_IMPL_ISUPPORTS_INHERITED0(InputChannelThrottleQueueChild, ThrottleQueue)
+
+NS_IMETHODIMP
+InputChannelThrottleQueueChild::RecordRead(uint32_t aBytesRead) {
+  ThrottleQueue::RecordRead(aBytesRead);
+
+  RefPtr<InputChannelThrottleQueueChild> self = this;
+  NS_DispatchToMainThread(NS_NewRunnableFunction(
+      "InputChannelThrottleQueueChild::RecordRead", [self, aBytesRead]() {
+        if (self->CanSend()) {
+          Unused << self->SendRecordRead(aBytesRead);
+        }
+      }));
+  return NS_OK;
+}
+
+}  // namespace net
+}  // namespace mozilla
diff --git a/netwerk/ipc/InputChannelThrottleQueueChild.h b/netwerk/ipc/InputChannelThrottleQueueChild.h
new file mode 100644
index 0000000000..a758dac417
--- /dev/null
+++ b/netwerk/ipc/InputChannelThrottleQueueChild.h
@@ -0,0 +1,33 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* 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 InputChannelThrottleQueueChild_h__
+#define InputChannelThrottleQueueChild_h__
+
+#include "mozilla/net/PInputChannelThrottleQueueChild.h"
+#include "mozilla/net/ThrottleQueue.h"
+#include "nsISupportsImpl.h"
+
+namespace mozilla {
+namespace net {
+
+class InputChannelThrottleQueueChild final
+    : public PInputChannelThrottleQueueChild,
+      public ThrottleQueue {
+ public:
+  friend class PInputChannelThrottleQueueChild;
+  NS_DECL_ISUPPORTS_INHERITED
+
+  explicit InputChannelThrottleQueueChild() = default;
+  NS_IMETHOD RecordRead(uint32_t aBytesRead) override;
+
+ private:
+  virtual ~InputChannelThrottleQueueChild() = default;
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // InputChannelThrottleQueueChild_h__
diff --git a/netwerk/ipc/InputChannelThrottleQueueParent.cpp b/netwerk/ipc/InputChannelThrottleQueueParent.cpp
new file mode 100644
index 0000000000..d1e6e82f9f
--- /dev/null
+++ b/netwerk/ipc/InputChannelThrottleQueueParent.cpp
@@ -0,0 +1,125 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* vim:set ts=4 sw=4 sts=4 et cin: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "InputChannelThrottleQueueParent.h"
+#include "mozilla/net/SocketProcessParent.h"
+#include "nsIOService.h"
+
+namespace mozilla {
+namespace net {
+
+NS_IMPL_ADDREF(InputChannelThrottleQueueParent)
+NS_INTERFACE_MAP_BEGIN(InputChannelThrottleQueueParent)
+  NS_INTERFACE_MAP_ENTRY(nsIInputChannelThrottleQueue)
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+  NS_INTERFACE_MAP_ENTRY_CONCRETE(InputChannelThrottleQueueParent)
+NS_INTERFACE_MAP_END
+
+NS_IMETHODIMP_(MozExternalRefCountType)
+InputChannelThrottleQueueParent::Release(void) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");
+
+  if (!nsAutoRefCnt::isThreadSafe) {
+    NS_ASSERT_OWNINGTHREAD(InputChannelThrottleQueueParent);
+  }
+
+  nsrefcnt count = --mRefCnt;
+  NS_LOG_RELEASE(this, count, "InputChannelThrottleQueueParent");
+
+  if (count == 0) {
+    if (!nsAutoRefCnt::isThreadSafe) {
+      NS_ASSERT_OWNINGTHREAD(InputChannelThrottleQueueParent);
+    }
+
+    mRefCnt = 1; /* stabilize */
+    delete (this);
+    return 0;
+  }
+
+  // When ref count goes down to 1 (held internally by IPDL), it means that
+  // we are done with this ThrottleQueue. We should send a delete message
+  // to delete the InputChannelThrottleQueueChild in socket process.
+  if (count == 1 && CanSend()) {
+    mozilla::Unused << Send__delete__(this);
+    return 1;
+  }
+  return count;
+}
+
+mozilla::ipc::IPCResult InputChannelThrottleQueueParent::RecvRecordRead(
+    const uint32_t& aBytesRead) {
+  mBytesProcessed += aBytesRead;
+  return IPC_OK();
+}
+
+NS_IMETHODIMP
+InputChannelThrottleQueueParent::RecordRead(uint32_t aBytesRead) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+InputChannelThrottleQueueParent::Available(uint32_t aRemaining,
+                                           uint32_t* aAvailable) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+InputChannelThrottleQueueParent::Init(uint32_t aMeanBytesPerSecond,
+                                      uint32_t aMaxBytesPerSecond) {
+  // Can be called on any thread.
+  if (aMeanBytesPerSecond == 0 || aMaxBytesPerSecond == 0 ||
+      aMaxBytesPerSecond < aMeanBytesPerSecond) {
+    return NS_ERROR_ILLEGAL_VALUE;
+  }
+
+  mMeanBytesPerSecond = aMeanBytesPerSecond;
+  mMaxBytesPerSecond = aMaxBytesPerSecond;
+
+  RefPtr<InputChannelThrottleQueueParent> self = this;
+  gIOService->CallOrWaitForSocketProcess(
+      [self, meanBytesPerSecond(mMeanBytesPerSecond),
+       maxBytesPerSecond(mMaxBytesPerSecond)] {
+        Unused << SocketProcessParent::GetSingleton()
+                      ->SendPInputChannelThrottleQueueConstructor(
+                          self, meanBytesPerSecond, maxBytesPerSecond);
+      });
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+InputChannelThrottleQueueParent::BytesProcessed(uint64_t* aResult) {
+  *aResult = mBytesProcessed;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+InputChannelThrottleQueueParent::WrapStream(nsIInputStream* aInputStream,
+                                            nsIAsyncInputStream** aResult) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+InputChannelThrottleQueueParent::GetMeanBytesPerSecond(
+    uint32_t* aMeanBytesPerSecond) {
+  NS_ENSURE_ARG(aMeanBytesPerSecond);
+
+  *aMeanBytesPerSecond = mMeanBytesPerSecond;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+InputChannelThrottleQueueParent::GetMaxBytesPerSecond(
+    uint32_t* aMaxBytesPerSecond) {
+  NS_ENSURE_ARG(aMaxBytesPerSecond);
+
+  *aMaxBytesPerSecond = mMaxBytesPerSecond;
+  return NS_OK;
+}
+
+}  // namespace net
+}  // namespace mozilla
diff --git a/netwerk/ipc/InputChannelThrottleQueueParent.h b/netwerk/ipc/InputChannelThrottleQueueParent.h
new file mode 100644
index 0000000000..74d1a00bd7
--- /dev/null
+++ b/netwerk/ipc/InputChannelThrottleQueueParent.h
@@ -0,0 +1,51 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* 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 InputChannelThrottleQueueParent_h__
+#define InputChannelThrottleQueueParent_h__
+
+#include "nsISupportsImpl.h"
+#include "nsIThrottledInputChannel.h"
+#include "mozilla/net/PInputChannelThrottleQueueParent.h"
+
+namespace mozilla {
+namespace net {
+
+#define INPUT_CHANNEL_THROTTLE_QUEUE_PARENT_IID      \
+  {                                                  \
+    0x4f151655, 0x70b3, 0x4350, {                    \
+      0x9b, 0xd9, 0xe3, 0x2b, 0xe5, 0xeb, 0xb2, 0x9e \
+    }                                                \
+  }
+
+class InputChannelThrottleQueueParent final
+    : public PInputChannelThrottleQueueParent,
+      public nsIInputChannelThrottleQueue {
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIINPUTCHANNELTHROTTLEQUEUE
+  NS_DECLARE_STATIC_IID_ACCESSOR(INPUT_CHANNEL_THROTTLE_QUEUE_PARENT_IID)
+
+  friend class PInputChannelThrottleQueueParent;
+
+  explicit InputChannelThrottleQueueParent() = default;
+  mozilla::ipc::IPCResult RecvRecordRead(const uint32_t& aBytesRead);
+  void ActorDestroy(ActorDestroyReason aWhy) override {}
+
+ private:
+  virtual ~InputChannelThrottleQueueParent() = default;
+
+  uint64_t mBytesProcessed{0};
+  uint32_t mMeanBytesPerSecond{0};
+  uint32_t mMaxBytesPerSecond{0};
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(InputChannelThrottleQueueParent,
+                              INPUT_CHANNEL_THROTTLE_QUEUE_PARENT_IID)
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // InputChannelThrottleQueueParent_h__
diff --git a/netwerk/ipc/NeckoChannelParams.ipdlh b/netwerk/ipc/NeckoChannelParams.ipdlh
new file mode 100644
index 0000000000..0aaacd2bd0
--- /dev/null
+++ b/netwerk/ipc/NeckoChannelParams.ipdlh
@@ -0,0 +1,608 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 ft=c: */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include protocol PHttpChannel;
+include ClientIPCTypes;
+include URIParams;
+include IPCServiceWorkerDescriptor;
+include IPCStream;
+include PBackgroundSharedTypes;
+include DOMTypes;
+include ProtocolTypes;
+
+include "mozilla/dom/FetchIPCTypes.h";
+include "mozilla/dom/PropertyBagUtils.h";
+include "mozilla/dom/ReferrerInfoUtils.h";
+include "mozilla/ipc/URIUtils.h";
+include "mozilla/net/CacheInfoIPCTypes.h";
+include "mozilla/AntiTrackingIPCUtils.h";
+include "mozilla/net/ClassOfService.h";
+
+using mozilla::OriginAttributes from "mozilla/ipc/BackgroundUtils.h";
+using mozilla::net::RequestHeaderTuples from "mozilla/net/PHttpChannelParams.h";
+using struct nsHttpAtom from "nsHttp.h";
+using class mozilla::net::nsHttpResponseHead from "nsHttpResponseHead.h";
+using class mozilla::TimeStamp from "mozilla/TimeStamp.h";
+[RefCounted] using class nsIPropertyBag2 from "nsIPropertyBag2.h";
+[RefCounted] using class nsDOMNavigationTiming from "nsDOMNavigationTiming.h";
+[RefCounted] using class nsDocShellLoadState from "nsDocShellLoadState.h";
+using nsContentPolicyType from "nsIContentPolicy.h";
+using mozilla::net::PreferredAlternativeDataDeliveryTypeIPC from "nsICacheInfoChannel.h";
+using nsILoadInfo::CrossOriginEmbedderPolicy from "nsILoadInfo.h";
+using nsILoadInfo::StoragePermissionState from "nsILoadInfo.h";
+using struct mozilla::dom::LoadingSessionHistoryInfo from "mozilla/dom/SessionHistoryEntry.h";
+using mozilla::dom::RequestMode from "mozilla/dom/RequestBinding.h";
+using mozilla::net::LinkHeader from "nsNetUtil.h";
+
+namespace mozilla {
+namespace net {
+
+//-----------------------------------------------------------------------------
+// CookieJarSettings IPDL structs
+//-----------------------------------------------------------------------------
+
+struct CookiePermissionData
+{
+  PrincipalInfo principalInfo;
+  uint32_t cookiePermission;
+};
+
+struct CookieJarSettingsArgs
+{
+  // Copy of the cookie jar settings for the top-level document.
+  uint32_t cookieBehavior;
+  bool isFirstPartyIsolated;
+  bool shouldResistFingerprinting;
+  bool isOnContentBlockingAllowList;
+  CookiePermissionData[] cookiePermissions;
+  bool isFixed;
+  nsString partitionKey;
+  bool hasFingerprintingRandomizationKey;
+  uint8_t[] fingerprintingRandomizationKey;
+};
+
+//-----------------------------------------------------------------------------
+// Preferrer alternative data type
+//-----------------------------------------------------------------------------
+
+struct PreferredAlternativeDataTypeParams
+{
+  nsCString type;
+  nsCString contentType;
+  PreferredAlternativeDataDeliveryTypeIPC deliverAltData;
+};
+
+//-----------------------------------------------------------------------------
+// LoadInfo IPDL structs
+//-----------------------------------------------------------------------------
+
+struct RedirectHistoryEntryInfo
+{
+  PrincipalInfo       principalInfo;
+  URIParams?          referrerUri;
+  nsCString           remoteAddress;
+};
+
+struct InterceptionInfoArg
+{
+  PrincipalInfo?              triggeringPrincipalInfo;
+  nsContentPolicyType         contentPolicyType;
+  RedirectHistoryEntryInfo[]  redirectChain;
+  bool                        fromThirdParty;
+};
+
+struct LoadInfoArgs
+{
+  PrincipalInfo?              requestingPrincipalInfo;
+  PrincipalInfo               triggeringPrincipalInfo;
+  PrincipalInfo?              principalToInheritInfo;
+  PrincipalInfo?              topLevelPrincipalInfo;
+  URIParams?                  resultPrincipalURI;
+  nsCString                   triggeringRemoteType;
+  nsID                        sandboxedNullPrincipalID;
+  uint32_t                    securityFlags;
+  uint32_t                    sandboxFlags;
+  uint32_t                    triggeringSandboxFlags;
+  nsContentPolicyType         contentPolicyType;
+  uint32_t                    tainting;
+  bool                        blockAllMixedContent;
+  bool                        upgradeInsecureRequests;
+  bool                        browserUpgradeInsecureRequests;
+  bool                        browserDidUpgradeInsecureRequests;
+  bool                        browserWouldUpgradeInsecureRequests;
+  bool                        forceAllowDataURI;
+  bool                        allowInsecureRedirectToDataURI;
+  bool                        skipContentPolicyCheckForWebRequest;
+  bool                        originalFrameSrcLoad;
+  bool                        forceInheritPrincipalDropped;
+  uint64_t                    innerWindowID;
+  uint64_t                    browsingContextID;
+  uint64_t                    frameBrowsingContextID;
+  bool                        initialSecurityCheckDone;
+  bool                        isInThirdPartyContext;
+  bool?                       isThirdPartyContextToTopWindow;
+  bool                        isFormSubmission;
+  bool                        sendCSPViolationEvents;
+  OriginAttributes            originAttributes;
+  RedirectHistoryEntryInfo[]  redirectChainIncludingInternalRedirects;
+  RedirectHistoryEntryInfo[]  redirectChain;
+  bool                        hasInjectedCookieForCookieBannerHandling;
+
+  /**
+   * ClientInfo structure representing the window or worker that triggered
+   * this network request.  May be Nothing if its a system internal request.
+   */
+  IPCClientInfo?              clientInfo;
+
+  /**
+   * Non-subresource requests will result in the creation of a window or
+   * worker client.  The reserved and initial ClientInfo values represent
+   * this resulting client.  An initial ClientInfo represents an initial
+   * about:blank window that will be re-used while a reserved ClientInfo
+   * represents a to-be-newly-created window/worker.
+   */
+  IPCClientInfo?              reservedClientInfo;
+  IPCClientInfo?              initialClientInfo;
+
+  /**
+   * Subresource loads may have a controller set based on their owning
+   * window/worker client.  We must send this across IPC to support
+   * performing interception in the parent.
+   */
+  IPCServiceWorkerDescriptor? controller;
+
+  nsCString[]                 corsUnsafeHeaders;
+  bool                        forcePreflight;
+  bool                        isPreflight;
+  bool                        loadTriggeredFromExternal;
+  bool                        serviceWorkerTaintingSynthesized;
+  bool                        documentHasUserInteracted;
+  bool allowListFutureDocumentsCreatedFromThisRedirectChain;
+  bool needForCheckingAntiTrackingHeuristic;
+  nsString                    cspNonce;
+  bool                        skipContentSniffing;
+  uint32_t                    httpsOnlyStatus;
+  bool                        hstsStatus;
+  bool                        hasValidUserGestureActivation;
+  bool                        allowDeprecatedSystemRequests;
+  bool                        isInDevToolsContext;
+  bool                        parserCreatedScript;
+  bool                        isFromProcessingFrameAttributes;
+  bool                        isMediaRequest;
+  bool                        isMediaInitialRequest;
+  bool                        isFromObjectOrEmbed;
+  CookieJarSettingsArgs       cookieJarSettings;
+  uint32_t                    requestBlockingReason;
+  CSPInfo?                    cspToInheritInfo;
+  StoragePermissionState      storagePermission;
+  bool                        isMetaRefresh;
+  CrossOriginEmbedderPolicy   loadingEmbedderPolicy;
+  bool                        originTrialCoepCredentiallessEnabledForTopLevel;
+  nullable nsIURI             unstrippedURI;
+  InterceptionInfoArg?        interceptionInfo;
+};
+
+/**
+ * This structure is used to carry selected properties of a LoadInfo
+ * object to child processes to merge LoadInfo changes from the parent
+ * process.  We don't want to use LoadInfoArgs for that since it's
+ * too huge and we only care about small subpart of properties anyway.
+ */
+struct ParentLoadInfoForwarderArgs
+{
+  // WebExtextensions' WebRequest API allows extensions to intercept and
+  // redirect a channel to a data URI. This modifications happens in
+  // the parent and needs to be mirrored to the child so that security
+  // checks can pass.
+  bool allowInsecureRedirectToDataURI;
+
+  // The ServiceWorker controller that may be set in the parent when
+  // interception occurs.
+  IPCServiceWorkerDescriptor? controller;
+
+  // The service worker may synthesize a Response with a particular
+  // tainting value.
+  uint32_t tainting;
+
+  // This flag is used for any browsing context where we should not sniff
+  // the content type. E.g if an iframe has the XCTO nosniff header, then
+  // that flag is set to true so we skip content sniffing for that browsing
+  bool skipContentSniffing;
+
+  uint32_t httpsOnlyStatus;
+
+  bool hstsStatus;
+
+  // Returns true if at the time of the loadinfo construction the document
+  // that triggered this load has the bit hasValidTransientUserGestureActivation
+  // set or the load was triggered from External. (Mostly this bool is used
+  // in the context of Sec-Fetch-User.)
+  bool hasValidUserGestureActivation;
+
+  // The SystemPrincipal is disallowed to make requests to the public web
+  // and all requests will be cancelled. Setting this flag to true prevents
+  // the request from being cancelled.
+  bool allowDeprecatedSystemRequests;
+
+  bool isInDevToolsContext;
+
+  // Only ever returns true if the loadinfo is of TYPE_SCRIPT and
+  // the script was created by the HTML parser.
+  bool parserCreatedScript;
+
+  // Sandbox Flags of the Document that triggered the load
+  uint32_t triggeringSandboxFlags;
+
+  // We must also note that the tainting value was explicitly set
+  // by the service worker.
+  bool serviceWorkerTaintingSynthesized;
+
+  bool documentHasUserInteracted;
+  bool allowListFutureDocumentsCreatedFromThisRedirectChain;
+
+  CookieJarSettingsArgs? cookieJarSettings;
+
+  uint32_t requestBlockingReason;
+
+  StoragePermissionState storagePermission;
+
+  bool isMetaRefresh;
+
+  bool? isThirdPartyContextToTopWindow;
+
+  bool isInThirdPartyContext;
+
+  nullable nsIURI unstrippedURI;
+
+  // IMPORTANT: when you add new properites here you must also update
+  // LoadInfoToParentLoadInfoForwarder and MergeParentLoadInfoForwarder
+  // in BackgroundUtils.cpp/.h!
+};
+
+/**
+ * This structure is used to carry selected properties of a LoadInfo
+ * object to the parent process that might have changed in the child
+ * during a redirect.  We don't want to use LoadInfoArgs for that since
+ * it's too huge and we only care about small subpart of properties
+ * anyway.
+ */
+struct ChildLoadInfoForwarderArgs
+{
+  // The reserved and initial ClientInfo values may change during a
+  // redirect if the new channel is cross-origin to the old channel.
+  IPCClientInfo? reservedClientInfo;
+  IPCClientInfo? initialClientInfo;
+
+  // The ServiceWorker controller may be cleared in the child during
+  // a redirect.
+  IPCServiceWorkerDescriptor? controller;
+
+  uint32_t requestBlockingReason;
+};
+
+//-----------------------------------------------------------------------------
+// HTTP IPDL structs
+//-----------------------------------------------------------------------------
+
+struct CorsPreflightArgs
+{
+  nsCString[]   unsafeHeaders;
+};
+
+struct HttpChannelOpenArgs
+{
+  nullable nsIURI             uri;
+  // - TODO: bug 571161: unclear if any HTTP channel clients ever
+  // set originalURI != uri (about:credits?); also not clear if
+  // chrome channel would ever need to know.  Get rid of next arg?
+  nullable nsIURI             original;
+  nullable nsIURI             doc;
+  nullable nsIReferrerInfo    referrerInfo;
+  nullable nsIURI             apiRedirectTo;
+  nullable nsIURI             topWindowURI;
+  RequestHeaderTuples         requestHeaders;
+  PreferredAlternativeDataTypeParams[] preferredAlternativeTypes;
+  TimeStamp                   launchServiceWorkerStart;
+  TimeStamp                   launchServiceWorkerEnd;
+  TimeStamp                   dispatchFetchEventStart;
+  TimeStamp                   dispatchFetchEventEnd;
+  TimeStamp                   handleFetchEventStart;
+  TimeStamp                   handleFetchEventEnd;
+  TimeStamp                   navigationStartTimeStamp;
+  uint64_t                    startPos;
+  uint64_t                    requestContextID;
+  uint64_t                    channelId;
+  uint64_t                    contentWindowId;
+  uint64_t                    browserId;
+  uint64_t                    earlyHintPreloaderId;
+  nsCString                   requestMethod;
+  ClassOfService              classOfService;
+  nsCString                   entityID;
+  nsCString                   appCacheClientID;
+  CorsPreflightArgs?          preflightArgs;
+  nsCString                   contentTypeHint;
+  nsString                    integrityMetadata;
+  IPCStream?                  uploadStream;
+  LoadInfoArgs?               loadInfo;
+  uint32_t                    loadFlags;
+  uint32_t                    thirdPartyFlags;
+  uint32_t                    tlsFlags;
+  uint32_t                    cacheKey;
+  uint32_t                    initialRwin;
+  uint32_t                    redirectMode;
+  int16_t                     priority;
+  bool                        uploadStreamHasHeaders;
+  bool                        allowSTS;
+  bool                        resumeAt;
+  bool                        allowSpdy;
+  bool                        allowHttp3;
+  bool                        allowAltSvc;
+  bool                        beConservative;
+  bool                        bypassProxy;
+  bool                        blockAuthPrompt;
+  bool                        allowStaleCacheContent;
+  RequestMode                 requestMode;
+  bool                        forceValidateCacheContent;
+  bool                        preferCacheLoadOverBypass;
+  bool                        forceMainDocumentChannel;
+  uint8_t                     redirectionLimit;
+  nsString                    classicScriptHintCharset;
+  nsString                    documentCharacterSet;
+};
+
+struct HttpChannelConnectArgs
+{
+  uint32_t registrarId;
+};
+
+union HttpChannelCreationArgs
+{
+  HttpChannelOpenArgs;      // For AsyncOpen: the common case.
+  HttpChannelConnectArgs;   // Used for redirected-to channels
+};
+
+struct ProxyInfoCloneArgs
+{
+  nsCString type;
+  nsCString host;
+  int32_t port;
+  nsCString username;
+  nsCString password;
+  uint32_t flags;
+  uint32_t timeout;
+  uint32_t resolveFlags;
+  nsCString proxyAuthorizationHeader;
+  nsCString connectionIsolationKey;
+};
+
+struct HttpConnectionInfoCloneArgs
+{
+  nsCString host;
+  int32_t port;
+  nsCString npnToken;
+  nsCString username;
+  OriginAttributes originAttributes;
+  bool endToEndSSL;
+  nsCString routedHost;
+  int32_t routedPort;
+  bool anonymous;
+  bool aPrivate; // use prefix to avoid code generation error
+  bool insecureScheme;
+  bool noSpdy;
+  bool beConservative;
+  bool bypassProxy;
+  bool anonymousAllowClientCert;
+  bool fallbackConnection;
+  uint32_t tlsFlags;
+  bool isolated;
+  bool isTrrServiceChannel;
+  uint8_t trrMode;
+  bool isIPv4Disabled;
+  bool isIPv6Disabled;
+  nsCString topWindowOrigin;
+  bool isHttp3;
+  bool webTransport;
+  bool hasIPHintAddress;
+  nsCString echConfig;
+  ProxyInfoCloneArgs[] proxyInfo;
+};
+
+struct ConsoleReportCollected {
+  uint32_t errorFlags;
+  nsCString category;
+  uint32_t propertiesFile;
+  nsCString sourceFileURI;
+  uint32_t lineNumber;
+  uint32_t columnNumber;
+  nsCString messageName;
+  nsString[] stringParams;
+};
+
+struct CookieStruct
+{
+  nsCString name;
+  nsCString value;
+  nsCString host;
+  nsCString path;
+  int64_t   expiry;
+  int64_t   lastAccessed;
+  int64_t   creationTime;
+  bool      isHttpOnly;
+  bool      isSession;
+  bool      isSecure;
+  int32_t   sameSite;
+  int32_t   rawSameSite;
+  uint8_t   schemeMap;
+};
+
+struct DocumentCreationArgs {
+  bool uriModified;
+  bool isXFOError;
+};
+
+struct ObjectCreationArgs {
+  uint64_t embedderInnerWindowId;
+  uint32_t loadFlags;
+  nsContentPolicyType contentPolicyType;
+  bool isUrgentStart;
+};
+
+union DocumentChannelElementCreationArgs {
+  DocumentCreationArgs;
+  ObjectCreationArgs;
+};
+
+struct DocumentChannelCreationArgs {
+  nsDocShellLoadState loadState;
+  TimeStamp asyncOpenTime;
+  uint64_t channelId;
+  uint32_t cacheKey;
+  nullable nsDOMNavigationTiming timing;
+  IPCClientInfo? initialClientInfo;
+  DocumentChannelElementCreationArgs elementCreationArgs;
+  uint64_t parentInitiatedNavigationEpoch;
+};
+
+struct EarlyHintConnectArgs {
+  LinkHeader link;
+  uint64_t earlyHintPreloaderId;
+};
+
+struct RedirectToRealChannelArgs {
+  uint32_t registrarId;
+  nullable nsIURI uri;
+  uint32_t newLoadFlags;
+  ReplacementChannelConfigInit? init;
+  LoadInfoArgs? loadInfo;
+  uint64_t channelId;
+  nullable nsIURI originalURI;
+  uint32_t redirectMode;
+  uint32_t redirectFlags;
+  uint32_t? contentDisposition;
+  nsString? contentDispositionFilename;
+  nullable nsIPropertyBag2 properties;
+  uint32_t loadStateExternalLoadFlags;
+  uint32_t loadStateInternalLoadFlags;
+  uint32_t loadStateLoadType;
+  nullable nsDOMNavigationTiming timing;
+  nsString srcdocData;
+  nullable nsIURI baseUri;
+  LoadingSessionHistoryInfo? loadingSessionHistoryInfo;
+  uint64_t loadIdentifier;
+  nsCString? originalUriString;
+  EarlyHintConnectArgs[] earlyHints;
+  uint32_t earlyHintLinkType;
+};
+
+struct TimingStructArgs {
+  TimeStamp domainLookupStart;
+  TimeStamp domainLookupEnd;
+  TimeStamp connectStart;
+  TimeStamp tcpConnectEnd;
+  TimeStamp secureConnectionStart;
+  TimeStamp connectEnd;
+  TimeStamp requestStart;
+  TimeStamp responseStart;
+  TimeStamp responseEnd;
+};
+
+struct ResourceTimingStructArgs {
+  TimeStamp domainLookupStart;
+  TimeStamp domainLookupEnd;
+  TimeStamp connectStart;
+  TimeStamp tcpConnectEnd;
+  TimeStamp secureConnectionStart;
+  TimeStamp connectEnd;
+  TimeStamp requestStart;
+  TimeStamp responseStart;
+  TimeStamp responseEnd;
+  TimeStamp fetchStart;
+  TimeStamp redirectStart;
+  TimeStamp redirectEnd;
+  uint64_t transferSize;
+  uint64_t encodedBodySize;
+  nsCString protocolVersion;
+
+  // Not actually part of resource timing, but not part of the transaction
+  // timings either. These need to be passed to HttpChannelChild along with
+  // the rest of the timings so the timing information in the child is complete.
+  TimeStamp cacheReadStart;
+  TimeStamp cacheReadEnd;
+
+  TimeStamp transactionPending;
+};
+
+struct HttpActivity
+{
+  nsCString host;
+  int32_t port;
+  bool endToEndSSL;
+};
+
+struct HttpConnectionActivity
+{
+  nsCString connInfoKey;
+  nsCString host;
+  int32_t port;
+  bool ssl;
+  bool hasECH;
+  bool isHttp3;
+};
+
+union HttpActivityArgs
+{
+  uint64_t;
+  HttpActivity;
+  HttpConnectionActivity;
+};
+
+struct TransactionObserverResult
+{
+  bool versionOk;
+  bool authOk;
+  nsresult closeReason;
+};
+
+struct SpeculativeConnectionOverriderArgs {
+  uint32_t parallelSpeculativeConnectLimit;
+  bool ignoreIdle;
+  bool isFromPredictor;
+  bool allow1918;
+};
+
+//-----------------------------------------------------------------------------
+// GIO IPDL structs
+//-----------------------------------------------------------------------------
+
+struct GIOChannelOpenArgs
+{
+  URIParams                 uri;
+  uint64_t                  startPos;
+  nsCString                 entityID;
+  IPCStream?                uploadStream;
+  LoadInfoArgs?             loadInfo;
+  uint32_t                  loadFlags;
+};
+
+struct GIOChannelConnectArgs
+{
+  uint32_t channelId;
+};
+
+union GIOChannelCreationArgs
+{
+  GIOChannelOpenArgs;      // For AsyncOpen: the common case.
+  GIOChannelConnectArgs;   // Used for redirected-to channels
+};
+
+struct RemoteStreamInfo {
+  nullable nsIInputStream inputStream;
+  nsCString contentType;
+  int64_t contentLength;
+};
+} // namespace net
+} // namespace mozilla
diff --git a/netwerk/ipc/NeckoChild.cpp b/netwerk/ipc/NeckoChild.cpp
new file mode 100644
index 0000000000..7a45017582
--- /dev/null
+++ b/netwerk/ipc/NeckoChild.cpp
@@ -0,0 +1,344 @@
+
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsHttp.h"
+#include "mozilla/net/NeckoChild.h"
+#include "mozilla/dom/ContentChild.h"
+#include "mozilla/dom/BrowserChild.h"
+#include "mozilla/net/HttpChannelChild.h"
+#include "mozilla/net/ChildDNSService.h"
+#include "mozilla/net/CookieServiceChild.h"
+#include "mozilla/net/DataChannelChild.h"
+#ifdef MOZ_WIDGET_GTK
+#  include "mozilla/net/GIOChannelChild.h"
+#endif
+#include "mozilla/net/FileChannelChild.h"
+#include "mozilla/net/WebSocketChannelChild.h"
+#include "mozilla/net/WebSocketEventListenerChild.h"
+#include "mozilla/net/DNSRequestChild.h"
+#include "mozilla/net/IPCTransportProvider.h"
+#include "mozilla/dom/network/TCPSocketChild.h"
+#include "mozilla/dom/network/TCPServerSocketChild.h"
+#include "mozilla/dom/network/UDPSocketChild.h"
+#include "mozilla/net/AltDataOutputStreamChild.h"
+#include "mozilla/net/SocketProcessBridgeChild.h"
+#ifdef MOZ_WEBRTC
+#  include "mozilla/net/StunAddrsRequestChild.h"
+#  include "mozilla/net/WebrtcTCPSocketChild.h"
+#endif
+
+#include "SerializedLoadContext.h"
+#include "nsGlobalWindow.h"
+#include "nsIOService.h"
+#include "nsINetworkPredictor.h"
+#include "nsINetworkPredictorVerifier.h"
+#include "nsINetworkLinkService.h"
+#include "nsQueryObject.h"
+#include "mozilla/ipc/URIUtils.h"
+#include "nsNetUtil.h"
+#include "SimpleChannel.h"
+
+using mozilla::dom::TCPServerSocketChild;
+using mozilla::dom::TCPSocketChild;
+using mozilla::dom::UDPSocketChild;
+
+namespace mozilla {
+namespace net {
+
+PNeckoChild* gNeckoChild = nullptr;
+
+// C++ file contents
+
+NeckoChild::~NeckoChild() {
+  // Send__delete__(gNeckoChild);
+  gNeckoChild = nullptr;
+}
+
+void NeckoChild::InitNeckoChild() {
+  if (!IsNeckoChild()) {
+    MOZ_ASSERT(false, "InitNeckoChild called by non-child!");
+    return;
+  }
+
+  if (!gNeckoChild) {
+    mozilla::dom::ContentChild* cpc =
+        mozilla::dom::ContentChild::GetSingleton();
+    NS_ASSERTION(cpc, "Content Protocol is NULL!");
+    if (NS_WARN_IF(cpc->IsShuttingDown())) {
+      return;
+    }
+    RefPtr<NeckoChild> child = new NeckoChild();
+    gNeckoChild = cpc->SendPNeckoConstructor(child);
+    NS_ASSERTION(gNeckoChild, "PNecko Protocol init failed!");
+  }
+}
+
+PStunAddrsRequestChild* NeckoChild::AllocPStunAddrsRequestChild() {
+  // We don't allocate here: instead we always use IPDL constructor that takes
+  // an existing object
+  MOZ_ASSERT_UNREACHABLE(
+      "AllocPStunAddrsRequestChild should not be called "
+      "on child");
+  return nullptr;
+}
+
+bool NeckoChild::DeallocPStunAddrsRequestChild(PStunAddrsRequestChild* aActor) {
+#ifdef MOZ_WEBRTC
+  StunAddrsRequestChild* p = static_cast<StunAddrsRequestChild*>(aActor);
+  p->ReleaseIPDLReference();
+#endif
+  return true;
+}
+
+PWebrtcTCPSocketChild* NeckoChild::AllocPWebrtcTCPSocketChild(
+    const Maybe<TabId>& tabId) {
+  // We don't allocate here: instead we always use IPDL constructor that takes
+  // an existing object
+  MOZ_ASSERT_UNREACHABLE(
+      "AllocPWebrtcTCPSocketChild should not be called on"
+      " child");
+  return nullptr;
+}
+
+bool NeckoChild::DeallocPWebrtcTCPSocketChild(PWebrtcTCPSocketChild* aActor) {
+#ifdef MOZ_WEBRTC
+  WebrtcTCPSocketChild* child = static_cast<WebrtcTCPSocketChild*>(aActor);
+  child->ReleaseIPDLReference();
+#endif
+  return true;
+}
+
+PAltDataOutputStreamChild* NeckoChild::AllocPAltDataOutputStreamChild(
+    const nsACString& type, const int64_t& predictedSize,
+    PHttpChannelChild* channel) {
+  // We don't allocate here: see HttpChannelChild::OpenAlternativeOutputStream()
+  MOZ_ASSERT_UNREACHABLE("AllocPAltDataOutputStreamChild should not be called");
+  return nullptr;
+}
+
+bool NeckoChild::DeallocPAltDataOutputStreamChild(
+    PAltDataOutputStreamChild* aActor) {
+  AltDataOutputStreamChild* child =
+      static_cast<AltDataOutputStreamChild*>(aActor);
+  child->ReleaseIPDLReference();
+  return true;
+}
+
+#ifdef MOZ_WIDGET_GTK
+PGIOChannelChild* NeckoChild::AllocPGIOChannelChild(
+    PBrowserChild* aBrowser, const SerializedLoadContext& aSerialized,
+    const GIOChannelCreationArgs& aOpenArgs) {
+  // We don't allocate here: see GIOChannelChild::AsyncOpen()
+  MOZ_CRASH("AllocPGIOChannelChild should not be called");
+  return nullptr;
+}
+
+bool NeckoChild::DeallocPGIOChannelChild(PGIOChannelChild* channel) {
+  MOZ_ASSERT(IsNeckoChild(), "DeallocPGIOChannelChild called by non-child!");
+
+  GIOChannelChild* child = static_cast<GIOChannelChild*>(channel);
+  child->ReleaseIPDLReference();
+  return true;
+}
+#endif
+
+PCookieServiceChild* NeckoChild::AllocPCookieServiceChild() {
+  // We don't allocate here: see CookieService::GetSingleton()
+  MOZ_ASSERT_UNREACHABLE("AllocPCookieServiceChild should not be called");
+  return nullptr;
+}
+
+bool NeckoChild::DeallocPCookieServiceChild(PCookieServiceChild* cs) {
+  NS_ASSERTION(IsNeckoChild(),
+               "DeallocPCookieServiceChild called by non-child!");
+
+  CookieServiceChild* p = static_cast<CookieServiceChild*>(cs);
+  p->Release();
+  return true;
+}
+
+PWebSocketChild* NeckoChild::AllocPWebSocketChild(
+    PBrowserChild* browser, const SerializedLoadContext& aSerialized,
+    const uint32_t& aSerial) {
+  MOZ_ASSERT_UNREACHABLE("AllocPWebSocketChild should not be called");
+  return nullptr;
+}
+
+bool NeckoChild::DeallocPWebSocketChild(PWebSocketChild* child) {
+  WebSocketChannelChild* p = static_cast<WebSocketChannelChild*>(child);
+  p->ReleaseIPDLReference();
+  return true;
+}
+
+PWebSocketEventListenerChild* NeckoChild::AllocPWebSocketEventListenerChild(
+    const uint64_t& aInnerWindowID) {
+  nsCOMPtr<nsISerialEventTarget> target;
+  if (nsGlobalWindowInner* win =
+          nsGlobalWindowInner::GetInnerWindowWithId(aInnerWindowID)) {
+    target = win->EventTargetFor(TaskCategory::Other);
+  }
+
+  RefPtr<WebSocketEventListenerChild> c =
+      new WebSocketEventListenerChild(aInnerWindowID, target);
+
+  return c.forget().take();
+}
+
+bool NeckoChild::DeallocPWebSocketEventListenerChild(
+    PWebSocketEventListenerChild* aActor) {
+  RefPtr<WebSocketEventListenerChild> c =
+      dont_AddRef(static_cast<WebSocketEventListenerChild*>(aActor));
+  MOZ_ASSERT(c);
+  return true;
+}
+
+PSimpleChannelChild* NeckoChild::AllocPSimpleChannelChild(
+    const uint32_t& channelId) {
+  MOZ_ASSERT_UNREACHABLE("Should never get here");
+  return nullptr;
+}
+
+bool NeckoChild::DeallocPSimpleChannelChild(PSimpleChannelChild* child) {
+  static_cast<SimpleChannelChild*>(child)->Release();
+  return true;
+}
+
+PTCPSocketChild* NeckoChild::AllocPTCPSocketChild(const nsAString& host,
+                                                  const uint16_t& port) {
+  TCPSocketChild* p = new TCPSocketChild(host, port, nullptr);
+  p->AddIPDLReference();
+  return p;
+}
+
+bool NeckoChild::DeallocPTCPSocketChild(PTCPSocketChild* child) {
+  TCPSocketChild* p = static_cast<TCPSocketChild*>(child);
+  p->ReleaseIPDLReference();
+  return true;
+}
+
+PTCPServerSocketChild* NeckoChild::AllocPTCPServerSocketChild(
+    const uint16_t& aLocalPort, const uint16_t& aBacklog,
+    const bool& aUseArrayBuffers) {
+  MOZ_ASSERT_UNREACHABLE("AllocPTCPServerSocket should not be called");
+  return nullptr;
+}
+
+bool NeckoChild::DeallocPTCPServerSocketChild(PTCPServerSocketChild* child) {
+  TCPServerSocketChild* p = static_cast<TCPServerSocketChild*>(child);
+  p->ReleaseIPDLReference();
+  return true;
+}
+
+PUDPSocketChild* NeckoChild::AllocPUDPSocketChild(nsIPrincipal* aPrincipal,
+                                                  const nsACString& aFilter) {
+  MOZ_ASSERT_UNREACHABLE("AllocPUDPSocket should not be called");
+  return nullptr;
+}
+
+bool NeckoChild::DeallocPUDPSocketChild(PUDPSocketChild* child) {
+  UDPSocketChild* p = static_cast<UDPSocketChild*>(child);
+  p->ReleaseIPDLReference();
+  return true;
+}
+
+PTransportProviderChild* NeckoChild::AllocPTransportProviderChild() {
+  // This refcount is transferred to the receiver of the message that
+  // includes the PTransportProviderChild actor.
+  RefPtr<TransportProviderChild> res = new TransportProviderChild();
+
+  return res.forget().take();
+}
+
+bool NeckoChild::DeallocPTransportProviderChild(
+    PTransportProviderChild* aActor) {
+  return true;
+}
+
+/* Predictor Messages */
+mozilla::ipc::IPCResult NeckoChild::RecvPredOnPredictPrefetch(
+    nsIURI* aURI, const uint32_t& aHttpStatus) {
+  MOZ_ASSERT(NS_IsMainThread(),
+             "PredictorChild::RecvOnPredictPrefetch "
+             "off main thread.");
+  if (!aURI) {
+    return IPC_FAIL(this, "aURI is null");
+  }
+
+  // Get the current predictor
+  nsresult rv = NS_OK;
+  nsCOMPtr<nsINetworkPredictorVerifier> predictor =
+      do_GetService("@mozilla.org/network/predictor;1", &rv);
+  NS_ENSURE_SUCCESS(rv, IPC_FAIL_NO_REASON(this));
+
+  predictor->OnPredictPrefetch(aURI, aHttpStatus);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoChild::RecvPredOnPredictPreconnect(nsIURI* aURI) {
+  MOZ_ASSERT(NS_IsMainThread(),
+             "PredictorChild::RecvOnPredictPreconnect "
+             "off main thread.");
+  if (!aURI) {
+    return IPC_FAIL(this, "aURI is null");
+  }
+  // Get the current predictor
+  nsresult rv = NS_OK;
+  nsCOMPtr<nsINetworkPredictorVerifier> predictor =
+      do_GetService("@mozilla.org/network/predictor;1", &rv);
+  NS_ENSURE_SUCCESS(rv, IPC_FAIL_NO_REASON(this));
+
+  predictor->OnPredictPreconnect(aURI);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoChild::RecvPredOnPredictDNS(nsIURI* aURI) {
+  MOZ_ASSERT(NS_IsMainThread(),
+             "PredictorChild::RecvOnPredictDNS off "
+             "main thread.");
+  if (!aURI) {
+    return IPC_FAIL(this, "aURI is null");
+  }
+  // Get the current predictor
+  nsresult rv = NS_OK;
+  nsCOMPtr<nsINetworkPredictorVerifier> predictor =
+      do_GetService("@mozilla.org/network/predictor;1", &rv);
+  NS_ENSURE_SUCCESS(rv, IPC_FAIL_NO_REASON(this));
+
+  predictor->OnPredictDNS(aURI);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoChild::RecvSpeculativeConnectRequest() {
+  nsCOMPtr<nsIObserverService> obsService = services::GetObserverService();
+  if (obsService) {
+    obsService->NotifyObservers(nullptr, "speculative-connect-request",
+                                nullptr);
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoChild::RecvNetworkChangeNotification(
+    nsCString const& type) {
+  nsCOMPtr<nsIObserverService> obsService = services::GetObserverService();
+  if (obsService) {
+    obsService->NotifyObservers(nullptr, NS_NETWORK_LINK_TOPIC,
+                                NS_ConvertUTF8toUTF16(type).get());
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoChild::RecvSetTRRDomain(const nsCString& domain) {
+  RefPtr<net::ChildDNSService> dnsServiceChild =
+      dont_AddRef(net::ChildDNSService::GetSingleton());
+  if (dnsServiceChild) {
+    dnsServiceChild->SetTRRDomain(domain);
+  }
+  return IPC_OK();
+}
+
+}  // namespace net
+}  // namespace mozilla
diff --git a/netwerk/ipc/NeckoChild.h b/netwerk/ipc/NeckoChild.h
new file mode 100644
index 0000000000..2434c02126
--- /dev/null
+++ b/netwerk/ipc/NeckoChild.h
@@ -0,0 +1,93 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_NeckoChild_h
+#define mozilla_net_NeckoChild_h
+
+#include "mozilla/net/PNeckoChild.h"
+#include "mozilla/net/NeckoCommon.h"
+
+namespace mozilla {
+namespace net {
+
+// Header file contents
+class NeckoChild : public PNeckoChild {
+  friend class PNeckoChild;
+
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(NeckoChild, override)
+
+  NeckoChild() = default;
+
+  static void InitNeckoChild();
+
+ protected:
+  virtual ~NeckoChild();
+
+  PStunAddrsRequestChild* AllocPStunAddrsRequestChild();
+  bool DeallocPStunAddrsRequestChild(PStunAddrsRequestChild* aActor);
+
+  PWebrtcTCPSocketChild* AllocPWebrtcTCPSocketChild(const Maybe<TabId>& tabId);
+  bool DeallocPWebrtcTCPSocketChild(PWebrtcTCPSocketChild* aActor);
+
+  PAltDataOutputStreamChild* AllocPAltDataOutputStreamChild(
+      const nsACString& type, const int64_t& predictedSize,
+      PHttpChannelChild* channel);
+  bool DeallocPAltDataOutputStreamChild(PAltDataOutputStreamChild* aActor);
+
+  PCookieServiceChild* AllocPCookieServiceChild();
+  bool DeallocPCookieServiceChild(PCookieServiceChild*);
+#ifdef MOZ_WIDGET_GTK
+  PGIOChannelChild* AllocPGIOChannelChild(
+      PBrowserChild* aBrowser, const SerializedLoadContext& aSerialized,
+      const GIOChannelCreationArgs& aOpenArgs);
+  bool DeallocPGIOChannelChild(PGIOChannelChild*);
+#endif
+  PWebSocketChild* AllocPWebSocketChild(PBrowserChild*,
+                                        const SerializedLoadContext&,
+                                        const uint32_t&);
+  bool DeallocPWebSocketChild(PWebSocketChild*);
+  PTCPSocketChild* AllocPTCPSocketChild(const nsAString& host,
+                                        const uint16_t& port);
+  bool DeallocPTCPSocketChild(PTCPSocketChild*);
+  PTCPServerSocketChild* AllocPTCPServerSocketChild(
+      const uint16_t& aLocalPort, const uint16_t& aBacklog,
+      const bool& aUseArrayBuffers);
+  bool DeallocPTCPServerSocketChild(PTCPServerSocketChild*);
+  PUDPSocketChild* AllocPUDPSocketChild(nsIPrincipal* aPrincipal,
+                                        const nsACString& aFilter);
+  bool DeallocPUDPSocketChild(PUDPSocketChild*);
+  PSimpleChannelChild* AllocPSimpleChannelChild(const uint32_t& channelId);
+  bool DeallocPSimpleChannelChild(PSimpleChannelChild* child);
+  PTransportProviderChild* AllocPTransportProviderChild();
+  bool DeallocPTransportProviderChild(PTransportProviderChild* aActor);
+  PWebSocketEventListenerChild* AllocPWebSocketEventListenerChild(
+      const uint64_t& aInnerWindowID);
+  bool DeallocPWebSocketEventListenerChild(PWebSocketEventListenerChild*);
+
+  /* Predictor Messsages */
+  mozilla::ipc::IPCResult RecvPredOnPredictPrefetch(
+      nsIURI* aURI, const uint32_t& aHttpStatus);
+  mozilla::ipc::IPCResult RecvPredOnPredictPreconnect(nsIURI* aURI);
+  mozilla::ipc::IPCResult RecvPredOnPredictDNS(nsIURI* aURI);
+
+  mozilla::ipc::IPCResult RecvSpeculativeConnectRequest();
+  mozilla::ipc::IPCResult RecvNetworkChangeNotification(nsCString const& type);
+
+  mozilla::ipc::IPCResult RecvSetTRRDomain(const nsCString& domain);
+};
+
+/**
+ * Reference to the PNecko Child protocol.
+ * Null if this is not a content process.
+ */
+extern PNeckoChild* gNeckoChild;
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_net_NeckoChild_h
diff --git a/netwerk/ipc/NeckoCommon.cpp b/netwerk/ipc/NeckoCommon.cpp
new file mode 100644
index 0000000000..c08faa5747
--- /dev/null
+++ b/netwerk/ipc/NeckoCommon.cpp
@@ -0,0 +1,70 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "NeckoCommon.h"
+
+#include "nsIInputStream.h"
+#include "nsIMultiPartChannel.h"
+#include "nsIParentChannel.h"
+#include "nsStringStream.h"
+
+namespace mozilla::net {
+
+nsresult ForwardStreamListenerFunctions(
+    nsTArray<StreamListenerFunction>& aCalls, nsIStreamListener* aParent) {
+  nsresult rv = NS_OK;
+  for (auto& variant : aCalls) {
+    variant.match(
+        [&](const OnStartRequestParams& aParams) {
+          rv = aParent->OnStartRequest(aParams.request);
+          if (NS_FAILED(rv)) {
+            aParams.request->Cancel(rv);
+          }
+        },
+        [&](const OnDataAvailableParams& aParams) {
+          // Don't deliver OnDataAvailable if we've
+          // already failed.
+          if (NS_FAILED(rv)) {
+            return;
+          }
+          nsCOMPtr<nsIInputStream> stringStream;
+          rv = NS_NewByteInputStream(
+              getter_AddRefs(stringStream),
+              Span<const char>(aParams.data.get(), aParams.count),
+              NS_ASSIGNMENT_DEPEND);
+          if (NS_SUCCEEDED(rv)) {
+            rv = aParent->OnDataAvailable(aParams.request, stringStream,
+                                          aParams.offset, aParams.count);
+          }
+          if (NS_FAILED(rv)) {
+            aParams.request->Cancel(rv);
+          }
+        },
+        [&](const OnStopRequestParams& aParams) {
+          if (NS_SUCCEEDED(rv)) {
+            aParent->OnStopRequest(aParams.request, aParams.status);
+          } else {
+            aParent->OnStopRequest(aParams.request, rv);
+          }
+          rv = NS_OK;
+        },
+        [&](const OnAfterLastPartParams& aParams) {
+          nsCOMPtr<nsIMultiPartChannelListener> multiListener =
+              do_QueryInterface(aParent);
+          if (multiListener) {
+            if (NS_SUCCEEDED(rv)) {
+              multiListener->OnAfterLastPart(aParams.status);
+            } else {
+              multiListener->OnAfterLastPart(rv);
+            }
+          }
+        });
+  }
+  return rv;
+}
+
+}  // namespace mozilla::net
diff --git a/netwerk/ipc/NeckoCommon.h b/netwerk/ipc/NeckoCommon.h
new file mode 100644
index 0000000000..6f63ef1b2a
--- /dev/null
+++ b/netwerk/ipc/NeckoCommon.h
@@ -0,0 +1,144 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_NeckoCommon_h
+#define mozilla_net_NeckoCommon_h
+
+#include "mozilla/Preferences.h"
+#include "mozilla/Variant.h"
+#include "nsIRequest.h"
+#include "nsPrintfCString.h"
+#include "nsXULAppAPI.h"
+#include "prenv.h"
+
+class nsIStreamListener;
+
+namespace mozilla {
+namespace dom {
+class BrowserChild;
+}  // namespace dom
+}  // namespace mozilla
+
+#if defined(DEBUG)
+#  define NECKO_ERRORS_ARE_FATAL_DEFAULT true
+#else
+#  define NECKO_ERRORS_ARE_FATAL_DEFAULT false
+#endif
+
+// TODO: Eventually remove NECKO_MAYBE_ABORT and DROP_DEAD (bug 575494).
+// Still useful for catching listener interfaces we don't yet support across
+// processes, etc.
+
+#define NECKO_MAYBE_ABORT(msg)                                  \
+  do {                                                          \
+    bool abort = NECKO_ERRORS_ARE_FATAL_DEFAULT;                \
+    const char* e = PR_GetEnv("NECKO_ERRORS_ARE_FATAL");        \
+    if (e) abort = (*e == '0') ? false : true;                  \
+    if (abort) {                                                \
+      msg.AppendLiteral(                                        \
+          " (set NECKO_ERRORS_ARE_FATAL=0 in your environment " \
+          "to convert this error into a warning.)");            \
+      MOZ_CRASH_UNSAFE(msg.get());                              \
+    } else {                                                    \
+      msg.AppendLiteral(                                        \
+          " (set NECKO_ERRORS_ARE_FATAL=1 in your environment " \
+          "to convert this warning into a fatal error.)");      \
+      NS_WARNING(msg.get());                                    \
+    }                                                           \
+  } while (0)
+
+#define DROP_DEAD()                                                       \
+  do {                                                                    \
+    nsPrintfCString msg("NECKO ERROR: '%s' UNIMPLEMENTED", __FUNCTION__); \
+    NECKO_MAYBE_ABORT(msg);                                               \
+    return NS_ERROR_NOT_IMPLEMENTED;                                      \
+  } while (0)
+
+#define ENSURE_CALLED_BEFORE_ASYNC_OPEN()                                      \
+  do {                                                                         \
+    if (LoadIsPending() || LoadWasOpened()) {                                  \
+      nsPrintfCString msg("'%s' called after AsyncOpen: %s +%d", __FUNCTION__, \
+                          __FILE__, __LINE__);                                 \
+      NECKO_MAYBE_ABORT(msg);                                                  \
+    }                                                                          \
+    NS_ENSURE_TRUE(!LoadIsPending(), NS_ERROR_IN_PROGRESS);                    \
+    NS_ENSURE_TRUE(!LoadWasOpened(), NS_ERROR_ALREADY_OPENED);                 \
+  } while (0)
+
+// Fails call if made after request observers (on-modify-request, etc) have been
+// called
+
+#define ENSURE_CALLED_BEFORE_CONNECT()                                  \
+  do {                                                                  \
+    if (LoadRequestObserversCalled()) {                                 \
+      nsPrintfCString msg("'%s' called too late: %s +%d", __FUNCTION__, \
+                          __FILE__, __LINE__);                          \
+      NECKO_MAYBE_ABORT(msg);                                           \
+      if (LoadIsPending()) return NS_ERROR_IN_PROGRESS;                 \
+      MOZ_ASSERT(LoadWasOpened());                                      \
+      return NS_ERROR_ALREADY_OPENED;                                   \
+    }                                                                   \
+  } while (0)
+
+namespace mozilla {
+namespace net {
+
+inline bool IsNeckoChild() {
+  static bool didCheck = false;
+  static bool amChild = false;
+
+  if (!didCheck) {
+    didCheck = true;
+    amChild = (XRE_GetProcessType() == GeckoProcessType_Content);
+  }
+  return amChild;
+}
+
+inline bool IsSocketProcessChild() {
+  static bool amChild = (XRE_GetProcessType() == GeckoProcessType_Socket);
+  return amChild;
+}
+
+class HttpChannelSecurityWarningReporter : public nsISupports {
+ public:
+  [[nodiscard]] virtual nsresult ReportSecurityMessage(
+      const nsAString& aMessageTag, const nsAString& aMessageCategory) = 0;
+  [[nodiscard]] virtual nsresult LogBlockedCORSRequest(
+      const nsAString& aMessage, const nsACString& aCategory,
+      bool aIsWarning = false) = 0;
+  [[nodiscard]] virtual nsresult LogMimeTypeMismatch(
+      const nsACString& aMessageName, bool aWarning, const nsAString& aURL,
+      const nsAString& aContentType) = 0;
+};
+
+struct OnStartRequestParams {
+  nsCOMPtr<nsIRequest> request;
+};
+struct OnDataAvailableParams {
+  nsCOMPtr<nsIRequest> request;
+  nsCString data;
+  uint64_t offset;
+  uint32_t count;
+};
+struct OnStopRequestParams {
+  nsCOMPtr<nsIRequest> request;
+  nsresult status;
+};
+struct OnAfterLastPartParams {
+  nsresult status;
+};
+using StreamListenerFunction =
+    mozilla::Variant<OnStartRequestParams, OnDataAvailableParams,
+                     OnStopRequestParams, OnAfterLastPartParams>;
+
+nsresult ForwardStreamListenerFunctions(
+    nsTArray<StreamListenerFunction>& aCalls, nsIStreamListener* aParent);
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_net_NeckoCommon_h
diff --git a/netwerk/ipc/NeckoMessageUtils.h b/netwerk/ipc/NeckoMessageUtils.h
new file mode 100644
index 0000000000..a15398330e
--- /dev/null
+++ b/netwerk/ipc/NeckoMessageUtils.h
@@ -0,0 +1,190 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_NeckoMessageUtils_h
+#define mozilla_net_NeckoMessageUtils_h
+
+#include "mozilla/DebugOnly.h"
+
+#include "ipc/EnumSerializer.h"
+#include "ipc/IPCMessageUtils.h"
+#include "nsExceptionHandler.h"
+#include "nsIHttpChannel.h"
+#include "nsPrintfCString.h"
+#include "nsString.h"
+#include "prio.h"
+#include "mozilla/net/DNS.h"
+#include "ipc/IPCMessageUtilsSpecializations.h"
+#include "nsITRRSkipReason.h"
+#include "nsIDNSService.h"
+
+namespace IPC {
+
+// nsIPermissionManager utilities
+
+struct Permission {
+  nsCString origin, type;
+  uint32_t capability, expireType;
+  int64_t expireTime;
+
+  Permission() : capability(0), expireType(0), expireTime(0) {}
+
+  Permission(const nsCString& aOrigin, const nsACString& aType,
+             const uint32_t aCapability, const uint32_t aExpireType,
+             const int64_t aExpireTime)
+      : origin(aOrigin),
+        type(aType),
+        capability(aCapability),
+        expireType(aExpireType),
+        expireTime(aExpireTime) {}
+
+  bool operator==(const Permission& aOther) const {
+    return aOther.origin == origin && aOther.type == type &&
+           aOther.capability == capability && aOther.expireType == expireType &&
+           aOther.expireTime == expireTime;
+  }
+};
+
+template <>
+struct ParamTraits<Permission> {
+  static void Write(MessageWriter* aWriter, const Permission& aParam) {
+    WriteParam(aWriter, aParam.origin);
+    WriteParam(aWriter, aParam.type);
+    WriteParam(aWriter, aParam.capability);
+    WriteParam(aWriter, aParam.expireType);
+    WriteParam(aWriter, aParam.expireTime);
+  }
+
+  static bool Read(MessageReader* aReader, Permission* aResult) {
+    return ReadParam(aReader, &aResult->origin) &&
+           ReadParam(aReader, &aResult->type) &&
+           ReadParam(aReader, &aResult->capability) &&
+           ReadParam(aReader, &aResult->expireType) &&
+           ReadParam(aReader, &aResult->expireTime);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::net::NetAddr> {
+  static void Write(MessageWriter* aWriter,
+                    const mozilla::net::NetAddr& aParam) {
+    WriteParam(aWriter, aParam.raw.family);
+    if (aParam.raw.family == AF_UNSPEC) {
+      aWriter->WriteBytes(aParam.raw.data, sizeof(aParam.raw.data));
+    } else if (aParam.raw.family == AF_INET) {
+      WriteParam(aWriter, aParam.inet.port);
+      WriteParam(aWriter, aParam.inet.ip);
+    } else if (aParam.raw.family == AF_INET6) {
+      WriteParam(aWriter, aParam.inet6.port);
+      WriteParam(aWriter, aParam.inet6.flowinfo);
+      WriteParam(aWriter, aParam.inet6.ip.u64[0]);
+      WriteParam(aWriter, aParam.inet6.ip.u64[1]);
+      WriteParam(aWriter, aParam.inet6.scope_id);
+#if defined(XP_UNIX)
+    } else if (aParam.raw.family == AF_LOCAL) {
+      // Train's already off the rails:  let's get a stack trace at least...
+      MOZ_CRASH(
+          "Error: please post stack trace to "
+          "https://bugzilla.mozilla.org/show_bug.cgi?id=661158");
+      aWriter->WriteBytes(aParam.local.path, sizeof(aParam.local.path));
+#endif
+    } else {
+      if (XRE_IsParentProcess()) {
+        nsPrintfCString msg("%d", aParam.raw.family);
+        CrashReporter::AnnotateCrashReport(
+            CrashReporter::Annotation::UnknownNetAddrSocketFamily, msg);
+      }
+
+      MOZ_CRASH("Unknown socket family");
+    }
+  }
+
+  static bool Read(MessageReader* aReader, mozilla::net::NetAddr* aResult) {
+    if (!ReadParam(aReader, &aResult->raw.family)) return false;
+
+    if (aResult->raw.family == AF_UNSPEC) {
+      return aReader->ReadBytesInto(&aResult->raw.data,
+                                    sizeof(aResult->raw.data));
+    } else if (aResult->raw.family == AF_INET) {
+      return ReadParam(aReader, &aResult->inet.port) &&
+             ReadParam(aReader, &aResult->inet.ip);
+    } else if (aResult->raw.family == AF_INET6) {
+      return ReadParam(aReader, &aResult->inet6.port) &&
+             ReadParam(aReader, &aResult->inet6.flowinfo) &&
+             ReadParam(aReader, &aResult->inet6.ip.u64[0]) &&
+             ReadParam(aReader, &aResult->inet6.ip.u64[1]) &&
+             ReadParam(aReader, &aResult->inet6.scope_id);
+#if defined(XP_UNIX)
+    } else if (aResult->raw.family == AF_LOCAL) {
+      return aReader->ReadBytesInto(&aResult->local.path,
+                                    sizeof(aResult->local.path));
+#endif
+    }
+
+    /* We've been tricked by some socket family we don't know about! */
+    return false;
+  }
+};
+
+template <>
+struct ParamTraits<nsIRequest::TRRMode> {
+  static void Write(MessageWriter* aWriter, const nsIRequest::TRRMode& aParam) {
+    WriteParam(aWriter, (uint8_t)aParam);
+  }
+  static bool Read(MessageReader* aReader, nsIRequest::TRRMode* aResult) {
+    uint8_t mode;
+    if (!ReadParam(aReader, &mode)) {
+      return false;
+    }
+    // TODO: sanity check
+    *aResult = static_cast<nsIRequest::TRRMode>(mode);
+    return true;
+  }
+};
+
+template <>
+struct ParamTraits<nsITRRSkipReason::value> {
+  static void Write(MessageWriter* aWriter,
+                    const nsITRRSkipReason::value& aParam) {
+    WriteParam(aWriter, (uint8_t)aParam);
+  }
+  static bool Read(MessageReader* aReader, nsITRRSkipReason::value* aResult) {
+    uint8_t reason;
+    if (!ReadParam(aReader, &reason)) {
+      return false;
+    }
+    // TODO: sanity check
+    *aResult = static_cast<nsITRRSkipReason::value>(reason);
+    return true;
+  }
+};
+
+template <>
+struct ParamTraits<nsIDNSService::DNSFlags>
+    : public BitFlagsEnumSerializer<
+          nsIDNSService::DNSFlags, nsIDNSService::DNSFlags::ALL_DNSFLAGS_BITS> {
+};
+
+template <>
+struct ParamTraits<nsIDNSService::ResolverMode> {
+  static void Write(MessageWriter* aWriter,
+                    const nsIDNSService::ResolverMode& aParam) {
+    WriteParam(aWriter, (uint8_t)aParam);
+  }
+  static bool Read(MessageReader* aReader,
+                   nsIDNSService::ResolverMode* aResult) {
+    uint8_t mode;
+    if (!ReadParam(aReader, &mode)) {
+      return false;
+    }
+    // TODO: sanity check
+    *aResult = static_cast<nsIDNSService::ResolverMode>(mode);
+    return true;
+  }
+};
+
+}  // namespace IPC
+
+#endif  // mozilla_net_NeckoMessageUtils_h
diff --git a/netwerk/ipc/NeckoParent.cpp b/netwerk/ipc/NeckoParent.cpp
new file mode 100644
index 0000000000..06d6781c57
--- /dev/null
+++ b/netwerk/ipc/NeckoParent.cpp
@@ -0,0 +1,898 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsHttp.h"
+#include "mozilla/BasePrincipal.h"
+#include "mozilla/ContentPrincipal.h"
+#include "mozilla/ipc/IPCStreamUtils.h"
+#include "mozilla/net/ExtensionProtocolHandler.h"
+#include "mozilla/net/PageThumbProtocolHandler.h"
+#include "mozilla/net/NeckoParent.h"
+#include "mozilla/net/HttpChannelParent.h"
+#include "mozilla/net/CookieServiceParent.h"
+#include "mozilla/net/WebSocketChannelParent.h"
+#include "mozilla/net/WebSocketEventListenerParent.h"
+#include "mozilla/net/DataChannelParent.h"
+#ifdef MOZ_WIDGET_GTK
+#  include "mozilla/net/GIOChannelParent.h"
+#endif
+#include "mozilla/net/DocumentChannelParent.h"
+#include "mozilla/net/SimpleChannelParent.h"
+#include "mozilla/net/AltDataOutputStreamParent.h"
+#include "mozilla/Unused.h"
+#include "mozilla/net/FileChannelParent.h"
+#include "mozilla/net/DNSRequestParent.h"
+#include "mozilla/net/IPCTransportProvider.h"
+#include "mozilla/net/RemoteStreamGetter.h"
+#include "mozilla/net/RequestContextService.h"
+#include "mozilla/net/SocketProcessParent.h"
+#include "mozilla/net/PSocketProcessBridgeParent.h"
+#ifdef MOZ_WEBRTC
+#  include "mozilla/net/StunAddrsRequestParent.h"
+#  include "mozilla/net/WebrtcTCPSocketParent.h"
+#endif
+#include "mozilla/dom/ContentParent.h"
+#include "mozilla/dom/BrowserParent.h"
+#include "mozilla/dom/MaybeDiscarded.h"
+#include "mozilla/dom/network/TCPSocketParent.h"
+#include "mozilla/dom/network/TCPServerSocketParent.h"
+#include "mozilla/dom/network/UDPSocketParent.h"
+#ifdef MOZ_PLACES
+#  include "mozilla/places/PageIconProtocolHandler.h"
+#endif
+#include "mozilla/LoadContext.h"
+#include "mozilla/MozPromise.h"
+#include "nsPrintfCString.h"
+#include "mozilla/dom/HTMLDNSPrefetch.h"
+#include "nsEscape.h"
+#include "SerializedLoadContext.h"
+#include "nsAuthInformationHolder.h"
+#include "nsINetworkPredictor.h"
+#include "nsINetworkPredictorVerifier.h"
+#include "nsISpeculativeConnect.h"
+#include "nsHttpHandler.h"
+#include "nsNetUtil.h"
+#include "nsIOService.h"
+
+using IPC::SerializedLoadContext;
+using mozilla::dom::BrowserParent;
+using mozilla::dom::ContentParent;
+using mozilla::dom::TCPServerSocketParent;
+using mozilla::dom::TCPSocketParent;
+using mozilla::dom::UDPSocketParent;
+using mozilla::ipc::LoadInfoArgsToLoadInfo;
+using mozilla::ipc::PrincipalInfo;
+#ifdef MOZ_PLACES
+using mozilla::places::PageIconProtocolHandler;
+#endif
+
+namespace mozilla {
+namespace net {
+
+// C++ file contents
+NeckoParent::NeckoParent() : mSocketProcessBridgeInited(false) {
+  // Init HTTP protocol handler now since we need atomTable up and running very
+  // early (IPDL argument handling for PHttpChannel constructor needs it) so
+  // normal init (during 1st Http channel request) isn't early enough.
+  nsCOMPtr<nsIProtocolHandler> proto =
+      do_GetService("@mozilla.org/network/protocol;1?name=http");
+}
+
+static PBOverrideStatus PBOverrideStatusFromLoadContext(
+    const SerializedLoadContext& aSerialized) {
+  if (!aSerialized.IsNotNull() && aSerialized.IsPrivateBitValid()) {
+    return (aSerialized.mOriginAttributes.mPrivateBrowsingId > 0)
+               ? kPBOverride_Private
+               : kPBOverride_NotPrivate;
+  }
+  return kPBOverride_Unset;
+}
+
+static already_AddRefed<nsIPrincipal> GetRequestingPrincipal(
+    const Maybe<LoadInfoArgs>& aOptionalLoadInfoArgs) {
+  if (aOptionalLoadInfoArgs.isNothing()) {
+    return nullptr;
+  }
+
+  const LoadInfoArgs& loadInfoArgs = aOptionalLoadInfoArgs.ref();
+  const Maybe<PrincipalInfo>& optionalPrincipalInfo =
+      loadInfoArgs.requestingPrincipalInfo();
+
+  if (optionalPrincipalInfo.isNothing()) {
+    return nullptr;
+  }
+
+  const PrincipalInfo& principalInfo = optionalPrincipalInfo.ref();
+
+  auto principalOrErr = PrincipalInfoToPrincipal(principalInfo);
+  return principalOrErr.isOk() ? principalOrErr.unwrap().forget() : nullptr;
+}
+
+static already_AddRefed<nsIPrincipal> GetRequestingPrincipal(
+    const HttpChannelCreationArgs& aArgs) {
+  if (aArgs.type() != HttpChannelCreationArgs::THttpChannelOpenArgs) {
+    return nullptr;
+  }
+
+  const HttpChannelOpenArgs& args = aArgs.get_HttpChannelOpenArgs();
+  return GetRequestingPrincipal(args.loadInfo());
+}
+
+const char* NeckoParent::GetValidatedOriginAttributes(
+    const SerializedLoadContext& aSerialized, PContentParent* aContent,
+    nsIPrincipal* aRequestingPrincipal, OriginAttributes& aAttrs) {
+  if (!aSerialized.IsNotNull()) {
+    // If serialized is null, we cannot validate anything. We have to assume
+    // that this requests comes from a SystemPrincipal.
+    aAttrs = OriginAttributes(false);
+  } else {
+    aAttrs = aSerialized.mOriginAttributes;
+  }
+  return nullptr;
+}
+
+const char* NeckoParent::CreateChannelLoadContext(
+    PBrowserParent* aBrowser, PContentParent* aContent,
+    const SerializedLoadContext& aSerialized,
+    nsIPrincipal* aRequestingPrincipal, nsCOMPtr<nsILoadContext>& aResult) {
+  OriginAttributes attrs;
+  const char* error = GetValidatedOriginAttributes(aSerialized, aContent,
+                                                   aRequestingPrincipal, attrs);
+  if (error) {
+    return error;
+  }
+
+  // if !UsingNeckoIPCSecurity(), we may not have a LoadContext to set. This is
+  // the common case for most xpcshell tests.
+  if (aSerialized.IsNotNull()) {
+    attrs.SyncAttributesWithPrivateBrowsing(
+        aSerialized.mOriginAttributes.mPrivateBrowsingId > 0);
+
+    RefPtr<BrowserParent> browserParent = BrowserParent::GetFrom(aBrowser);
+    dom::Element* topFrameElement = nullptr;
+    if (browserParent) {
+      topFrameElement = browserParent->GetOwnerElement();
+    }
+    aResult = new LoadContext(aSerialized, topFrameElement, attrs);
+  }
+
+  return nullptr;
+}
+
+void NeckoParent::ActorDestroy(ActorDestroyReason aWhy) {
+  // Nothing needed here. Called right before destructor since this is a
+  // non-refcounted class.
+}
+
+already_AddRefed<PHttpChannelParent> NeckoParent::AllocPHttpChannelParent(
+    PBrowserParent* aBrowser, const SerializedLoadContext& aSerialized,
+    const HttpChannelCreationArgs& aOpenArgs) {
+  nsCOMPtr<nsIPrincipal> requestingPrincipal =
+      GetRequestingPrincipal(aOpenArgs);
+
+  nsCOMPtr<nsILoadContext> loadContext;
+  const char* error = CreateChannelLoadContext(
+      aBrowser, Manager(), aSerialized, requestingPrincipal, loadContext);
+  if (error) {
+    printf_stderr(
+        "NeckoParent::AllocPHttpChannelParent: "
+        "FATAL error: %s: KILLING CHILD PROCESS\n",
+        error);
+    return nullptr;
+  }
+  PBOverrideStatus overrideStatus =
+      PBOverrideStatusFromLoadContext(aSerialized);
+  RefPtr<HttpChannelParent> p = new HttpChannelParent(
+      BrowserParent::GetFrom(aBrowser), loadContext, overrideStatus);
+  return p.forget();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvPHttpChannelConstructor(
+    PHttpChannelParent* aActor, PBrowserParent* aBrowser,
+    const SerializedLoadContext& aSerialized,
+    const HttpChannelCreationArgs& aOpenArgs) {
+  HttpChannelParent* p = static_cast<HttpChannelParent*>(aActor);
+  if (!p->Init(aOpenArgs)) {
+    return IPC_FAIL_NO_REASON(this);
+  }
+  return IPC_OK();
+}
+
+PStunAddrsRequestParent* NeckoParent::AllocPStunAddrsRequestParent() {
+#ifdef MOZ_WEBRTC
+  StunAddrsRequestParent* p = new StunAddrsRequestParent();
+  p->AddRef();
+  return p;
+#else
+  return nullptr;
+#endif
+}
+
+bool NeckoParent::DeallocPStunAddrsRequestParent(
+    PStunAddrsRequestParent* aActor) {
+#ifdef MOZ_WEBRTC
+  StunAddrsRequestParent* p = static_cast<StunAddrsRequestParent*>(aActor);
+  p->Release();
+#endif
+  return true;
+}
+
+PWebrtcTCPSocketParent* NeckoParent::AllocPWebrtcTCPSocketParent(
+    const Maybe<TabId>& aTabId) {
+#ifdef MOZ_WEBRTC
+  WebrtcTCPSocketParent* parent = new WebrtcTCPSocketParent(aTabId);
+  parent->AddRef();
+  return parent;
+#else
+  return nullptr;
+#endif
+}
+
+bool NeckoParent::DeallocPWebrtcTCPSocketParent(
+    PWebrtcTCPSocketParent* aActor) {
+#ifdef MOZ_WEBRTC
+  WebrtcTCPSocketParent* parent = static_cast<WebrtcTCPSocketParent*>(aActor);
+  parent->Release();
+#endif
+  return true;
+}
+
+PAltDataOutputStreamParent* NeckoParent::AllocPAltDataOutputStreamParent(
+    const nsACString& type, const int64_t& predictedSize,
+    PHttpChannelParent* channel) {
+  HttpChannelParent* chan = static_cast<HttpChannelParent*>(channel);
+  nsCOMPtr<nsIAsyncOutputStream> stream;
+  nsresult rv = chan->OpenAlternativeOutputStream(type, predictedSize,
+                                                  getter_AddRefs(stream));
+  AltDataOutputStreamParent* parent = new AltDataOutputStreamParent(stream);
+  parent->AddRef();
+  // If the return value was not NS_OK, the error code will be sent
+  // asynchronously to the child, after receiving the first message.
+  parent->SetError(rv);
+  return parent;
+}
+
+bool NeckoParent::DeallocPAltDataOutputStreamParent(
+    PAltDataOutputStreamParent* aActor) {
+  AltDataOutputStreamParent* parent =
+      static_cast<AltDataOutputStreamParent*>(aActor);
+  parent->Release();
+  return true;
+}
+
+already_AddRefed<PDocumentChannelParent>
+NeckoParent::AllocPDocumentChannelParent(
+    const dom::MaybeDiscarded<dom::BrowsingContext>& aContext,
+    const DocumentChannelCreationArgs& args) {
+  RefPtr<DocumentChannelParent> p = new DocumentChannelParent();
+  return p.forget();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvPDocumentChannelConstructor(
+    PDocumentChannelParent* aActor,
+    const dom::MaybeDiscarded<dom::BrowsingContext>& aContext,
+    const DocumentChannelCreationArgs& aArgs) {
+  DocumentChannelParent* p = static_cast<DocumentChannelParent*>(aActor);
+
+  if (aContext.IsNullOrDiscarded()) {
+    Unused << p->SendFailedAsyncOpen(NS_ERROR_FAILURE);
+    return IPC_OK();
+  }
+
+  if (!p->Init(aContext.get_canonical(), aArgs)) {
+    return IPC_FAIL(this, "Couldn't initialize DocumentChannel");
+  }
+
+  return IPC_OK();
+}
+
+PCookieServiceParent* NeckoParent::AllocPCookieServiceParent() {
+  return new CookieServiceParent();
+}
+
+bool NeckoParent::DeallocPCookieServiceParent(PCookieServiceParent* cs) {
+  delete cs;
+  return true;
+}
+
+PWebSocketParent* NeckoParent::AllocPWebSocketParent(
+    PBrowserParent* browser, const SerializedLoadContext& serialized,
+    const uint32_t& aSerial) {
+  nsCOMPtr<nsILoadContext> loadContext;
+  const char* error = CreateChannelLoadContext(browser, Manager(), serialized,
+                                               nullptr, loadContext);
+  if (error) {
+    printf_stderr(
+        "NeckoParent::AllocPWebSocketParent: "
+        "FATAL error: %s: KILLING CHILD PROCESS\n",
+        error);
+    return nullptr;
+  }
+
+  RefPtr<BrowserParent> browserParent = BrowserParent::GetFrom(browser);
+  PBOverrideStatus overrideStatus = PBOverrideStatusFromLoadContext(serialized);
+  WebSocketChannelParent* p = new WebSocketChannelParent(
+      browserParent, loadContext, overrideStatus, aSerial);
+  p->AddRef();
+  return p;
+}
+
+bool NeckoParent::DeallocPWebSocketParent(PWebSocketParent* actor) {
+  WebSocketChannelParent* p = static_cast<WebSocketChannelParent*>(actor);
+  p->Release();
+  return true;
+}
+
+PWebSocketEventListenerParent* NeckoParent::AllocPWebSocketEventListenerParent(
+    const uint64_t& aInnerWindowID) {
+  RefPtr<WebSocketEventListenerParent> c =
+      new WebSocketEventListenerParent(aInnerWindowID);
+  return c.forget().take();
+}
+
+bool NeckoParent::DeallocPWebSocketEventListenerParent(
+    PWebSocketEventListenerParent* aActor) {
+  RefPtr<WebSocketEventListenerParent> c =
+      dont_AddRef(static_cast<WebSocketEventListenerParent*>(aActor));
+  MOZ_ASSERT(c);
+  return true;
+}
+
+already_AddRefed<PDataChannelParent> NeckoParent::AllocPDataChannelParent(
+    const uint32_t& channelId) {
+  RefPtr<DataChannelParent> p = new DataChannelParent();
+  return p.forget();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvPDataChannelConstructor(
+    PDataChannelParent* actor, const uint32_t& channelId) {
+  DataChannelParent* p = static_cast<DataChannelParent*>(actor);
+  DebugOnly<bool> rv = p->Init(channelId);
+  MOZ_ASSERT(rv);
+  return IPC_OK();
+}
+
+#ifdef MOZ_WIDGET_GTK
+static already_AddRefed<nsIPrincipal> GetRequestingPrincipal(
+    const GIOChannelCreationArgs& aArgs) {
+  if (aArgs.type() != GIOChannelCreationArgs::TGIOChannelOpenArgs) {
+    return nullptr;
+  }
+
+  const GIOChannelOpenArgs& args = aArgs.get_GIOChannelOpenArgs();
+  return GetRequestingPrincipal(args.loadInfo());
+}
+
+PGIOChannelParent* NeckoParent::AllocPGIOChannelParent(
+    PBrowserParent* aBrowser, const SerializedLoadContext& aSerialized,
+    const GIOChannelCreationArgs& aOpenArgs) {
+  nsCOMPtr<nsIPrincipal> requestingPrincipal =
+      GetRequestingPrincipal(aOpenArgs);
+
+  nsCOMPtr<nsILoadContext> loadContext;
+  const char* error = CreateChannelLoadContext(
+      aBrowser, Manager(), aSerialized, requestingPrincipal, loadContext);
+  if (error) {
+    printf_stderr(
+        "NeckoParent::AllocPGIOChannelParent: "
+        "FATAL error: %s: KILLING CHILD PROCESS\n",
+        error);
+    return nullptr;
+  }
+  PBOverrideStatus overrideStatus =
+      PBOverrideStatusFromLoadContext(aSerialized);
+  GIOChannelParent* p = new GIOChannelParent(BrowserParent::GetFrom(aBrowser),
+                                             loadContext, overrideStatus);
+  p->AddRef();
+  return p;
+}
+
+bool NeckoParent::DeallocPGIOChannelParent(PGIOChannelParent* channel) {
+  GIOChannelParent* p = static_cast<GIOChannelParent*>(channel);
+  p->Release();
+  return true;
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvPGIOChannelConstructor(
+    PGIOChannelParent* actor, PBrowserParent* aBrowser,
+    const SerializedLoadContext& aSerialized,
+    const GIOChannelCreationArgs& aOpenArgs) {
+  GIOChannelParent* p = static_cast<GIOChannelParent*>(actor);
+  DebugOnly<bool> rv = p->Init(aOpenArgs);
+  MOZ_ASSERT(rv);
+  return IPC_OK();
+}
+#endif
+
+PSimpleChannelParent* NeckoParent::AllocPSimpleChannelParent(
+    const uint32_t& channelId) {
+  RefPtr<SimpleChannelParent> p = new SimpleChannelParent();
+  return p.forget().take();
+}
+
+bool NeckoParent::DeallocPSimpleChannelParent(PSimpleChannelParent* actor) {
+  RefPtr<SimpleChannelParent> p =
+      dont_AddRef(actor).downcast<SimpleChannelParent>();
+  return true;
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvPSimpleChannelConstructor(
+    PSimpleChannelParent* actor, const uint32_t& channelId) {
+  SimpleChannelParent* p = static_cast<SimpleChannelParent*>(actor);
+  MOZ_ALWAYS_TRUE(p->Init(channelId));
+  return IPC_OK();
+}
+
+already_AddRefed<PFileChannelParent> NeckoParent::AllocPFileChannelParent(
+    const uint32_t& channelId) {
+  RefPtr<FileChannelParent> p = new FileChannelParent();
+  return p.forget();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvPFileChannelConstructor(
+    PFileChannelParent* actor, const uint32_t& channelId) {
+  FileChannelParent* p = static_cast<FileChannelParent*>(actor);
+  DebugOnly<bool> rv = p->Init(channelId);
+  MOZ_ASSERT(rv);
+  return IPC_OK();
+}
+
+PTCPSocketParent* NeckoParent::AllocPTCPSocketParent(
+    const nsAString& /* host */, const uint16_t& /* port */) {
+  // We actually don't need host/port to construct a TCPSocketParent since
+  // TCPSocketParent will maintain an internal nsIDOMTCPSocket instance which
+  // can be delegated to get the host/port.
+  TCPSocketParent* p = new TCPSocketParent();
+  p->AddIPDLReference();
+  return p;
+}
+
+bool NeckoParent::DeallocPTCPSocketParent(PTCPSocketParent* actor) {
+  TCPSocketParent* p = static_cast<TCPSocketParent*>(actor);
+  p->ReleaseIPDLReference();
+  return true;
+}
+
+PTCPServerSocketParent* NeckoParent::AllocPTCPServerSocketParent(
+    const uint16_t& aLocalPort, const uint16_t& aBacklog,
+    const bool& aUseArrayBuffers) {
+  TCPServerSocketParent* p =
+      new TCPServerSocketParent(this, aLocalPort, aBacklog, aUseArrayBuffers);
+  p->AddIPDLReference();
+  return p;
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvPTCPServerSocketConstructor(
+    PTCPServerSocketParent* aActor, const uint16_t& aLocalPort,
+    const uint16_t& aBacklog, const bool& aUseArrayBuffers) {
+  static_cast<TCPServerSocketParent*>(aActor)->Init();
+  return IPC_OK();
+}
+
+bool NeckoParent::DeallocPTCPServerSocketParent(PTCPServerSocketParent* actor) {
+  TCPServerSocketParent* p = static_cast<TCPServerSocketParent*>(actor);
+  p->ReleaseIPDLReference();
+  return true;
+}
+
+PUDPSocketParent* NeckoParent::AllocPUDPSocketParent(
+    nsIPrincipal* /* unused */, const nsACString& /* unused */) {
+  RefPtr<UDPSocketParent> p = new UDPSocketParent(this);
+
+  return p.forget().take();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvPUDPSocketConstructor(
+    PUDPSocketParent* aActor, nsIPrincipal* aPrincipal,
+    const nsACString& aFilter) {
+  if (!static_cast<UDPSocketParent*>(aActor)->Init(aPrincipal, aFilter)) {
+    return IPC_FAIL_NO_REASON(this);
+  }
+  return IPC_OK();
+}
+
+bool NeckoParent::DeallocPUDPSocketParent(PUDPSocketParent* actor) {
+  UDPSocketParent* p = static_cast<UDPSocketParent*>(actor);
+  p->Release();
+  return true;
+}
+
+already_AddRefed<PDNSRequestParent> NeckoParent::AllocPDNSRequestParent(
+    const nsACString& aHost, const nsACString& aTrrServer, const int32_t& aPort,
+    const uint16_t& aType, const OriginAttributes& aOriginAttributes,
+    const nsIDNSService::DNSFlags& aFlags) {
+  RefPtr<DNSRequestHandler> handler = new DNSRequestHandler();
+  RefPtr<DNSRequestParent> actor = new DNSRequestParent(handler);
+  return actor.forget();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvPDNSRequestConstructor(
+    PDNSRequestParent* aActor, const nsACString& aHost,
+    const nsACString& aTrrServer, const int32_t& aPort, const uint16_t& aType,
+    const OriginAttributes& aOriginAttributes,
+    const nsIDNSService::DNSFlags& aFlags) {
+  RefPtr<DNSRequestParent> actor = static_cast<DNSRequestParent*>(aActor);
+  RefPtr<DNSRequestHandler> handler =
+      actor->GetDNSRequest()->AsDNSRequestHandler();
+  handler->DoAsyncResolve(aHost, aTrrServer, aPort, aType, aOriginAttributes,
+                          aFlags);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvSpeculativeConnect(
+    nsIURI* aURI, nsIPrincipal* aPrincipal,
+    Maybe<OriginAttributes>&& aOriginAttributes, const bool& aAnonymous) {
+  nsCOMPtr<nsISpeculativeConnect> speculator(gIOService);
+  nsCOMPtr<nsIPrincipal> principal(aPrincipal);
+  if (!aURI) {
+    return IPC_FAIL(this, "aURI must not be null");
+  }
+  if (aURI && speculator) {
+    if (aOriginAttributes) {
+      speculator->SpeculativeConnectWithOriginAttributesNative(
+          aURI, std::move(aOriginAttributes.ref()), nullptr, aAnonymous);
+    } else {
+      speculator->SpeculativeConnect(aURI, principal, nullptr, aAnonymous);
+    }
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvHTMLDNSPrefetch(
+    const nsAString& hostname, const bool& isHttps,
+    const OriginAttributes& aOriginAttributes,
+    const nsIDNSService::DNSFlags& flags) {
+  dom::HTMLDNSPrefetch::Prefetch(hostname, isHttps, aOriginAttributes, flags);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvCancelHTMLDNSPrefetch(
+    const nsAString& hostname, const bool& isHttps,
+    const OriginAttributes& aOriginAttributes,
+    const nsIDNSService::DNSFlags& flags, const nsresult& reason) {
+  dom::HTMLDNSPrefetch::CancelPrefetch(hostname, isHttps, aOriginAttributes,
+                                       flags, reason);
+  return IPC_OK();
+}
+
+PTransportProviderParent* NeckoParent::AllocPTransportProviderParent() {
+  RefPtr<TransportProviderParent> res = new TransportProviderParent();
+  return res.forget().take();
+}
+
+bool NeckoParent::DeallocPTransportProviderParent(
+    PTransportProviderParent* aActor) {
+  RefPtr<TransportProviderParent> provider =
+      dont_AddRef(static_cast<TransportProviderParent*>(aActor));
+  return true;
+}
+
+/* Predictor Messages */
+mozilla::ipc::IPCResult NeckoParent::RecvPredPredict(
+    nsIURI* aTargetURI, nsIURI* aSourceURI, const uint32_t& aReason,
+    const OriginAttributes& aOriginAttributes, const bool& hasVerifier) {
+  // Get the current predictor
+  nsresult rv = NS_OK;
+  nsCOMPtr<nsINetworkPredictor> predictor =
+      do_GetService("@mozilla.org/network/predictor;1", &rv);
+  NS_ENSURE_SUCCESS(rv, IPC_OK());
+
+  nsCOMPtr<nsINetworkPredictorVerifier> verifier;
+  if (hasVerifier) {
+    verifier = do_QueryInterface(predictor);
+  }
+  predictor->PredictNative(aTargetURI, aSourceURI, aReason, aOriginAttributes,
+                           verifier);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvPredLearn(
+    nsIURI* aTargetURI, nsIURI* aSourceURI, const uint32_t& aReason,
+    const OriginAttributes& aOriginAttributes) {
+  // Get the current predictor
+  nsresult rv = NS_OK;
+  nsCOMPtr<nsINetworkPredictor> predictor =
+      do_GetService("@mozilla.org/network/predictor;1", &rv);
+  NS_ENSURE_SUCCESS(rv, IPC_OK());
+
+  predictor->LearnNative(aTargetURI, aSourceURI, aReason, aOriginAttributes);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvPredReset() {
+  // Get the current predictor
+  nsresult rv = NS_OK;
+  nsCOMPtr<nsINetworkPredictor> predictor =
+      do_GetService("@mozilla.org/network/predictor;1", &rv);
+  NS_ENSURE_SUCCESS(rv, IPC_OK());
+
+  predictor->Reset();
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvRequestContextLoadBegin(
+    const uint64_t& rcid) {
+  nsCOMPtr<nsIRequestContextService> rcsvc =
+      RequestContextService::GetOrCreate();
+  if (!rcsvc) {
+    return IPC_OK();
+  }
+  nsCOMPtr<nsIRequestContext> rc;
+  rcsvc->GetRequestContext(rcid, getter_AddRefs(rc));
+  if (rc) {
+    rc->BeginLoad();
+  }
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvRequestContextAfterDOMContentLoaded(
+    const uint64_t& rcid) {
+  nsCOMPtr<nsIRequestContextService> rcsvc =
+      RequestContextService::GetOrCreate();
+  if (!rcsvc) {
+    return IPC_OK();
+  }
+  nsCOMPtr<nsIRequestContext> rc;
+  rcsvc->GetRequestContext(rcid, getter_AddRefs(rc));
+  if (rc) {
+    rc->DOMContentLoaded();
+  }
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvRemoveRequestContext(
+    const uint64_t& rcid) {
+  nsCOMPtr<nsIRequestContextService> rcsvc =
+      RequestContextService::GetOrCreate();
+  if (!rcsvc) {
+    return IPC_OK();
+  }
+
+  rcsvc->RemoveRequestContext(rcid);
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvGetExtensionStream(
+    nsIURI* aURI, GetExtensionStreamResolver&& aResolve) {
+  if (!aURI) {
+    return IPC_FAIL(this, "aURI must not be null");
+  }
+
+  RefPtr<ExtensionProtocolHandler> ph(ExtensionProtocolHandler::GetSingleton());
+  MOZ_ASSERT(ph);
+
+  // Ask the ExtensionProtocolHandler to give us a new input stream for
+  // this URI. The request comes from an ExtensionProtocolHandler in the
+  // child process, but is not guaranteed to be a valid moz-extension URI,
+  // and not guaranteed to represent a resource that the child should be
+  // allowed to access. The ExtensionProtocolHandler is responsible for
+  // validating the request. Specifically, only URI's for local files that
+  // an extension is allowed to access via moz-extension URI's should be
+  // accepted.
+  nsCOMPtr<nsIInputStream> inputStream;
+  bool terminateSender = true;
+  auto inputStreamOrReason = ph->NewStream(aURI, &terminateSender);
+  if (inputStreamOrReason.isOk()) {
+    inputStream = inputStreamOrReason.unwrap();
+  }
+
+  // If NewStream failed, we send back an invalid stream to the child so
+  // it can handle the error. MozPromise rejection is reserved for channel
+  // errors/disconnects.
+  aResolve(inputStream);
+
+  if (terminateSender) {
+    return IPC_FAIL_NO_REASON(this);
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvGetExtensionFD(
+    nsIURI* aURI, GetExtensionFDResolver&& aResolve) {
+  if (!aURI) {
+    return IPC_FAIL(this, "aURI must not be null");
+  }
+
+  RefPtr<ExtensionProtocolHandler> ph(ExtensionProtocolHandler::GetSingleton());
+  MOZ_ASSERT(ph);
+
+  // Ask the ExtensionProtocolHandler to give us a new input stream for
+  // this URI. The request comes from an ExtensionProtocolHandler in the
+  // child process, but is not guaranteed to be a valid moz-extension URI,
+  // and not guaranteed to represent a resource that the child should be
+  // allowed to access. The ExtensionProtocolHandler is responsible for
+  // validating the request. Specifically, only URI's for local files that
+  // an extension is allowed to access via moz-extension URI's should be
+  // accepted.
+  bool terminateSender = true;
+  auto result = ph->NewFD(aURI, &terminateSender, aResolve);
+
+  if (result.isErr() && terminateSender) {
+    return IPC_FAIL_NO_REASON(this);
+  }
+
+  if (result.isErr()) {
+    FileDescriptor invalidFD;
+    aResolve(invalidFD);
+  }
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvInitSocketProcessBridge(
+    InitSocketProcessBridgeResolver&& aResolver) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // Initing the socket process bridge must be async here in order to
+  // wait for the socket process launch before executing.
+  auto task = [self = RefPtr{this}, resolver = std::move(aResolver)]() {
+    // The content process might be already destroyed.
+    if (!self->CanSend()) {
+      return;
+    }
+
+    Endpoint<PSocketProcessBridgeChild> invalidEndpoint;
+    if (NS_WARN_IF(self->mSocketProcessBridgeInited)) {
+      resolver(std::move(invalidEndpoint));
+      return;
+    }
+
+    SocketProcessParent* parent = SocketProcessParent::GetSingleton();
+    if (NS_WARN_IF(!parent)) {
+      resolver(std::move(invalidEndpoint));
+      return;
+    }
+
+    Endpoint<PSocketProcessBridgeParent> parentEndpoint;
+    Endpoint<PSocketProcessBridgeChild> childEndpoint;
+    if (NS_WARN_IF(NS_FAILED(PSocketProcessBridge::CreateEndpoints(
+            parent->OtherPid(), self->Manager()->OtherPid(), &parentEndpoint,
+            &childEndpoint)))) {
+      resolver(std::move(invalidEndpoint));
+      return;
+    }
+
+    if (NS_WARN_IF(!parent->SendInitSocketProcessBridgeParent(
+            self->Manager()->OtherPid(), std::move(parentEndpoint)))) {
+      resolver(std::move(invalidEndpoint));
+      return;
+    }
+
+    resolver(std::move(childEndpoint));
+    self->mSocketProcessBridgeInited = true;
+  };
+  gIOService->CallOrWaitForSocketProcess(std::move(task));
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvResetSocketProcessBridge() {
+  // SendResetSocketProcessBridge is called from
+  // SocketProcessBridgeChild::ActorDestroy if the socket process
+  // crashes.  This is necessary in order to properly initialize the
+  // restarted socket process.
+  mSocketProcessBridgeInited = false;
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvEnsureHSTSData(
+    EnsureHSTSDataResolver&& aResolver) {
+  auto callback = [aResolver{std::move(aResolver)}](bool aResult) {
+    aResolver(aResult);
+  };
+  RefPtr<HSTSDataCallbackWrapper> wrapper =
+      new HSTSDataCallbackWrapper(std::move(callback));
+  gHttpHandler->EnsureHSTSDataReadyNative(wrapper);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvGetPageThumbStream(
+    nsIURI* aURI, const Maybe<LoadInfoArgs>& aLoadInfoArgs,
+    GetPageThumbStreamResolver&& aResolver) {
+  // Only the privileged about content process is allowed to access
+  // things over the moz-page-thumb protocol. Any other content process
+  // that tries to send this should have been blocked via the
+  // ScriptSecurityManager, but if somehow the process has been tricked into
+  // sending this message, we send IPC_FAIL in order to crash that
+  // likely-compromised content process.
+  if (static_cast<ContentParent*>(Manager())->GetRemoteType() !=
+      PRIVILEGEDABOUT_REMOTE_TYPE) {
+    return IPC_FAIL(this, "Wrong process type");
+  }
+
+  RefPtr<PageThumbProtocolHandler> ph(PageThumbProtocolHandler::GetSingleton());
+  MOZ_ASSERT(ph);
+
+  // Ask the PageThumbProtocolHandler to give us a new input stream for
+  // this URI. The request comes from a PageThumbProtocolHandler in the
+  // child process, but is not guaranteed to be a valid moz-page-thumb URI,
+  // and not guaranteed to represent a resource that the child should be
+  // allowed to access. The PageThumbProtocolHandler is responsible for
+  // validating the request.
+  nsCOMPtr<nsIInputStream> inputStream;
+  bool terminateSender = true;
+  auto inputStreamPromise = ph->NewStream(aURI, &terminateSender);
+
+  if (terminateSender) {
+    return IPC_FAIL(this, "Malformed moz-page-thumb request");
+  }
+
+  inputStreamPromise->Then(
+      GetMainThreadSerialEventTarget(), __func__,
+      [aResolver](const RemoteStreamInfo& aInfo) { aResolver(Some(aInfo)); },
+      [aResolver](nsresult aRv) {
+        // If NewStream failed, we send back an invalid stream to the child so
+        // it can handle the error. MozPromise rejection is reserved for channel
+        // errors/disconnects.
+        Unused << NS_WARN_IF(NS_FAILED(aRv));
+        aResolver(Nothing());
+      });
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult NeckoParent::RecvGetPageIconStream(
+    nsIURI* aURI, const Maybe<LoadInfoArgs>& aLoadInfoArgs,
+    GetPageIconStreamResolver&& aResolver) {
+#ifdef MOZ_PLACES
+  const nsACString& remoteType =
+      ContentParent::Cast(Manager())->GetRemoteType();
+
+  // Only the privileged about content process is allowed to access
+  // things over the page-icon protocol. Any other content process
+  // that tries to send this should have been blocked via the
+  // ScriptSecurityManager, but if somehow the process has been tricked into
+  // sending this message, we send IPC_FAIL in order to crash that
+  // likely-compromised content process.
+  if (remoteType != PRIVILEGEDABOUT_REMOTE_TYPE) {
+    return IPC_FAIL(this, "Wrong process type");
+  }
+
+  if (aLoadInfoArgs.isNothing()) {
+    return IPC_FAIL(this, "Page-icon request must include loadInfo");
+  }
+
+  nsCOMPtr<nsILoadInfo> loadInfo;
+  nsresult rv = mozilla::ipc::LoadInfoArgsToLoadInfo(aLoadInfoArgs, remoteType,
+                                                     getter_AddRefs(loadInfo));
+  if (NS_FAILED(rv)) {
+    return IPC_FAIL(this, "Page-icon request must include loadInfo");
+  }
+
+  RefPtr<PageIconProtocolHandler> ph(PageIconProtocolHandler::GetSingleton());
+  MOZ_ASSERT(ph);
+
+  nsCOMPtr<nsIInputStream> inputStream;
+  bool terminateSender = true;
+  auto inputStreamPromise = ph->NewStream(aURI, loadInfo, &terminateSender);
+
+  if (terminateSender) {
+    return IPC_FAIL(this, "Malformed page-icon request");
+  }
+
+  inputStreamPromise->Then(
+      GetMainThreadSerialEventTarget(), __func__,
+      [aResolver](const RemoteStreamInfo& aInfo) { aResolver(Some(aInfo)); },
+      [aResolver](nsresult aRv) {
+        // If NewStream failed, we send back an invalid stream to the child so
+        // it can handle the error. MozPromise rejection is reserved for channel
+        // errors/disconnects.
+        Unused << NS_WARN_IF(NS_FAILED(aRv));
+        aResolver(Nothing());
+      });
+
+  return IPC_OK();
+#else
+  return IPC_FAIL(this, "page-icon: protocol unavailable");
+#endif
+}
+
+}  // namespace net
+}  // namespace mozilla
diff --git a/netwerk/ipc/NeckoParent.h b/netwerk/ipc/NeckoParent.h
new file mode 100644
index 0000000000..4c8c056c81
--- /dev/null
+++ b/netwerk/ipc/NeckoParent.h
@@ -0,0 +1,217 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/BasePrincipal.h"
+#include "mozilla/net/PNeckoParent.h"
+#include "mozilla/net/NeckoCommon.h"
+#include "nsIAuthPrompt2.h"
+#include "nsINetworkPredictor.h"
+#include "nsNetUtil.h"
+
+#ifndef mozilla_net_NeckoParent_h
+#  define mozilla_net_NeckoParent_h
+
+namespace mozilla {
+namespace net {
+
+// Used to override channel Private Browsing status if needed.
+enum PBOverrideStatus {
+  kPBOverride_Unset = 0,
+  kPBOverride_Private,
+  kPBOverride_NotPrivate
+};
+
+// Header file contents
+class NeckoParent : public PNeckoParent {
+  friend class PNeckoParent;
+
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(NeckoParent, override)
+
+  NeckoParent();
+
+  [[nodiscard]] static const char* GetValidatedOriginAttributes(
+      const SerializedLoadContext& aSerialized, PContentParent* aBrowser,
+      nsIPrincipal* aRequestingPrincipal, mozilla::OriginAttributes& aAttrs);
+
+  /*
+   * Creates LoadContext for parent-side of an e10s channel.
+   *
+   * PContentParent corresponds to the process that is requesting the load.
+   *
+   * Returns null if successful, or an error string if failed.
+   */
+  [[nodiscard]] static const char* CreateChannelLoadContext(
+      PBrowserParent* aBrowser, PContentParent* aContent,
+      const SerializedLoadContext& aSerialized,
+      nsIPrincipal* aRequestingPrincipal, nsCOMPtr<nsILoadContext>& aResult);
+
+  virtual void ActorDestroy(ActorDestroyReason aWhy) override;
+  PCookieServiceParent* AllocPCookieServiceParent();
+  virtual mozilla::ipc::IPCResult RecvPCookieServiceConstructor(
+      PCookieServiceParent* aActor) override {
+    return PNeckoParent::RecvPCookieServiceConstructor(aActor);
+  }
+
+ protected:
+  virtual ~NeckoParent() = default;
+
+  bool mSocketProcessBridgeInited;
+
+  already_AddRefed<PHttpChannelParent> AllocPHttpChannelParent(
+      PBrowserParent*, const SerializedLoadContext&,
+      const HttpChannelCreationArgs& aOpenArgs);
+  virtual mozilla::ipc::IPCResult RecvPHttpChannelConstructor(
+      PHttpChannelParent* aActor, PBrowserParent* aBrowser,
+      const SerializedLoadContext& aSerialized,
+      const HttpChannelCreationArgs& aOpenArgs) override;
+
+  PStunAddrsRequestParent* AllocPStunAddrsRequestParent();
+  bool DeallocPStunAddrsRequestParent(PStunAddrsRequestParent* aActor);
+
+  PWebrtcTCPSocketParent* AllocPWebrtcTCPSocketParent(
+      const Maybe<TabId>& aTabId);
+  bool DeallocPWebrtcTCPSocketParent(PWebrtcTCPSocketParent* aActor);
+
+  PAltDataOutputStreamParent* AllocPAltDataOutputStreamParent(
+      const nsACString& type, const int64_t& predictedSize,
+      PHttpChannelParent* channel);
+  bool DeallocPAltDataOutputStreamParent(PAltDataOutputStreamParent* aActor);
+
+  bool DeallocPCookieServiceParent(PCookieServiceParent*);
+  PWebSocketParent* AllocPWebSocketParent(
+      PBrowserParent* browser, const SerializedLoadContext& aSerialized,
+      const uint32_t& aSerial);
+  bool DeallocPWebSocketParent(PWebSocketParent*);
+  PTCPSocketParent* AllocPTCPSocketParent(const nsAString& host,
+                                          const uint16_t& port);
+
+  already_AddRefed<PDocumentChannelParent> AllocPDocumentChannelParent(
+      const dom::MaybeDiscarded<dom::BrowsingContext>& aContext,
+      const DocumentChannelCreationArgs& args);
+  virtual mozilla::ipc::IPCResult RecvPDocumentChannelConstructor(
+      PDocumentChannelParent* aActor,
+      const dom::MaybeDiscarded<dom::BrowsingContext>& aContext,
+      const DocumentChannelCreationArgs& aArgs) override;
+  bool DeallocPDocumentChannelParent(PDocumentChannelParent* channel);
+
+  bool DeallocPTCPSocketParent(PTCPSocketParent*);
+  PTCPServerSocketParent* AllocPTCPServerSocketParent(
+      const uint16_t& aLocalPort, const uint16_t& aBacklog,
+      const bool& aUseArrayBuffers);
+  virtual mozilla::ipc::IPCResult RecvPTCPServerSocketConstructor(
+      PTCPServerSocketParent*, const uint16_t& aLocalPort,
+      const uint16_t& aBacklog, const bool& aUseArrayBuffers) override;
+  bool DeallocPTCPServerSocketParent(PTCPServerSocketParent*);
+  PUDPSocketParent* AllocPUDPSocketParent(nsIPrincipal* aPrincipal,
+                                          const nsACString& aFilter);
+  virtual mozilla::ipc::IPCResult RecvPUDPSocketConstructor(
+      PUDPSocketParent*, nsIPrincipal* aPrincipal,
+      const nsACString& aFilter) override;
+  bool DeallocPUDPSocketParent(PUDPSocketParent*);
+  already_AddRefed<PDNSRequestParent> AllocPDNSRequestParent(
+      const nsACString& aHost, const nsACString& aTrrServer,
+      const int32_t& aPort, const uint16_t& aType,
+      const OriginAttributes& aOriginAttributes,
+      const nsIDNSService::DNSFlags& aFlags);
+  virtual mozilla::ipc::IPCResult RecvPDNSRequestConstructor(
+      PDNSRequestParent* actor, const nsACString& aHost,
+      const nsACString& trrServer, const int32_t& aPort, const uint16_t& type,
+      const OriginAttributes& aOriginAttributes,
+      const nsIDNSService::DNSFlags& flags) override;
+  mozilla::ipc::IPCResult RecvSpeculativeConnect(
+      nsIURI* aURI, nsIPrincipal* aPrincipal,
+      Maybe<OriginAttributes>&& aOriginAttributes, const bool& aAnonymous);
+  mozilla::ipc::IPCResult RecvHTMLDNSPrefetch(
+      const nsAString& hostname, const bool& isHttps,
+      const OriginAttributes& aOriginAttributes,
+      const nsIDNSService::DNSFlags& flags);
+  mozilla::ipc::IPCResult RecvCancelHTMLDNSPrefetch(
+      const nsAString& hostname, const bool& isHttps,
+      const OriginAttributes& aOriginAttributes,
+      const nsIDNSService::DNSFlags& flags, const nsresult& reason);
+  PWebSocketEventListenerParent* AllocPWebSocketEventListenerParent(
+      const uint64_t& aInnerWindowID);
+  bool DeallocPWebSocketEventListenerParent(PWebSocketEventListenerParent*);
+
+  already_AddRefed<PDataChannelParent> AllocPDataChannelParent(
+      const uint32_t& channelId);
+
+  virtual mozilla::ipc::IPCResult RecvPDataChannelConstructor(
+      PDataChannelParent* aActor, const uint32_t& channelId) override;
+#  ifdef MOZ_WIDGET_GTK
+  PGIOChannelParent* AllocPGIOChannelParent(
+      PBrowserParent* aBrowser, const SerializedLoadContext& aSerialized,
+      const GIOChannelCreationArgs& aOpenArgs);
+  bool DeallocPGIOChannelParent(PGIOChannelParent* channel);
+
+  virtual mozilla::ipc::IPCResult RecvPGIOChannelConstructor(
+      PGIOChannelParent* aActor, PBrowserParent* aBrowser,
+      const SerializedLoadContext& aSerialized,
+      const GIOChannelCreationArgs& aOpenArgs) override;
+#  endif
+  PSimpleChannelParent* AllocPSimpleChannelParent(const uint32_t& channelId);
+  bool DeallocPSimpleChannelParent(PSimpleChannelParent* actor);
+
+  virtual mozilla::ipc::IPCResult RecvPSimpleChannelConstructor(
+      PSimpleChannelParent* aActor, const uint32_t& channelId) override;
+
+  already_AddRefed<PFileChannelParent> AllocPFileChannelParent(
+      const uint32_t& channelId);
+
+  virtual mozilla::ipc::IPCResult RecvPFileChannelConstructor(
+      PFileChannelParent* aActor, const uint32_t& channelId) override;
+
+  PTransportProviderParent* AllocPTransportProviderParent();
+  bool DeallocPTransportProviderParent(PTransportProviderParent* aActor);
+
+  /* Predictor Messages */
+  mozilla::ipc::IPCResult RecvPredPredict(
+      nsIURI* aTargetURI, nsIURI* aSourceURI,
+      const PredictorPredictReason& aReason,
+      const OriginAttributes& aOriginAttributes, const bool& hasVerifier);
+
+  mozilla::ipc::IPCResult RecvPredLearn(
+      nsIURI* aTargetURI, nsIURI* aSourceURI,
+      const PredictorPredictReason& aReason,
+      const OriginAttributes& aOriginAttributes);
+  mozilla::ipc::IPCResult RecvPredReset();
+
+  mozilla::ipc::IPCResult RecvRequestContextLoadBegin(const uint64_t& rcid);
+  mozilla::ipc::IPCResult RecvRequestContextAfterDOMContentLoaded(
+      const uint64_t& rcid);
+  mozilla::ipc::IPCResult RecvRemoveRequestContext(const uint64_t& rcid);
+
+  /* WebExtensions */
+  mozilla::ipc::IPCResult RecvGetExtensionStream(
+      nsIURI* aURI, GetExtensionStreamResolver&& aResolve);
+
+  mozilla::ipc::IPCResult RecvGetExtensionFD(nsIURI* aURI,
+                                             GetExtensionFDResolver&& aResolve);
+
+  /* Page thumbnails remote resource loading */
+  mozilla::ipc::IPCResult RecvGetPageThumbStream(
+      nsIURI* aURI, const Maybe<LoadInfoArgs>& aLoadInfoArgs,
+      GetPageThumbStreamResolver&& aResolve);
+
+  /* Page icon remote resource loading */
+  mozilla::ipc::IPCResult RecvGetPageIconStream(
+      nsIURI* aURI, const Maybe<LoadInfoArgs>& aLoadInfoArgs,
+      GetPageIconStreamResolver&& aResolve);
+
+  mozilla::ipc::IPCResult RecvInitSocketProcessBridge(
+      InitSocketProcessBridgeResolver&& aResolver);
+  mozilla::ipc::IPCResult RecvResetSocketProcessBridge();
+
+  mozilla::ipc::IPCResult RecvEnsureHSTSData(
+      EnsureHSTSDataResolver&& aResolver);
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_net_NeckoParent_h
diff --git a/netwerk/ipc/NeckoTargetHolder.cpp b/netwerk/ipc/NeckoTargetHolder.cpp
new file mode 100644
index 0000000000..90d80ce7d5
--- /dev/null
+++ b/netwerk/ipc/NeckoTargetHolder.cpp
@@ -0,0 +1,38 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "NeckoTargetHolder.h"
+
+#include "nsContentUtils.h"
+
+namespace mozilla {
+namespace net {
+
+already_AddRefed<nsISerialEventTarget> NeckoTargetHolder::GetNeckoTarget() {
+  nsCOMPtr<nsISerialEventTarget> target = mNeckoTarget;
+
+  if (!target) {
+    target = GetMainThreadSerialEventTarget();
+  }
+  return target.forget();
+}
+
+nsresult NeckoTargetHolder::Dispatch(already_AddRefed<nsIRunnable>&& aRunnable,
+                                     uint32_t aDispatchFlags) {
+  if (mNeckoTarget) {
+    return mNeckoTarget->Dispatch(std::move(aRunnable), aDispatchFlags);
+  }
+
+  nsCOMPtr<nsISerialEventTarget> mainThreadTarget =
+      GetMainThreadSerialEventTarget();
+  MOZ_ASSERT(mainThreadTarget);
+
+  return mainThreadTarget->Dispatch(std::move(aRunnable), aDispatchFlags);
+}
+
+}  // namespace net
+}  // namespace mozilla
diff --git a/netwerk/ipc/NeckoTargetHolder.h b/netwerk/ipc/NeckoTargetHolder.h
new file mode 100644
index 0000000000..254d6f138f
--- /dev/null
+++ b/netwerk/ipc/NeckoTargetHolder.h
@@ -0,0 +1,40 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_NeckoTargetHolder_h
+#define mozilla_net_NeckoTargetHolder_h
+
+#include "nsIEventTarget.h"
+#include "nsThreadUtils.h"
+
+namespace mozilla {
+namespace net {
+
+// A helper class that implements GetNeckoTarget(). Basically, all e10s child
+// channels should inherit this class in order to get a labeled event target.
+class NeckoTargetHolder {
+ public:
+  explicit NeckoTargetHolder(nsISerialEventTarget* aNeckoTarget)
+      : mNeckoTarget(aNeckoTarget) {}
+
+ protected:
+  virtual ~NeckoTargetHolder() = default;
+  // Get event target for processing network events.
+  virtual already_AddRefed<nsISerialEventTarget> GetNeckoTarget();
+  // When |mNeckoTarget| is not null, use it to dispatch the runnable.
+  // Otherwise, dispatch the runnable to the main thread.
+  nsresult Dispatch(already_AddRefed<nsIRunnable>&& aRunnable,
+                    uint32_t aDispatchFlags = NS_DISPATCH_NORMAL);
+
+  // EventTarget for labeling networking events.
+  nsCOMPtr<nsISerialEventTarget> mNeckoTarget;
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif
diff --git a/netwerk/ipc/PDataChannel.ipdl b/netwerk/ipc/PDataChannel.ipdl
new file mode 100644
index 0000000000..52d8642ff7
--- /dev/null
+++ b/netwerk/ipc/PDataChannel.ipdl
@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 ft=cpp : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include protocol PNecko;
+
+namespace mozilla {
+namespace net {
+
+[ChildImpl=virtual]
+async protocol PDataChannel
+{
+  manager PNecko;
+
+parent:
+  // Note: channels are opened during construction, so no open method here:
+  // see PNecko.ipdl
+  async __delete__();
+};
+
+} // namespace net
+} // namespace mozilla
diff --git a/netwerk/ipc/PDocumentChannel.ipdl b/netwerk/ipc/PDocumentChannel.ipdl
new file mode 100644
index 0000000000..1e40052a25
--- /dev/null
+++ b/netwerk/ipc/PDocumentChannel.ipdl
@@ -0,0 +1,66 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 ft=cpp : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include protocol PNecko;
+include protocol PStreamFilter;
+include InputStreamParams;
+include PBackgroundSharedTypes;
+include NeckoChannelParams;
+include IPCServiceWorkerDescriptor;
+include IPCStream;
+include DOMTypes;
+
+include "mozilla/net/NeckoMessageUtils.h";
+
+using class mozilla::net::nsHttpHeaderArray from "nsHttpHeaderArray.h";
+using mozilla::net::NetAddr from "mozilla/net/DNS.h";
+
+namespace mozilla {
+namespace net {
+
+protocol PDocumentChannel
+{
+  manager PNecko;
+
+parent:
+
+  async Cancel(nsresult status, nsCString reason);
+
+  async __delete__();
+
+child:
+
+  // Used to cancel child channel if we hit errors during creating and
+  // AsyncOpen of nsHttpChannel on the parent.
+  async FailedAsyncOpen(nsresult status);
+
+  // This message is sent to a child that has been redirected to another process.
+  // As a consequence, it should cleanup the channel listeners and remove the
+  // request from the loadGroup.
+  // aStatus must be an error result.
+  // aLoadGroupReason is used as mStatus when we remove the child channel from
+  // the loadgroup (but aStatus is passed as the parameter to RemoveRequest).
+  // We do this so we can remove using NS_BINDING_RETARGETED, but still have the
+  // channel not be in an error state.
+  async DisconnectChildListeners(nsresult aStatus, nsresult aLoadGroupReason, bool aContinueNavigating);
+
+  // Triggers replacing this DocumentChannel with a 'real' channel (like PHttpChannel),
+  // and notifies the listener via a redirect to the new channel.
+  async RedirectToRealChannel(RedirectToRealChannelArgs args, Endpoint<PStreamFilterParent>[] aEndpoint)
+      returns (nsresult rv);
+
+  // May only be called on a DocumentChannel created by nsObjectLoadingContent
+  // for an object or embed element load.
+  //
+  // Promotes the load from an object load to a proper document load, and
+  // returns the `BrowsingContext` which should be used to host the final load.
+  async UpgradeObjectLoad() returns (MaybeDiscardedBrowsingContext frameContext);
+};
+
+} // namespace net
+} // namespace mozilla
+
diff --git a/netwerk/ipc/PFileChannel.ipdl b/netwerk/ipc/PFileChannel.ipdl
new file mode 100644
index 0000000000..8f86fc81b1
--- /dev/null
+++ b/netwerk/ipc/PFileChannel.ipdl
@@ -0,0 +1,28 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=2 sts=2 et tw=80 ft=cpp : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include protocol PNecko;
+
+namespace mozilla {
+namespace net {
+
+/* Used to facilitate http redirects to file:// - see
+ * https://bugzilla.mozilla.org/show_bug.cgi?id=1345094
+ */
+[ChildImpl=virtual]
+async protocol PFileChannel
+{
+  manager PNecko;
+
+parent:
+  // Note: channels are opened during construction, so no open method here:
+  // see PNecko.ipdl
+  async __delete__();
+};
+
+} // namespace net
+} // namespace mozilla
diff --git a/netwerk/ipc/PInputChannelThrottleQueue.ipdl b/netwerk/ipc/PInputChannelThrottleQueue.ipdl
new file mode 100644
index 0000000000..b95d9cc77f
--- /dev/null
+++ b/netwerk/ipc/PInputChannelThrottleQueue.ipdl
@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 ft=cpp : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include protocol PSocketProcess;
+
+namespace mozilla {
+namespace net {
+
+protocol PInputChannelThrottleQueue
+{
+  manager PSocketProcess;
+
+parent:
+  async RecordRead(uint32_t aBytesRead);
+
+child:
+  async __delete__();
+};
+
+} // namespace net
+} // namespace mozilla
diff --git a/netwerk/ipc/PNecko.ipdl b/netwerk/ipc/PNecko.ipdl
new file mode 100644
index 0000000000..698ae38e7e
--- /dev/null
+++ b/netwerk/ipc/PNecko.ipdl
@@ -0,0 +1,178 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 ft=cpp : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include protocol PContent;
+include protocol PHttpChannel;
+include protocol PCookieService;
+include protocol PBrowser;
+#ifdef MOZ_WIDGET_GTK
+include protocol PGIOChannel;
+#endif
+include protocol PWebSocket;
+include protocol PWebSocketEventListener;
+include protocol PTCPSocket;
+include protocol PTCPServerSocket;
+include protocol PUDPSocket;
+include protocol PDNSRequest;
+include protocol PDataChannel;
+include protocol PSimpleChannel;
+include protocol PTransportProvider;
+include protocol PStunAddrsRequest;
+include protocol PFileChannel;
+include protocol PWebrtcTCPSocket;
+include protocol PSocketProcessBridge;
+include protocol PDocumentChannel;
+
+include IPCStream;
+include NeckoChannelParams;
+include protocol PAltDataOutputStream;
+
+include "mozilla/dom/PermissionMessageUtils.h";
+
+using mozilla::dom::MaybeDiscardedBrowsingContext from "mozilla/dom/BrowsingContext.h";
+using class IPC::SerializedLoadContext from "SerializedLoadContext.h";
+using mozilla::dom::TabId from "mozilla/dom/ipc/IdType.h";
+using nsIDNSService::DNSFlags from "nsIDNSService.h";
+[RefCounted] using class nsIInputStream from "mozilla/ipc/IPCStreamUtils.h";
+[RefCounted] using class nsIURI from "mozilla/ipc/URIUtils.h";
+[RefCounted] using class nsIPrincipal from "nsIPrincipal.h";
+
+
+namespace mozilla {
+namespace net {
+
+//-------------------------------------------------------------------
+[NestedUpTo=inside_cpow] sync protocol PNecko
+{
+  manager PContent;
+  manages PHttpChannel;
+  manages PCookieService;
+  manages PWebSocket;
+  manages PWebSocketEventListener;
+  manages PTCPSocket;
+  manages PTCPServerSocket;
+  manages PUDPSocket;
+  manages PDNSRequest;
+  manages PDataChannel;
+#ifdef MOZ_WIDGET_GTK
+  manages PGIOChannel;
+#endif
+  manages PSimpleChannel;
+  manages PFileChannel;
+  manages PTransportProvider;
+  manages PAltDataOutputStream;
+  manages PStunAddrsRequest;
+  manages PWebrtcTCPSocket;
+  manages PDocumentChannel;
+
+parent:
+  async __delete__();
+
+  [Nested=inside_cpow] async PCookieService();
+  async PHttpChannel(nullable PBrowser browser,
+                     SerializedLoadContext loadContext,
+                     HttpChannelCreationArgs args);
+
+  async PWebSocket(nullable PBrowser browser, SerializedLoadContext loadContext,
+                   uint32_t aSerialID);
+  async PTCPServerSocket(uint16_t localPort, uint16_t backlog, bool useArrayBuffers);
+  async PUDPSocket(nullable nsIPrincipal principal, nsCString filter);
+
+  async PDNSRequest(nsCString hostName, nsCString trrServer, int32_t port,
+                    uint16_t type, OriginAttributes originAttributes,
+                    DNSFlags flags);
+
+  async PDocumentChannel(MaybeDiscardedBrowsingContext browsingContext,
+                         DocumentChannelCreationArgs args);
+
+  async PWebSocketEventListener(uint64_t aInnerWindowID);
+
+  /* Predictor Methods */
+  async PredPredict(nullable nsIURI targetURI, nullable nsIURI sourceURI,
+                    uint32_t reason, OriginAttributes originAttributes,
+                    bool hasVerifier);
+  async PredLearn(nullable nsIURI targetURI, nullable nsIURI sourceURI,
+                  uint32_t reason, OriginAttributes originAttributes);
+  async PredReset();
+
+  async SpeculativeConnect(nullable nsIURI uri,
+                           nullable nsIPrincipal principal,
+                           OriginAttributes? originAttributes,
+                           bool anonymous);
+  async HTMLDNSPrefetch(nsString hostname, bool isHttps,
+                        OriginAttributes originAttributes, DNSFlags flags);
+  async CancelHTMLDNSPrefetch(nsString hostname, bool isHttps,
+                              OriginAttributes originAttributes,
+                              DNSFlags flags, nsresult reason);
+
+  /**
+   * channelId is used to establish a connection between redirect channels in
+   * the parent and the child when we're redirecting to a data: URI.
+   */
+  async PDataChannel(uint32_t channelId);
+#ifdef MOZ_WIDGET_GTK
+  async PGIOChannel(nullable PBrowser browser, SerializedLoadContext loadContext, GIOChannelCreationArgs args);
+#endif
+  async PSimpleChannel(uint32_t channelId);
+  async PFileChannel(uint32_t channelId);
+
+  async RequestContextLoadBegin(uint64_t rcid);
+  async RequestContextAfterDOMContentLoaded(uint64_t rcid);
+  async RemoveRequestContext(uint64_t rcid);
+
+  async PAltDataOutputStream(nsCString type, int64_t predictedSize, PHttpChannel channel);
+
+  async PStunAddrsRequest();
+
+  /* tabId is only required for web-proxy support, which isn't always needed */
+  async PWebrtcTCPSocket(TabId? tabId);
+
+  /**
+   * WebExtension-specific remote resource loading
+   */
+  async GetExtensionStream(nullable nsIURI uri) returns (nullable nsIInputStream stream);
+  async GetExtensionFD(nullable nsIURI uri) returns (FileDescriptor fd);
+
+  async InitSocketProcessBridge()
+    returns (Endpoint<PSocketProcessBridgeChild> endpoint);
+  async ResetSocketProcessBridge();
+
+  async EnsureHSTSData()
+    returns (bool result);
+
+  /**
+   * Page thumbnails remote resource loading
+   */
+  async GetPageThumbStream(nullable nsIURI uri, LoadInfoArgs? loadInfo) returns (RemoteStreamInfo? info);
+  async GetPageIconStream(nullable nsIURI uri, LoadInfoArgs? loadInfo) returns (RemoteStreamInfo? info);
+
+child:
+  /* Predictor Methods */
+  async PredOnPredictPrefetch(nullable nsIURI uri, uint32_t httpStatus);
+  async PredOnPredictPreconnect(nullable nsIURI uri);
+  async PredOnPredictDNS(nullable nsIURI uri);
+
+  async SpeculativeConnectRequest();
+
+  // Using medium high priority to deliver this notification possibly sooner than we
+  // enter poll() on the child process with infinite timeout.
+  [Priority=mediumhigh] async NetworkChangeNotification(nsCString type);
+
+  async PTransportProvider();
+
+  async SetTRRDomain(nsCString domain);
+
+both:
+  // Actually we need PTCPSocket() for parent. But ipdl disallows us having different
+  // signatures on parent and child. So when constructing the parent side object, we just
+  // leave host/port unused.
+  async PTCPSocket(nsString host, uint16_t port);
+};
+
+
+} // namespace net
+} // namespace mozilla
diff --git a/netwerk/ipc/PProxyAutoConfig.ipdl b/netwerk/ipc/PProxyAutoConfig.ipdl
new file mode 100644
index 0000000000..1058397433
--- /dev/null
+++ b/netwerk/ipc/PProxyAutoConfig.ipdl
@@ -0,0 +1,20 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et 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/. */
+
+namespace mozilla {
+namespace net {
+
+sync protocol PProxyAutoConfig
+{
+child:
+  async ConfigurePAC(nsCString aPACURI, nsCString aPACScriptData,
+                     bool aIncludePath, uint32_t aExtraHeapSize);
+  async GetProxyForURI(nsCString aTestURI, nsCString aTestHost)
+    returns (nsresult aStatus, nsCString aResult);
+};
+
+} // namespace net
+} // namespace mozilla
diff --git a/netwerk/ipc/PProxyConfigLookup.ipdl b/netwerk/ipc/PProxyConfigLookup.ipdl
new file mode 100644
index 0000000000..9aaaf5fbcb
--- /dev/null
+++ b/netwerk/ipc/PProxyConfigLookup.ipdl
@@ -0,0 +1,21 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include protocol PSocketProcess;
+
+include NeckoChannelParams;
+
+namespace mozilla {
+namespace net {
+
+async protocol PProxyConfigLookup
+{
+  manager PSocketProcess;
+
+child:
+  async __delete__(ProxyInfoCloneArgs[] aProxyInfo, nsresult aResult);
+};
+
+} // namespace net
+} // namespace mozilla
diff --git a/netwerk/ipc/PSimpleChannel.ipdl b/netwerk/ipc/PSimpleChannel.ipdl
new file mode 100644
index 0000000000..cae7fe8f1b
--- /dev/null
+++ b/netwerk/ipc/PSimpleChannel.ipdl
@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 ft=cpp : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include protocol PNecko;
+
+namespace mozilla {
+namespace net {
+
+[ManualDealloc, ChildImpl=virtual]
+async protocol PSimpleChannel
+{
+  manager PNecko;
+
+parent:
+  // Note: channels are opened during construction, so no open method here:
+  // see PNecko.ipdl
+  async __delete__();
+};
+
+} // namespace net
+} // namespace mozilla
diff --git a/netwerk/ipc/PSocketProcess.ipdl b/netwerk/ipc/PSocketProcess.ipdl
new file mode 100644
index 0000000000..6a922ab574
--- /dev/null
+++ b/netwerk/ipc/PSocketProcess.ipdl
@@ -0,0 +1,223 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include protocol PDNSRequest;
+include protocol PSocketProcessBridge;
+include protocol PProfiler;
+include protocol PWebrtcTCPSocket;
+include protocol PHttpTransaction;
+include protocol PHttpConnectionMgr;
+include protocol PInputChannelThrottleQueue;
+include protocol PBackgroundStarter;
+include protocol PAltService;
+include protocol PAltSvcTransaction;
+include protocol PTRRService;
+include protocol PProxyConfigLookup;
+include protocol PNativeDNSResolverOverride;
+include protocol PProxyAutoConfig;
+
+#if defined(MOZ_SANDBOX) && defined(MOZ_DEBUG) && defined(ENABLE_TESTS)
+include protocol PSandboxTesting;
+#endif
+
+include MemoryReportTypes;
+include NeckoChannelParams;
+include PrefsTypes;
+include PSMIPCTypes;
+
+include "mozilla/ipc/ByteBufUtils.h";
+
+using mozilla::dom::NativeThreadId from "mozilla/dom/NativeThreadId.h";
+using mozilla::dom::TabId from "mozilla/dom/ipc/IdType.h";
+using mozilla::Telemetry::HistogramAccumulation from "mozilla/TelemetryComms.h";
+using mozilla::Telemetry::KeyedHistogramAccumulation from "mozilla/TelemetryComms.h";
+using mozilla::Telemetry::ScalarAction from "mozilla/TelemetryComms.h";
+using mozilla::Telemetry::KeyedScalarAction from "mozilla/TelemetryComms.h";
+using mozilla::Telemetry::ChildEventData from "mozilla/TelemetryComms.h";
+using mozilla::Telemetry::DiscardedData from "mozilla/TelemetryComms.h";
+using base::ProcessId from "base/process.h";
+using mozilla::OriginAttributes from "mozilla/ipc/BackgroundUtils.h";
+using PRTime from "prtime.h";
+[RefCounted] using class nsIURI from "mozilla/ipc/URIUtils.h";
+using struct nsID from "nsID.h";
+using mozilla::net::SocketInfo from "mozilla/net/DashboardTypes.h";
+using mozilla::net::DNSCacheEntries from "mozilla/net/DashboardTypes.h";
+using mozilla::net::HttpRetParams from "mozilla/net/DashboardTypes.h";
+using nsIDNSService::DNSFlags from "nsIDNSService.h";
+
+#if defined(XP_WIN)
+[MoveOnly] using mozilla::UntrustedModulesData from "mozilla/UntrustedModulesData.h";
+[MoveOnly] using mozilla::ModulePaths from "mozilla/UntrustedModulesData.h";
+[MoveOnly] using mozilla::ModulesMapResult from "mozilla/UntrustedModulesData.h";
+#endif  // defined(XP_WIN)
+
+namespace mozilla {
+namespace net {
+
+struct HttpHandlerInitArgs {
+  nsCString mLegacyAppName;
+  nsCString mLegacyAppVersion;
+  nsCString mPlatform;
+  nsCString mOscpu;
+  nsCString mMisc;
+  nsCString mProduct;
+  nsCString mProductSub;
+  nsCString mAppName;
+  nsCString mAppVersion;
+  nsCString mCompatFirefox;
+  nsCString mCompatDevice;
+  nsCString mDeviceModelId;
+};
+
+struct SocketDataArgs
+{
+  uint64_t totalSent;
+  uint64_t totalRecv;
+  SocketInfo[] info;
+};
+
+struct SocketPorcessInitAttributes {
+  bool mOffline;
+  bool mConnectivity;
+  bool mInitSandbox;
+#if defined(XP_WIN)
+  bool mIsReadyForBackgroundProcessing;
+#endif
+  FileDescriptor? mSandboxBroker;
+};
+
+[NeedsOtherPid]
+sync protocol PSocketProcess
+{
+  manages PDNSRequest;
+  manages PWebrtcTCPSocket;
+  manages PHttpTransaction;
+  manages PHttpConnectionMgr;
+  manages PInputChannelThrottleQueue;
+  manages PAltService;
+  manages PAltSvcTransaction;
+  manages PTRRService;
+  manages PProxyConfigLookup;
+  manages PNativeDNSResolverOverride;
+
+parent:
+  async InitCrashReporter(NativeThreadId threadId);
+  async AddMemoryReport(MemoryReport aReport);
+  // Messages for sending telemetry to parent process.
+  async AccumulateChildHistograms(HistogramAccumulation[] accumulations);
+  async AccumulateChildKeyedHistograms(KeyedHistogramAccumulation[] accumulations);
+  async UpdateChildScalars(ScalarAction[] actions);
+  async UpdateChildKeyedScalars(KeyedScalarAction[] actions);
+  async RecordChildEvents(ChildEventData[] events);
+  async RecordDiscardedData(DiscardedData data);
+
+  /* tabId is only required for web-proxy support, which isn't always needed */
+  async PWebrtcTCPSocket(TabId? tabId);
+  async ObserveHttpActivity(HttpActivityArgs aActivityArgs,
+                            uint32_t aActivityType,
+                            uint32_t aActivitySubtype,
+                            PRTime   aTimestamp,
+                            uint64_t aExtraSizeData,
+                            nsCString aExtraStringData);
+  async InitBackground(Endpoint<PBackgroundStarterParent> aEndpoint);
+  async PAltService();
+  async PProxyConfigLookup(nullable nsIURI aUri, uint32_t aFlags);
+  async CachePushCheck(nullable nsIURI aPushedURL,
+                       OriginAttributes aOriginAttributes,
+                       nsCString aRequestString)
+    returns (bool aAccepted);
+
+  async ExcludeHttp2OrHttp3(HttpConnectionInfoCloneArgs aArgs);
+
+  async OnConsoleMessage(nsString aMessage);
+
+  // Sent from time-to-time to limit the amount of telemetry vulnerable to loss
+  // Buffer contains bincoded Rust structs.
+  // https://firefox-source-docs.mozilla.org/toolkit/components/glean/dev/ipc.html
+  async FOGData(ByteBuf buf);
+
+#if defined(XP_WIN)
+  async GetModulesTrust(ModulePaths aModPaths, bool aRunAtNormalPriority)
+      returns (ModulesMapResult? modMapResult);
+#endif  // defined(XP_WIN)
+
+child:
+  async Init(SocketPorcessInitAttributes aAttributes);
+  async PreferenceUpdate(Pref pref);
+  async RequestMemoryReport(uint32_t generation,
+                            bool anonymize,
+                            bool minimizeMemoryUsage,
+                            FileDescriptor? DMDFile)
+      returns (uint32_t aGeneration);
+  async SetOffline(bool offline);
+  async SetConnectivity(bool connectivity);
+  async InitLinuxSandbox(FileDescriptor? sandboxBroker);
+  async InitSocketProcessBridgeParent(ProcessId processId, Endpoint<PSocketProcessBridgeParent> endpoint);
+  async InitProfiler(Endpoint<PProfilerChild> aEndpoint);
+#if defined(MOZ_SANDBOX) && defined(MOZ_DEBUG) && defined(ENABLE_TESTS)
+  async InitSandboxTesting(Endpoint<PSandboxTestingChild> aEndpoint);
+#endif
+  // test-only
+  async SocketProcessTelemetryPing();
+
+  async PHttpTransaction();
+  async PHttpConnectionMgr(HttpHandlerInitArgs aArgs);
+  async UpdateDeviceModelId(nsCString aModelId);
+
+  async OnHttpActivityDistributorActivated(bool aIsActivated);
+  async OnHttpActivityDistributorObserveProxyResponse(bool aIsEnabled);
+  async OnHttpActivityDistributorObserveConnection(bool aIsEnabled);
+  async PInputChannelThrottleQueue(uint32_t meanBytesPerSecond,
+                                   uint32_t maxBytesPerSecond);
+  async PAltSvcTransaction(HttpConnectionInfoCloneArgs aConnInfo,
+                           uint32_t aCaps);
+  async ClearSessionCache() returns (void_t ok);
+  async PTRRService(bool aCaptiveIsPassed,
+                    bool aParentalControlEnabled,
+                    nsCString[] aDNSSuffixList);
+  async PNativeDNSResolverOverride();
+  async NotifyObserver(nsCString aTopic, nsString aData);
+
+  async GetSocketData()
+    returns (SocketDataArgs data);
+  async GetDNSCacheEntries()
+    returns (DNSCacheEntries[] entries);
+   async GetHttpConnectionData()
+    returns (HttpRetParams[] params);
+
+  async InitProxyAutoConfigChild(Endpoint<PProxyAutoConfigChild> endpoint);
+
+  async RecheckIPConnectivity();
+  async RecheckDNS();
+
+  // Tells the Socket process to flush any pending telemetry.
+  // Used in tests and ping assembly. Buffer contains bincoded Rust structs.
+  // https://firefox-source-docs.mozilla.org/toolkit/components/glean/dev/ipc.html
+  async FlushFOGData() returns (ByteBuf buf);
+
+  // Test-only method.
+  // Asks the Socket process to trigger test-only instrumentation.
+  // The unused returned value is to have a promise we can await.
+  async TestTriggerMetrics() returns (bool unused);
+
+#if defined(XP_WIN)
+  async GetUntrustedModulesData() returns (UntrustedModulesData? data);
+
+  /**
+  * This method is used to notifty a child process to start
+  * processing module loading events in UntrustedModulesProcessor.
+  * This should be called when the parent process has gone idle.
+  */
+  async UnblockUntrustedModulesThread();
+#endif  // defined(XP_WIN)
+
+both:
+  async PDNSRequest(nsCString hostName, nsCString trrServer, int32_t port,
+                    uint16_t type, OriginAttributes originAttributes,
+                    DNSFlags flags);
+};
+
+} // namespace net
+} // namespace mozilla
diff --git a/netwerk/ipc/PSocketProcessBridge.ipdl b/netwerk/ipc/PSocketProcessBridge.ipdl
new file mode 100644
index 0000000000..3dd4035b9e
--- /dev/null
+++ b/netwerk/ipc/PSocketProcessBridge.ipdl
@@ -0,0 +1,31 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include protocol PBackgroundStarter;
+
+namespace mozilla {
+namespace net {
+
+/**
+  * PSocketProcessBridge is the IPC protocol between content process and
+  * socket process. This protocol allows socket process to send data to
+  * content process bypassing parent process.
+  * Once created, PSocketProcessBridgeChild is the actor that lives in
+  * content process and PSocketProcessBridgeParent lives in
+  * socket process.
+  */
+[NeedsOtherPid]
+sync protocol PSocketProcessBridge
+{
+
+parent:
+  async InitBackground(Endpoint<PBackgroundStarterParent> aEndpoint);
+both:
+  async Test();
+};
+
+}
+}
diff --git a/netwerk/ipc/ParentChannelWrapper.cpp b/netwerk/ipc/ParentChannelWrapper.cpp
new file mode 100644
index 0000000000..3b89e3e38f
--- /dev/null
+++ b/netwerk/ipc/ParentChannelWrapper.cpp
@@ -0,0 +1,101 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ParentChannelWrapper.h"
+#include "mozilla/net/HttpBaseChannel.h"
+#include "mozilla/net/UrlClassifierCommon.h"
+#include "mozilla/net/RedirectChannelRegistrar.h"
+#include "nsIViewSourceChannel.h"
+#include "nsNetUtil.h"
+#include "nsQueryObject.h"
+#include "mozilla/dom/RemoteType.h"
+
+namespace mozilla {
+namespace net {
+
+NS_IMPL_ISUPPORTS(ParentChannelWrapper, nsIParentChannel, nsIStreamListener,
+                  nsIRequestObserver);
+
+void ParentChannelWrapper::Register(uint64_t aRegistrarId) {
+  nsCOMPtr<nsIRedirectChannelRegistrar> registrar =
+      RedirectChannelRegistrar::GetOrCreate();
+  nsCOMPtr<nsIChannel> dummy;
+  MOZ_ALWAYS_SUCCEEDS(
+      NS_LinkRedirectChannels(aRegistrarId, this, getter_AddRefs(dummy)));
+
+#ifdef DEBUG
+  // The channel registered with the RedirectChannelRegistrar will be the inner
+  // channel when dealing with view-source loads.
+  if (nsCOMPtr<nsIViewSourceChannel> viewSource = do_QueryInterface(mChannel)) {
+    MOZ_ASSERT(dummy == viewSource->GetInnerChannel());
+  } else {
+    MOZ_ASSERT(dummy == mChannel);
+  }
+#endif
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// nsIParentChannel
+////////////////////////////////////////////////////////////////////////////////
+
+NS_IMETHODIMP
+ParentChannelWrapper::SetParentListener(
+    mozilla::net::ParentChannelListener* listener) {
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+ParentChannelWrapper::SetClassifierMatchedInfo(const nsACString& aList,
+                                               const nsACString& aProvider,
+                                               const nsACString& aFullHash) {
+  nsCOMPtr<nsIClassifiedChannel> classifiedChannel =
+      do_QueryInterface(mChannel);
+  if (classifiedChannel) {
+    classifiedChannel->SetMatchedInfo(aList, aProvider, aFullHash);
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+ParentChannelWrapper::SetClassifierMatchedTrackingInfo(
+    const nsACString& aLists, const nsACString& aFullHash) {
+  nsCOMPtr<nsIClassifiedChannel> classifiedChannel =
+      do_QueryInterface(mChannel);
+  if (classifiedChannel) {
+    nsTArray<nsCString> lists, fullhashes;
+    for (const nsACString& token : aLists.Split(',')) {
+      lists.AppendElement(token);
+    }
+    for (const nsACString& token : aFullHash.Split(',')) {
+      fullhashes.AppendElement(token);
+    }
+    classifiedChannel->SetMatchedTrackingInfo(lists, fullhashes);
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+ParentChannelWrapper::NotifyClassificationFlags(uint32_t aClassificationFlags,
+                                                bool aIsThirdParty) {
+  UrlClassifierCommon::SetClassificationFlagsHelper(
+      mChannel, aClassificationFlags, aIsThirdParty);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+ParentChannelWrapper::Delete() { return NS_OK; }
+
+NS_IMETHODIMP
+ParentChannelWrapper::GetRemoteType(nsACString& aRemoteType) {
+  aRemoteType = NOT_REMOTE_TYPE;
+  return NS_OK;
+}
+
+}  // namespace net
+}  // namespace mozilla
+
+#undef LOG
diff --git a/netwerk/ipc/ParentChannelWrapper.h b/netwerk/ipc/ParentChannelWrapper.h
new file mode 100644
index 0000000000..8d7d6dd73d
--- /dev/null
+++ b/netwerk/ipc/ParentChannelWrapper.h
@@ -0,0 +1,39 @@
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_ParentChannelWrapper_h
+#define mozilla_net_ParentChannelWrapper_h
+
+#include "nsIParentChannel.h"
+#include "nsIStreamListener.h"
+
+namespace mozilla {
+namespace net {
+
+class ParentChannelWrapper : public nsIParentChannel {
+ public:
+  ParentChannelWrapper(nsIChannel* aChannel, nsIStreamListener* aListener)
+      : mChannel(aChannel), mListener(aListener) {}
+
+  // Registers this nsIParentChannel wrapper with the RedirectChannelRegistrar
+  // and holds a reference.
+  void Register(uint64_t aRegistrarId);
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIPARENTCHANNEL
+  NS_FORWARD_NSISTREAMLISTENER(mListener->)
+  NS_FORWARD_NSIREQUESTOBSERVER(mListener->)
+
+ private:
+  virtual ~ParentChannelWrapper() = default;
+  const nsCOMPtr<nsIChannel> mChannel;
+  const nsCOMPtr<nsIStreamListener> mListener;
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_net_ParentChannelWrapper_h
diff --git a/netwerk/ipc/ParentProcessDocumentChannel.cpp b/netwerk/ipc/ParentProcessDocumentChannel.cpp
new file mode 100644
index 0000000000..5732122121
--- /dev/null
+++ b/netwerk/ipc/ParentProcessDocumentChannel.cpp
@@ -0,0 +1,314 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ParentProcessDocumentChannel.h"
+
+#include "mozilla/extensions/StreamFilterParent.h"
+#include "mozilla/net/ParentChannelWrapper.h"
+#include "mozilla/net/UrlClassifierCommon.h"
+#include "mozilla/StaticPrefs_extensions.h"
+#include "nsCRT.h"
+#include "nsDocShell.h"
+#include "nsIObserverService.h"
+#include "nsIClassifiedChannel.h"
+#include "nsIXULRuntime.h"
+#include "nsHttpHandler.h"
+#include "nsDocShellLoadState.h"
+
+extern mozilla::LazyLogModule gDocumentChannelLog;
+#define LOG(fmt) MOZ_LOG(gDocumentChannelLog, mozilla::LogLevel::Verbose, fmt)
+
+namespace mozilla {
+namespace net {
+
+using RedirectToRealChannelPromise =
+    typename PDocumentChannelParent::RedirectToRealChannelPromise;
+
+NS_IMPL_ISUPPORTS_INHERITED(ParentProcessDocumentChannel, DocumentChannel,
+                            nsIAsyncVerifyRedirectCallback, nsIObserver)
+
+ParentProcessDocumentChannel::ParentProcessDocumentChannel(
+    nsDocShellLoadState* aLoadState, class LoadInfo* aLoadInfo,
+    nsLoadFlags aLoadFlags, uint32_t aCacheKey, bool aUriModified,
+    bool aIsXFOError)
+    : DocumentChannel(aLoadState, aLoadInfo, aLoadFlags, aCacheKey,
+                      aUriModified, aIsXFOError) {
+  LOG(("ParentProcessDocumentChannel ctor [this=%p]", this));
+}
+
+ParentProcessDocumentChannel::~ParentProcessDocumentChannel() {
+  LOG(("ParentProcessDocumentChannel dtor [this=%p]", this));
+}
+
+RefPtr<RedirectToRealChannelPromise>
+ParentProcessDocumentChannel::RedirectToRealChannel(
+    nsTArray<ipc::Endpoint<extensions::PStreamFilterParent>>&&
+        aStreamFilterEndpoints,
+    uint32_t aRedirectFlags, uint32_t aLoadFlags,
+    const nsTArray<EarlyHintConnectArgs>& aEarlyHints) {
+  LOG(("ParentProcessDocumentChannel RedirectToRealChannel [this=%p]", this));
+  nsCOMPtr<nsIChannel> channel = mDocumentLoadListener->GetChannel();
+  channel->SetLoadFlags(aLoadFlags);
+  channel->SetNotificationCallbacks(mCallbacks);
+
+  if (mLoadGroup) {
+    channel->SetLoadGroup(mLoadGroup);
+  }
+
+  if (XRE_IsE10sParentProcess()) {
+    nsCOMPtr<nsIURI> uri;
+    MOZ_ALWAYS_SUCCEEDS(NS_GetFinalChannelURI(channel, getter_AddRefs(uri)));
+    if (!nsDocShell::CanLoadInParentProcess(uri)) {
+      nsAutoCString msg;
+      uri->GetSpec(msg);
+      msg.Insert(
+          "Attempt to load a non-authorised load in the parent process: ", 0);
+      NS_ASSERTION(false, msg.get());
+      return RedirectToRealChannelPromise::CreateAndResolve(
+          NS_ERROR_CONTENT_BLOCKED, __func__);
+    }
+  }
+  mStreamFilterEndpoints = std::move(aStreamFilterEndpoints);
+
+  if (mDocumentLoadListener->IsDocumentLoad() &&
+      mozilla::SessionHistoryInParent() && GetDocShell() &&
+      mDocumentLoadListener->GetLoadingSessionHistoryInfo()) {
+    GetDocShell()->SetLoadingSessionHistoryInfo(
+        *mDocumentLoadListener->GetLoadingSessionHistoryInfo());
+  }
+
+  RefPtr<RedirectToRealChannelPromise> p = mPromise.Ensure(__func__);
+  // We make the promise use direct task dispatch in order to reduce the number
+  // of event loops iterations.
+  mPromise.UseDirectTaskDispatch(__func__);
+
+  nsresult rv =
+      gHttpHandler->AsyncOnChannelRedirect(this, channel, aRedirectFlags);
+  if (NS_FAILED(rv)) {
+    LOG(
+        ("ParentProcessDocumentChannel RedirectToRealChannel "
+         "AsyncOnChannelRedirect failed [this=%p "
+         "aRv=%d]",
+         this, int(rv)));
+    OnRedirectVerifyCallback(rv);
+  }
+
+  return p;
+}
+
+NS_IMETHODIMP
+ParentProcessDocumentChannel::OnRedirectVerifyCallback(nsresult aResult) {
+  LOG(
+      ("ParentProcessDocumentChannel OnRedirectVerifyCallback [this=%p "
+       "aResult=%d]",
+       this, int(aResult)));
+
+  MOZ_ASSERT(mDocumentLoadListener);
+
+  if (NS_FAILED(aResult)) {
+    Cancel(aResult);
+  } else if (mCanceled) {
+    aResult = NS_ERROR_ABORT;
+  } else {
+    const nsCOMPtr<nsIChannel> channel = mDocumentLoadListener->GetChannel();
+    mLoadGroup->AddRequest(channel, nullptr);
+    // Adding the channel to the loadgroup could have triggered a status
+    // change with an observer being called destroying the docShell, resulting
+    // in the PPDC to be canceled.
+    if (mCanceled) {
+      aResult = NS_ERROR_ABORT;
+    } else {
+      mLoadGroup->RemoveRequest(this, nullptr, NS_BINDING_REDIRECTED);
+      for (auto& endpoint : mStreamFilterEndpoints) {
+        extensions::StreamFilterParent::Attach(channel, std::move(endpoint));
+      }
+
+      RefPtr<ParentChannelWrapper> wrapper =
+          new ParentChannelWrapper(channel, mListener);
+
+      wrapper->Register(mDocumentLoadListener->GetRedirectChannelId());
+    }
+  }
+
+  mPromise.Resolve(aResult, __func__);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP ParentProcessDocumentChannel::AsyncOpen(
+    nsIStreamListener* aListener) {
+  LOG(("ParentProcessDocumentChannel AsyncOpen [this=%p]", this));
+  auto docShell = RefPtr<nsDocShell>(GetDocShell());
+  MOZ_ASSERT(docShell);
+
+  bool isDocumentLoad = mLoadInfo->GetExternalContentPolicyType() !=
+                        ExtContentPolicy::TYPE_OBJECT;
+
+  mDocumentLoadListener = MakeRefPtr<DocumentLoadListener>(
+      docShell->GetBrowsingContext()->Canonical(), isDocumentLoad);
+  LOG(("Created PPDocumentChannel with listener=%p",
+       mDocumentLoadListener.get()));
+
+  // Add observers.
+  nsCOMPtr<nsIObserverService> observerService =
+      mozilla::services::GetObserverService();
+  if (observerService) {
+    MOZ_ALWAYS_SUCCEEDS(observerService->AddObserver(
+        this, NS_HTTP_ON_MODIFY_REQUEST_TOPIC, false));
+  }
+
+  gHttpHandler->OnOpeningDocumentRequest(this);
+
+  if (isDocumentLoad) {
+    // Return value of setting synced field should be checked. See bug 1656492.
+    Unused << GetDocShell()->GetBrowsingContext()->SetCurrentLoadIdentifier(
+        Some(mLoadState->GetLoadIdentifier()));
+  }
+
+  nsresult rv = NS_OK;
+  Maybe<dom::ClientInfo> initialClientInfo = mInitialClientInfo;
+
+  RefPtr<DocumentLoadListener::OpenPromise> promise;
+  if (isDocumentLoad) {
+    promise = mDocumentLoadListener->OpenDocument(
+        mLoadState, mCacheKey, Some(mChannelId), TimeStamp::Now(), mTiming,
+        std::move(initialClientInfo), Some(mUriModified), Some(mIsXFOError),
+        nullptr /* ContentParent */, &rv);
+  } else {
+    promise = mDocumentLoadListener->OpenObject(
+        mLoadState, mCacheKey, Some(mChannelId), TimeStamp::Now(), mTiming,
+        std::move(initialClientInfo), InnerWindowIDForExtantDoc(docShell),
+        mLoadFlags, mLoadInfo->InternalContentPolicyType(),
+        dom::UserActivation::IsHandlingUserInput(), nullptr /* ContentParent */,
+        nullptr /* ObjectUpgradeHandler */, &rv);
+  }
+
+  if (NS_FAILED(rv)) {
+    MOZ_ASSERT(!promise);
+    mDocumentLoadListener = nullptr;
+    RemoveObserver();
+    return rv;
+  }
+
+  mListener = aListener;
+  if (mLoadGroup) {
+    mLoadGroup->AddRequest(this, nullptr);
+  }
+
+  RefPtr<ParentProcessDocumentChannel> self = this;
+  promise->Then(
+      GetCurrentSerialEventTarget(), __func__,
+      [self](DocumentLoadListener::OpenPromiseSucceededType&& aResolveValue) {
+        self->mDocumentLoadListener->CancelEarlyHintPreloads();
+        nsTArray<EarlyHintConnectArgs> earlyHints;
+
+        // The DLL is waiting for us to resolve the
+        // RedirectToRealChannelPromise given as parameter.
+        RefPtr<RedirectToRealChannelPromise> p =
+            self->RedirectToRealChannel(
+                    std::move(aResolveValue.mStreamFilterEndpoints),
+                    aResolveValue.mRedirectFlags, aResolveValue.mLoadFlags,
+                    earlyHints)
+                ->Then(
+                    GetCurrentSerialEventTarget(), __func__,
+                    [self](RedirectToRealChannelPromise::ResolveOrRejectValue&&
+                               aValue) -> RefPtr<RedirectToRealChannelPromise> {
+                      MOZ_ASSERT(aValue.IsResolve());
+                      nsresult rv = aValue.ResolveValue();
+                      if (NS_FAILED(rv)) {
+                        self->DisconnectChildListeners(rv, rv);
+                      }
+                      self->mLoadGroup = nullptr;
+                      self->mListener = nullptr;
+                      self->mCallbacks = nullptr;
+                      self->RemoveObserver();
+                      auto p =
+                          MakeRefPtr<RedirectToRealChannelPromise::Private>(
+                              __func__);
+                      p->UseDirectTaskDispatch(__func__);
+                      p->ResolveOrReject(std::move(aValue), __func__);
+                      return p;
+                    });
+        // We chain the promise the DLL is waiting on to the one returned by
+        // RedirectToRealChannel. As soon as the promise returned is
+        // resolved or rejected, so will the DLL's promise.
+        p->ChainTo(aResolveValue.mPromise.forget(), __func__);
+      },
+      [self](DocumentLoadListener::OpenPromiseFailedType&& aRejectValue) {
+        // If this is a normal failure, then we want to disconnect our listeners
+        // and notify them of the failure. If this is a process switch, then we
+        // can just ignore it silently, and trust that the switch will shut down
+        // our docshell and cancel us when it's ready.
+        if (!aRejectValue.mContinueNavigating) {
+          self->DisconnectChildListeners(aRejectValue.mStatus,
+                                         aRejectValue.mLoadGroupStatus);
+        }
+        self->RemoveObserver();
+      });
+  return NS_OK;
+}
+
+NS_IMETHODIMP ParentProcessDocumentChannel::Cancel(nsresult aStatus) {
+  return CancelWithReason(aStatus, "ParentProcessDocumentChannel::Cancel"_ns);
+}
+
+NS_IMETHODIMP ParentProcessDocumentChannel::CancelWithReason(
+    nsresult aStatusCode, const nsACString& aReason) {
+  LOG(("ParentProcessDocumentChannel CancelWithReason [this=%p]", this));
+  if (mCanceled) {
+    return NS_OK;
+  }
+
+  mCanceled = true;
+  // This will force the DocumentListener to abort the promise if there's one
+  // pending.
+  mDocumentLoadListener->Cancel(aStatusCode, aReason);
+
+  return NS_OK;
+}
+
+void ParentProcessDocumentChannel::RemoveObserver() {
+  if (nsCOMPtr<nsIObserverService> observerService =
+          mozilla::services::GetObserverService()) {
+    observerService->RemoveObserver(this, NS_HTTP_ON_MODIFY_REQUEST_TOPIC);
+  }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// nsIObserver
+////////////////////////////////////////////////////////////////////////////////
+
+NS_IMETHODIMP
+ParentProcessDocumentChannel::Observe(nsISupports* aSubject, const char* aTopic,
+                                      const char16_t* aData) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (mRequestObserversCalled) {
+    // We have already emitted the event, we don't want to emit it again.
+    // We only care about forwarding the first NS_HTTP_ON_MODIFY_REQUEST_TOPIC
+    // encountered.
+    return NS_OK;
+  }
+  nsCOMPtr<nsIChannel> channel = do_QueryInterface(aSubject);
+  if (!channel || mDocumentLoadListener->GetChannel() != channel) {
+    // Not a channel we are interested with.
+    return NS_OK;
+  }
+  LOG(("DocumentChannelParent Observe [this=%p aChannel=%p]", this,
+       channel.get()));
+  if (!nsCRT::strcmp(aTopic, NS_HTTP_ON_MODIFY_REQUEST_TOPIC)) {
+    mRequestObserversCalled = true;
+    gHttpHandler->OnModifyDocumentRequest(this);
+  }
+
+  return NS_OK;
+}
+
+}  // namespace net
+}  // namespace mozilla
+
+#undef LOG
diff --git a/netwerk/ipc/ParentProcessDocumentChannel.h b/netwerk/ipc/ParentProcessDocumentChannel.h
new file mode 100644
index 0000000000..d10d9833ff
--- /dev/null
+++ b/netwerk/ipc/ParentProcessDocumentChannel.h
@@ -0,0 +1,61 @@
+/* vim: set sw=2 ts=8 et tw=80 : */
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_ParentProcessDocumentChannel_h
+#define mozilla_net_ParentProcessDocumentChannel_h
+
+#include "mozilla/ipc/ProtocolUtils.h"
+#include "mozilla/net/DocumentChannel.h"
+#include "mozilla/net/DocumentLoadListener.h"
+#include "nsIObserver.h"
+#include "nsIAsyncVerifyRedirectCallback.h"
+
+namespace mozilla {
+namespace net {
+
+class EarlyHintConnectArgs;
+
+class ParentProcessDocumentChannel : public DocumentChannel,
+                                     public nsIAsyncVerifyRedirectCallback,
+                                     public nsIObserver {
+ public:
+  ParentProcessDocumentChannel(nsDocShellLoadState* aLoadState,
+                               class LoadInfo* aLoadInfo,
+                               nsLoadFlags aLoadFlags, uint32_t aCacheKey,
+                               bool aUriModified, bool aIsXFOError);
+
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_NSIASYNCVERIFYREDIRECTCALLBACK
+  NS_DECL_NSIOBSERVER
+
+  NS_IMETHOD AsyncOpen(nsIStreamListener* aListener) override;
+  NS_IMETHOD Cancel(nsresult aStatusCode) override;
+  NS_IMETHOD CancelWithReason(nsresult aStatusCode,
+                              const nsACString& aReason) override;
+
+  RefPtr<PDocumentChannelParent::RedirectToRealChannelPromise>
+  RedirectToRealChannel(
+      nsTArray<ipc::Endpoint<extensions::PStreamFilterParent>>&&
+          aStreamFilterEndpoints,
+      uint32_t aRedirectFlags, uint32_t aLoadFlags,
+      const nsTArray<EarlyHintConnectArgs>& aEarlyHints);
+
+ private:
+  virtual ~ParentProcessDocumentChannel();
+  void RemoveObserver();
+
+  RefPtr<DocumentLoadListener> mDocumentLoadListener;
+  nsTArray<ipc::Endpoint<extensions::PStreamFilterParent>>
+      mStreamFilterEndpoints;
+  MozPromiseHolder<PDocumentChannelParent::RedirectToRealChannelPromise>
+      mPromise;
+  bool mRequestObserversCalled = false;
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_net_ParentProcessDocumentChannel_h
diff --git a/netwerk/ipc/ProxyAutoConfigChild.cpp b/netwerk/ipc/ProxyAutoConfigChild.cpp
new file mode 100644
index 0000000000..1ab78c65e3
--- /dev/null
+++ b/netwerk/ipc/ProxyAutoConfigChild.cpp
@@ -0,0 +1,225 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ProxyAutoConfigChild.h"
+
+#include "mozilla/ipc/Endpoint.h"
+#include "mozilla/net/SocketProcessChild.h"
+#include "mozilla/SpinEventLoopUntil.h"
+#include "nsIObserver.h"
+#include "nsIObserverService.h"
+#include "nsThreadUtils.h"
+#include "ProxyAutoConfig.h"
+
+namespace mozilla::net {
+
+static bool sThreadLocalSetup = false;
+static uint32_t sThreadLocalIndex = 0xdeadbeef;
+StaticRefPtr<nsIThread> ProxyAutoConfigChild::sPACThread;
+bool ProxyAutoConfigChild::sShutdownObserverRegistered = false;
+static StaticRefPtr<ProxyAutoConfigChild> sActor;
+
+namespace {
+
+class ShutdownObserver final : public nsIObserver {
+ public:
+  ShutdownObserver() = default;
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+
+ private:
+  ~ShutdownObserver() = default;
+};
+
+NS_IMPL_ISUPPORTS(ShutdownObserver, nsIObserver)
+
+NS_IMETHODIMP
+ShutdownObserver::Observe(nsISupports* aSubject, const char* aTopic,
+                          const char16_t* aData) {
+  ProxyAutoConfigChild::ShutdownPACThread();
+  return NS_OK;
+}
+
+}  // namespace
+
+// static
+void ProxyAutoConfigChild::BindProxyAutoConfigChild(
+    RefPtr<ProxyAutoConfigChild>&& aActor,
+    Endpoint<PProxyAutoConfigChild>&& aEndpoint) {
+  // We only allow one ProxyAutoConfigChild at a time, so we need to
+  // wait until the old one to be destroyed.
+  if (sActor) {
+    NS_DispatchToCurrentThread(NS_NewRunnableFunction(
+        "BindProxyAutoConfigChild",
+        [actor = std::move(aActor), endpoint = std::move(aEndpoint)]() mutable {
+          ProxyAutoConfigChild::BindProxyAutoConfigChild(std::move(actor),
+                                                         std::move(endpoint));
+        }));
+    return;
+  }
+
+  if (aEndpoint.Bind(aActor)) {
+    sActor = aActor;
+  }
+}
+
+// static
+bool ProxyAutoConfigChild::Create(Endpoint<PProxyAutoConfigChild>&& aEndpoint) {
+  if (!sPACThread && !CreatePACThread()) {
+    NS_WARNING("Failed to create pac thread!");
+    return false;
+  }
+
+  if (!sShutdownObserverRegistered) {
+    nsCOMPtr<nsIObserverService> obs = services::GetObserverService();
+    if (NS_WARN_IF(!obs)) {
+      return false;
+    }
+    nsCOMPtr<nsIObserver> observer = new ShutdownObserver();
+    nsresult rv = obs->AddObserver(observer, "xpcom-shutdown-threads", false);
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      return false;
+    }
+    sShutdownObserverRegistered = true;
+  }
+
+  RefPtr<ProxyAutoConfigChild> actor = new ProxyAutoConfigChild();
+  if (NS_FAILED(sPACThread->Dispatch(NS_NewRunnableFunction(
+          "ProxyAutoConfigChild::ProxyAutoConfigChild",
+          [actor = std::move(actor),
+           endpoint = std::move(aEndpoint)]() mutable {
+            MOZ_ASSERT(endpoint.IsValid());
+            ProxyAutoConfigChild::BindProxyAutoConfigChild(std::move(actor),
+                                                           std::move(endpoint));
+          })))) {
+    NS_WARNING("Failed to dispatch runnable!");
+    return false;
+  }
+
+  return true;
+}
+
+// static
+bool ProxyAutoConfigChild::CreatePACThread() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (SocketProcessChild::GetSingleton()->IsShuttingDown()) {
+    NS_WARNING("Trying to create pac thread after shutdown has already begun!");
+    return false;
+  }
+
+  nsCOMPtr<nsIThread> thread;
+  if (NS_FAILED(NS_NewNamedThread("ProxyResolution", getter_AddRefs(thread)))) {
+    NS_WARNING("NS_NewNamedThread failed!");
+    return false;
+  }
+
+  sPACThread = thread.forget();
+  return true;
+}
+
+// static
+void ProxyAutoConfigChild::ShutdownPACThread() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (sPACThread) {
+    // Wait until all actos are released.
+    SpinEventLoopUntil("ProxyAutoConfigChild::ShutdownPACThread"_ns,
+                       [&]() { return !sActor; });
+
+    nsCOMPtr<nsIThread> thread = sPACThread.get();
+    sPACThread = nullptr;
+    MOZ_ALWAYS_SUCCEEDS(thread->Shutdown());
+  }
+}
+
+ProxyAutoConfigChild::ProxyAutoConfigChild()
+    : mPAC(MakeUnique<ProxyAutoConfig>()) {
+  if (!sThreadLocalSetup) {
+    sThreadLocalSetup = true;
+    PR_NewThreadPrivateIndex(&sThreadLocalIndex, nullptr);
+  }
+
+  mPAC->SetThreadLocalIndex(sThreadLocalIndex);
+}
+
+ProxyAutoConfigChild::~ProxyAutoConfigChild() = default;
+
+mozilla::ipc::IPCResult ProxyAutoConfigChild::RecvConfigurePAC(
+    const nsACString& aPACURI, const nsACString& aPACScriptData,
+    const bool& aIncludePath, const uint32_t& aExtraHeapSize) {
+  mPAC->ConfigurePAC(aPACURI, aPACScriptData, aIncludePath, aExtraHeapSize,
+                     GetMainThreadSerialEventTarget());
+  mPACLoaded = true;
+  NS_DispatchToCurrentThread(
+      NewRunnableMethod("ProxyAutoConfigChild::ProcessPendingQ", this,
+                        &ProxyAutoConfigChild::ProcessPendingQ));
+  return IPC_OK();
+}
+
+void ProxyAutoConfigChild::PendingQuery::Resolve(nsresult aStatus,
+                                                 const nsACString& aResult) {
+  mResolver(std::tuple<const nsresult&, const nsACString&>(aStatus, aResult));
+}
+
+mozilla::ipc::IPCResult ProxyAutoConfigChild::RecvGetProxyForURI(
+    const nsACString& aTestURI, const nsACString& aTestHost,
+    GetProxyForURIResolver&& aResolver) {
+  mPendingQ.insertBack(
+      new PendingQuery(aTestURI, aTestHost, std::move(aResolver)));
+  ProcessPendingQ();
+  return IPC_OK();
+}
+
+void ProxyAutoConfigChild::ProcessPendingQ() {
+  while (ProcessPending()) {
+    ;
+  }
+
+  if (mShutdown) {
+    mPAC->Shutdown();
+  } else {
+    // do GC while the thread has nothing pending
+    mPAC->GC();
+  }
+}
+
+bool ProxyAutoConfigChild::ProcessPending() {
+  if (mPendingQ.isEmpty()) {
+    return false;
+  }
+
+  if (mInProgress || !mPACLoaded) {
+    return false;
+  }
+
+  if (mShutdown) {
+    return true;
+  }
+
+  mInProgress = true;
+  RefPtr<PendingQuery> query = mPendingQ.popFirst();
+  nsCString result;
+  nsresult rv = mPAC->GetProxyForURI(query->URI(), query->Host(), result);
+  query->Resolve(rv, result);
+  mInProgress = false;
+  return true;
+}
+
+void ProxyAutoConfigChild::ActorDestroy(ActorDestroyReason aWhy) {
+  mPendingQ.clear();
+  mShutdown = true;
+  mPAC->Shutdown();
+
+  // To avoid racing with the main thread, we need to dispatch
+  // ProxyAutoConfigChild::Destroy again.
+  MOZ_ALWAYS_SUCCEEDS(NS_DispatchToCurrentThread(NewNonOwningRunnableMethod(
+      "ProxyAutoConfigChild::Destroy", this, &ProxyAutoConfigChild::Destroy)));
+}
+
+void ProxyAutoConfigChild::Destroy() { sActor = nullptr; }
+
+}  // namespace mozilla::net
diff --git a/netwerk/ipc/ProxyAutoConfigChild.h b/netwerk/ipc/ProxyAutoConfigChild.h
new file mode 100644
index 0000000000..19d757d646
--- /dev/null
+++ b/netwerk/ipc/ProxyAutoConfigChild.h
@@ -0,0 +1,84 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* 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 ProxyAutoConfigChild_h__
+#define ProxyAutoConfigChild_h__
+
+#include "mozilla/LinkedList.h"
+#include "mozilla/net/PProxyAutoConfigChild.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/UniquePtr.h"
+
+namespace mozilla {
+namespace net {
+
+class ProxyAutoConfig;
+
+class ProxyAutoConfigChild final : public PProxyAutoConfigChild {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ProxyAutoConfigChild, final)
+
+  static bool Create(Endpoint<PProxyAutoConfigChild>&& aEndpoint);
+  static bool CreatePACThread();
+  static void ShutdownPACThread();
+
+  ProxyAutoConfigChild();
+
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+  mozilla::ipc::IPCResult RecvConfigurePAC(const nsACString& aPACURI,
+                                           const nsACString& aPACScriptData,
+                                           const bool& aIncludePath,
+                                           const uint32_t& aExtraHeapSize);
+  mozilla::ipc::IPCResult RecvGetProxyForURI(
+      const nsACString& aTestURI, const nsACString& aTestHost,
+      GetProxyForURIResolver&& aResolver);
+
+  void Destroy();
+
+ private:
+  virtual ~ProxyAutoConfigChild();
+  void ProcessPendingQ();
+  bool ProcessPending();
+  static void BindProxyAutoConfigChild(
+      RefPtr<ProxyAutoConfigChild>&& aActor,
+      Endpoint<PProxyAutoConfigChild>&& aEndpoint);
+
+  UniquePtr<ProxyAutoConfig> mPAC;
+  bool mInProgress{false};
+  bool mPACLoaded{false};
+  bool mShutdown{false};
+
+  class PendingQuery final : public LinkedListElement<RefPtr<PendingQuery>> {
+   public:
+    NS_INLINE_DECL_REFCOUNTING(PendingQuery)
+
+    explicit PendingQuery(const nsACString& aTestURI,
+                          const nsACString& aTestHost,
+                          GetProxyForURIResolver&& aResolver)
+        : mURI(aTestURI), mHost(aTestHost), mResolver(std::move(aResolver)) {}
+
+    void Resolve(nsresult aStatus, const nsACString& aResult);
+    const nsCString& URI() const { return mURI; }
+    const nsCString& Host() const { return mHost; }
+
+   private:
+    ~PendingQuery() = default;
+
+    nsCString mURI;
+    nsCString mHost;
+    GetProxyForURIResolver mResolver;
+  };
+
+  LinkedList<RefPtr<PendingQuery>> mPendingQ;
+
+  static StaticRefPtr<nsIThread> sPACThread;
+  static bool sShutdownObserverRegistered;
+  static Atomic<uint32_t> sLiveActorCount;
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // ProxyAutoConfigChild_h__
diff --git a/netwerk/ipc/ProxyAutoConfigParent.cpp b/netwerk/ipc/ProxyAutoConfigParent.cpp
new file mode 100644
index 0000000000..d0a8727ef1
--- /dev/null
+++ b/netwerk/ipc/ProxyAutoConfigParent.cpp
@@ -0,0 +1,21 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ProxyAutoConfigParent.h"
+
+#include "mozilla/ipc/Endpoint.h"
+
+namespace mozilla::net {
+
+ProxyAutoConfigParent::ProxyAutoConfigParent() = default;
+
+ProxyAutoConfigParent::~ProxyAutoConfigParent() = default;
+
+void ProxyAutoConfigParent::Init(Endpoint<PProxyAutoConfigParent>&& aEndpoint) {
+  DebugOnly<bool> ok = aEndpoint.Bind(this);
+  MOZ_ASSERT(ok);
+}
+
+}  // namespace mozilla::net
diff --git a/netwerk/ipc/ProxyAutoConfigParent.h b/netwerk/ipc/ProxyAutoConfigParent.h
new file mode 100644
index 0000000000..f65a0714f2
--- /dev/null
+++ b/netwerk/ipc/ProxyAutoConfigParent.h
@@ -0,0 +1,28 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* 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 ProxyAutoConfigParent_h__
+#define ProxyAutoConfigParent_h__
+
+#include "mozilla/net/PProxyAutoConfigParent.h"
+
+namespace mozilla {
+namespace net {
+
+class ProxyAutoConfigParent final : public PProxyAutoConfigParent {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ProxyAutoConfigParent, final)
+
+  ProxyAutoConfigParent();
+  void Init(Endpoint<PProxyAutoConfigParent>&& aEndpoint);
+
+ private:
+  virtual ~ProxyAutoConfigParent();
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // ProxyAutoConfigParent_h__
diff --git a/netwerk/ipc/ProxyConfigLookup.cpp b/netwerk/ipc/ProxyConfigLookup.cpp
new file mode 100644
index 0000000000..29ce74091d
--- /dev/null
+++ b/netwerk/ipc/ProxyConfigLookup.cpp
@@ -0,0 +1,99 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ProxyConfigLookup.h"
+#include "ProxyConfigLookupChild.h"
+#include "mozilla/Unused.h"
+#include "nsContentUtils.h"
+#include "nsICancelable.h"
+#include "nsIProtocolProxyService.h"
+#include "nsIProtocolProxyService2.h"
+#include "nsNetUtil.h"
+#include "nsThreadUtils.h"
+#include "nsIChannel.h"
+
+namespace mozilla {
+namespace net {
+
+// static
+nsresult ProxyConfigLookup::Create(
+    std::function<void(nsIProxyInfo*, nsresult)>&& aCallback, nsIURI* aURI,
+    uint32_t aProxyResolveFlags, nsICancelable** aLookupCancellable) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  RefPtr<ProxyConfigLookup> lookUp =
+      new ProxyConfigLookup(std::move(aCallback), aURI, aProxyResolveFlags);
+  return lookUp->DoProxyResolve(aLookupCancellable);
+}
+
+ProxyConfigLookup::ProxyConfigLookup(
+    std::function<void(nsIProxyInfo*, nsresult)>&& aCallback, nsIURI* aURI,
+    uint32_t aProxyResolveFlags)
+    : mCallback(std::move(aCallback)),
+      mURI(aURI),
+      mProxyResolveFlags(aProxyResolveFlags) {}
+
+ProxyConfigLookup::~ProxyConfigLookup() = default;
+
+nsresult ProxyConfigLookup::DoProxyResolve(nsICancelable** aLookupCancellable) {
+  if (!XRE_IsParentProcess()) {
+    RefPtr<ProxyConfigLookup> self = this;
+    bool result = ProxyConfigLookupChild::Create(
+        mURI, mProxyResolveFlags,
+        [self](nsIProxyInfo* aProxyinfo, nsresult aResult) {
+          self->OnProxyAvailable(nullptr, nullptr, aProxyinfo, aResult);
+        });
+    return result ? NS_OK : NS_ERROR_FAILURE;
+  }
+
+  nsresult rv;
+  nsCOMPtr<nsIChannel> channel;
+  rv = NS_NewChannel(getter_AddRefs(channel), mURI,
+                     nsContentUtils::GetSystemPrincipal(),
+                     nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_SEC_CONTEXT_IS_NULL,
+                     nsIContentPolicy::TYPE_OTHER);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  nsCOMPtr<nsIProtocolProxyService> pps =
+      do_GetService(NS_PROTOCOLPROXYSERVICE_CONTRACTID, &rv);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  // using the nsIProtocolProxyService2 allows a minor performance
+  // optimization, but if an add-on has only provided the original interface
+  // then it is ok to use that version.
+  nsCOMPtr<nsICancelable> proxyRequest;
+  nsCOMPtr<nsIProtocolProxyService2> pps2 = do_QueryInterface(pps);
+  if (pps2) {
+    rv = pps2->AsyncResolve2(channel, mProxyResolveFlags, this, nullptr,
+                             getter_AddRefs(proxyRequest));
+  } else {
+    rv = pps->AsyncResolve(channel, mProxyResolveFlags, this, nullptr,
+                           getter_AddRefs(proxyRequest));
+  }
+
+  if (aLookupCancellable) {
+    proxyRequest.forget(aLookupCancellable);
+  }
+
+  return rv;
+}
+
+NS_IMETHODIMP ProxyConfigLookup::OnProxyAvailable(nsICancelable* aRequest,
+                                                  nsIChannel* aChannel,
+                                                  nsIProxyInfo* aProxyinfo,
+                                                  nsresult aResult) {
+  mCallback(aProxyinfo, aResult);
+  return NS_OK;
+}
+
+NS_IMPL_ISUPPORTS(ProxyConfigLookup, nsIProtocolProxyCallback)
+
+}  // namespace net
+}  // namespace mozilla
diff --git a/netwerk/ipc/ProxyConfigLookup.h b/netwerk/ipc/ProxyConfigLookup.h
new file mode 100644
index 0000000000..edef151964
--- /dev/null
+++ b/netwerk/ipc/ProxyConfigLookup.h
@@ -0,0 +1,44 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_ProxyConfigLookup_h
+#define mozilla_net_ProxyConfigLookup_h
+
+#include <functional>
+#include "nsIProtocolProxyCallback.h"
+#include "nsCOMPtr.h"
+
+class nsIURI;
+
+namespace mozilla {
+namespace net {
+
+class ProxyConfigLookup final : public nsIProtocolProxyCallback {
+ public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIPROTOCOLPROXYCALLBACK
+
+  static nsresult Create(
+      std::function<void(nsIProxyInfo*, nsresult)>&& aCallback, nsIURI* aURI,
+      uint32_t aProxyResolveFlags,
+      nsICancelable** aLookupCancellable = nullptr);
+
+ private:
+  explicit ProxyConfigLookup(
+      std::function<void(nsIProxyInfo*, nsresult)>&& aCallback, nsIURI* aURI,
+      uint32_t aProxyResolveFlags);
+  virtual ~ProxyConfigLookup();
+  nsresult DoProxyResolve(nsICancelable** aLookupCancellable);
+
+  std::function<void(nsIProxyInfo*, nsresult)> mCallback;
+  nsCOMPtr<nsIURI> mURI;
+  uint32_t mProxyResolveFlags;
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_net_ProxyConfigLookup_h
diff --git a/netwerk/ipc/ProxyConfigLookupChild.cpp b/netwerk/ipc/ProxyConfigLookupChild.cpp
new file mode 100644
index 0000000000..913b8460c2
--- /dev/null
+++ b/netwerk/ipc/ProxyConfigLookupChild.cpp
@@ -0,0 +1,43 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ProxyConfigLookupChild.h"
+
+#include "mozilla/net/SocketProcessChild.h"
+#include "nsProxyInfo.h"
+
+namespace mozilla {
+namespace net {
+
+// static
+bool ProxyConfigLookupChild::Create(
+    nsIURI* aURI, uint32_t aProxyResolveFlags,
+    std::function<void(nsIProxyInfo*, nsresult)>&& aCallback) {
+  SocketProcessChild* socketChild = SocketProcessChild::GetSingleton();
+  if (!socketChild) {
+    return false;
+  }
+
+  RefPtr<ProxyConfigLookupChild> child =
+      new ProxyConfigLookupChild(std::move(aCallback));
+  return socketChild->SendPProxyConfigLookupConstructor(child, aURI,
+                                                        aProxyResolveFlags);
+}
+
+ProxyConfigLookupChild::ProxyConfigLookupChild(
+    std::function<void(nsIProxyInfo*, nsresult)>&& aCallback)
+    : mCallback(std::move(aCallback)) {}
+
+mozilla::ipc::IPCResult ProxyConfigLookupChild::Recv__delete__(
+    nsTArray<ProxyInfoCloneArgs>&& aProxyInfo, const nsresult& aResult) {
+  nsCOMPtr<nsIProxyInfo> proxyInfo =
+      nsProxyInfo::DeserializeProxyInfo(aProxyInfo);
+  mCallback(proxyInfo, aResult);
+  return IPC_OK();
+}
+
+}  // namespace net
+}  // namespace mozilla
diff --git a/netwerk/ipc/ProxyConfigLookupChild.h b/netwerk/ipc/ProxyConfigLookupChild.h
new file mode 100644
index 0000000000..0c64f2835e
--- /dev/null
+++ b/netwerk/ipc/ProxyConfigLookupChild.h
@@ -0,0 +1,39 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_ProxyConfigLookupChild_h
+#define mozilla_net_ProxyConfigLookupChild_h
+
+#include "mozilla/net/PProxyConfigLookupChild.h"
+#include <functional>
+
+class nsIProxyInfo;
+
+namespace mozilla {
+namespace net {
+
+class ProxyConfigLookupChild final : public PProxyConfigLookupChild {
+ public:
+  NS_INLINE_DECL_REFCOUNTING(ProxyConfigLookupChild, override)
+
+  static bool Create(nsIURI* aURI, uint32_t aProxyResolveFlags,
+                     std::function<void(nsIProxyInfo*, nsresult)>&& aCallback);
+
+  mozilla::ipc::IPCResult Recv__delete__(
+      nsTArray<ProxyInfoCloneArgs>&& aProxyInfo, const nsresult& aResult);
+
+ private:
+  explicit ProxyConfigLookupChild(
+      std::function<void(nsIProxyInfo*, nsresult)>&& aCallback);
+  virtual ~ProxyConfigLookupChild() = default;
+
+  std::function<void(nsIProxyInfo*, nsresult)> mCallback;
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_net_ProxyConfigLookupChild_h
diff --git a/netwerk/ipc/ProxyConfigLookupParent.cpp b/netwerk/ipc/ProxyConfigLookupParent.cpp
new file mode 100644
index 0000000000..597f43eef5
--- /dev/null
+++ b/netwerk/ipc/ProxyConfigLookupParent.cpp
@@ -0,0 +1,43 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ProxyConfigLookupParent.h"
+#include "ProxyConfigLookup.h"
+#include "mozilla/Unused.h"
+#include "nsProxyInfo.h"
+
+namespace mozilla {
+namespace net {
+
+ProxyConfigLookupParent::ProxyConfigLookupParent(nsIURI* aURI,
+                                                 uint32_t aProxyResolveFlags)
+    : mURI(aURI), mProxyResolveFlags(aProxyResolveFlags) {}
+
+ProxyConfigLookupParent::~ProxyConfigLookupParent() = default;
+
+void ProxyConfigLookupParent::DoProxyLookup() {
+  RefPtr<ProxyConfigLookupParent> self = this;
+  nsresult rv = ProxyConfigLookup::Create(
+      [self](nsIProxyInfo* aProxyInfo, nsresult aStatus) {
+        if (self->CanSend()) {
+          nsTArray<ProxyInfoCloneArgs> proxyInfoArray;
+          if (aProxyInfo && NS_SUCCEEDED(aStatus)) {
+            nsProxyInfo::SerializeProxyInfo(
+                static_cast<nsProxyInfo*>(aProxyInfo), proxyInfoArray);
+          }
+          Unused << Send__delete__(self, proxyInfoArray, aStatus);
+        }
+      },
+      mURI, mProxyResolveFlags);
+
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    nsTArray<ProxyInfoCloneArgs> emptyArray;
+    Unused << Send__delete__(self, emptyArray, rv);
+  }
+}
+
+}  // namespace net
+}  // namespace mozilla
diff --git a/netwerk/ipc/ProxyConfigLookupParent.h b/netwerk/ipc/ProxyConfigLookupParent.h
new file mode 100644
index 0000000000..6ce23866c2
--- /dev/null
+++ b/netwerk/ipc/ProxyConfigLookupParent.h
@@ -0,0 +1,35 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_ProxyConfigLookupParent_h
+#define mozilla_net_ProxyConfigLookupParent_h
+
+#include "mozilla/net/PProxyConfigLookupParent.h"
+
+class nsIURI;
+
+namespace mozilla {
+namespace net {
+
+class ProxyConfigLookupParent final : public PProxyConfigLookupParent {
+ public:
+  NS_INLINE_DECL_REFCOUNTING(ProxyConfigLookupParent, override)
+
+  explicit ProxyConfigLookupParent(nsIURI* aURI, uint32_t aProxyResolveFlags);
+
+  void DoProxyLookup();
+
+ private:
+  virtual ~ProxyConfigLookupParent();
+
+  nsCOMPtr<nsIURI> mURI;
+  uint32_t mProxyResolveFlags;
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_net_ProxyConfigLookupParent_h
diff --git a/netwerk/ipc/SocketProcessBridgeChild.cpp b/netwerk/ipc/SocketProcessBridgeChild.cpp
new file mode 100644
index 0000000000..ed4ae04a90
--- /dev/null
+++ b/netwerk/ipc/SocketProcessBridgeChild.cpp
@@ -0,0 +1,189 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "SocketProcessBridgeChild.h"
+#include "SocketProcessLogging.h"
+
+#include "mozilla/AppShutdown.h"
+#include "mozilla/dom/ContentChild.h"
+#include "mozilla/ipc/BackgroundChild.h"
+#include "mozilla/ipc/Endpoint.h"
+#include "mozilla/net/NeckoChild.h"
+#include "nsIObserverService.h"
+#include "nsThreadUtils.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/StaticPrefs_network.h"
+
+namespace mozilla {
+
+using dom::ContentChild;
+
+namespace net {
+
+StaticRefPtr<SocketProcessBridgeChild>
+    SocketProcessBridgeChild::sSocketProcessBridgeChild;
+
+NS_IMPL_ISUPPORTS(SocketProcessBridgeChild, nsIObserver)
+
+// static
+bool SocketProcessBridgeChild::Create(
+    Endpoint<PSocketProcessBridgeChild>&& aEndpoint) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  sSocketProcessBridgeChild = new SocketProcessBridgeChild();
+
+  if (!aEndpoint.Bind(sSocketProcessBridgeChild)) {
+    MOZ_ASSERT(false, "Bind failed!");
+    sSocketProcessBridgeChild = nullptr;
+    return false;
+  }
+
+  nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
+  if (os) {
+    os->AddObserver(sSocketProcessBridgeChild, "content-child-shutdown", false);
+  }
+
+  sSocketProcessBridgeChild->mSocketProcessPid = aEndpoint.OtherPid();
+
+  mozilla::ipc::BackgroundChild::InitSocketBridgeStarter(
+      sSocketProcessBridgeChild);
+  return true;
+}
+
+// static
+already_AddRefed<SocketProcessBridgeChild>
+SocketProcessBridgeChild::GetSingleton() {
+  RefPtr<SocketProcessBridgeChild> child = sSocketProcessBridgeChild;
+  return child.forget();
+}
+
+// static
+RefPtr<SocketProcessBridgeChild::GetPromise>
+SocketProcessBridgeChild::GetSocketProcessBridge() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!StaticPrefs::network_process_enabled()) {
+    return GetPromise::CreateAndReject(nsCString("Socket process disabled!"),
+                                       __func__);
+  }
+
+  if (!gNeckoChild) {
+    return GetPromise::CreateAndReject(nsCString("No NeckoChild!"), __func__);
+  }
+
+  // ContentChild is shutting down, we should not try to create
+  // SocketProcessBridgeChild.
+  ContentChild* content = ContentChild::GetSingleton();
+  if (!content || content->IsShuttingDown()) {
+    return GetPromise::CreateAndReject(
+        nsCString("ContentChild is shutting down."), __func__);
+  }
+
+  if (sSocketProcessBridgeChild) {
+    return GetPromise::CreateAndResolve(sSocketProcessBridgeChild, __func__);
+  }
+
+  return gNeckoChild->SendInitSocketProcessBridge()->Then(
+      GetMainThreadSerialEventTarget(), __func__,
+      [](NeckoChild::InitSocketProcessBridgePromise::ResolveOrRejectValue&&
+             aResult) {
+        ContentChild* content = ContentChild::GetSingleton();
+        if (!content || content->IsShuttingDown()) {
+          return GetPromise::CreateAndReject(
+              nsCString("ContentChild is shutting down."), __func__);
+        }
+        if (!sSocketProcessBridgeChild) {
+          if (aResult.IsReject()) {
+            return GetPromise::CreateAndReject(
+                nsCString("SendInitSocketProcessBridge failed"), __func__);
+          }
+
+          if (!aResult.ResolveValue().IsValid()) {
+            return GetPromise::CreateAndReject(
+                nsCString(
+                    "SendInitSocketProcessBridge resolved with an invalid "
+                    "endpoint!"),
+                __func__);
+          }
+
+          if (!SocketProcessBridgeChild::Create(
+                  std::move(aResult.ResolveValue()))) {
+            return GetPromise::CreateAndReject(
+                nsCString("SendInitSocketProcessBridge resolved with a valid "
+                          "endpoint, "
+                          "but SocketProcessBridgeChild::Create failed!"),
+                __func__);
+          }
+        }
+
+        return GetPromise::CreateAndResolve(sSocketProcessBridgeChild,
+                                            __func__);
+      });
+}
+
+SocketProcessBridgeChild::SocketProcessBridgeChild() : mShuttingDown(false) {
+  LOG(("CONSTRUCT SocketProcessBridgeChild::SocketProcessBridgeChild\n"));
+}
+
+SocketProcessBridgeChild::~SocketProcessBridgeChild() {
+  LOG(("DESTRUCT SocketProcessBridgeChild::SocketProcessBridgeChild\n"));
+}
+
+mozilla::ipc::IPCResult SocketProcessBridgeChild::RecvTest() {
+  LOG(("SocketProcessBridgeChild::RecvTest\n"));
+  return IPC_OK();
+}
+
+void SocketProcessBridgeChild::ActorDestroy(ActorDestroyReason aWhy) {
+  LOG(("SocketProcessBridgeChild::ActorDestroy\n"));
+  if (AbnormalShutdown == aWhy) {
+    if (gNeckoChild &&
+        !AppShutdown::IsInOrBeyond(ShutdownPhase::AppShutdownConfirmed)) {
+      // Let NeckoParent know that the socket process connections must be
+      // rebuilt.
+      gNeckoChild->SendResetSocketProcessBridge();
+    }
+
+    nsresult res;
+    nsCOMPtr<nsISerialEventTarget> mSTSThread =
+        do_GetService(NS_SOCKETTRANSPORTSERVICE_CONTRACTID, &res);
+    if (NS_SUCCEEDED(res) && mSTSThread) {
+      // This must be called off the main thread.  If we don't make this call
+      // ipc::BackgroundChild::GetOrCreateSocketActorForCurrentThread() will
+      // return the previous actor that is no longer able to send. This causes
+      // rebuilding the socket process connections to fail.
+      MOZ_ALWAYS_SUCCEEDS(mSTSThread->Dispatch(NS_NewRunnableFunction(
+          "net::SocketProcessBridgeChild::ActorDestroy",
+          []() { ipc::BackgroundChild::CloseForCurrentThread(); })));
+    }
+  }
+
+  nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
+  if (os) {
+    os->RemoveObserver(this, "content-child-shutdown");
+  }
+  GetCurrentSerialEventTarget()->Dispatch(
+      NewRunnableMethod("net::SocketProcessBridgeChild::DeferredDestroy", this,
+                        &SocketProcessBridgeChild::DeferredDestroy));
+  mShuttingDown = true;
+}
+
+NS_IMETHODIMP
+SocketProcessBridgeChild::Observe(nsISupports* aSubject, const char* aTopic,
+                                  const char16_t* aData) {
+  if (!strcmp(aTopic, "content-child-shutdown")) {
+    PSocketProcessBridgeChild::Close();
+  }
+  return NS_OK;
+}
+
+void SocketProcessBridgeChild::DeferredDestroy() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  sSocketProcessBridgeChild = nullptr;
+}
+
+}  // namespace net
+}  // namespace mozilla
diff --git a/netwerk/ipc/SocketProcessBridgeChild.h b/netwerk/ipc/SocketProcessBridgeChild.h
new file mode 100644
index 0000000000..8b1c1ad6cf
--- /dev/null
+++ b/netwerk/ipc/SocketProcessBridgeChild.h
@@ -0,0 +1,50 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_SocketProcessBridgeChild_h
+#define mozilla_net_SocketProcessBridgeChild_h
+
+#include <functional>
+#include "mozilla/net/PSocketProcessBridgeChild.h"
+#include "nsIObserver.h"
+
+namespace mozilla {
+namespace net {
+
+// The IPC actor implements PSocketProcessBridgeChild in content process.
+// This is allocated and kept alive by NeckoChild. When "content-child-shutdown"
+// topic is observed, this actor will be destroyed.
+class SocketProcessBridgeChild final : public PSocketProcessBridgeChild,
+                                       public nsIObserver {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+
+  static already_AddRefed<SocketProcessBridgeChild> GetSingleton();
+  using GetPromise =
+      MozPromise<RefPtr<SocketProcessBridgeChild>, nsCString, false>;
+  static RefPtr<GetPromise> GetSocketProcessBridge();
+
+  mozilla::ipc::IPCResult RecvTest();
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+  void DeferredDestroy();
+  bool IsShuttingDown() const { return mShuttingDown; };
+  ProcessId SocketProcessPid() const { return mSocketProcessPid; };
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(SocketProcessBridgeChild);
+  static bool Create(Endpoint<PSocketProcessBridgeChild>&& aEndpoint);
+  explicit SocketProcessBridgeChild();
+  virtual ~SocketProcessBridgeChild();
+
+  static StaticRefPtr<SocketProcessBridgeChild> sSocketProcessBridgeChild;
+  bool mShuttingDown;
+  ProcessId mSocketProcessPid;
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_net_SocketProcessBridgeChild_h
diff --git a/netwerk/ipc/SocketProcessBridgeParent.cpp b/netwerk/ipc/SocketProcessBridgeParent.cpp
new file mode 100644
index 0000000000..020d8c2f3b
--- /dev/null
+++ b/netwerk/ipc/SocketProcessBridgeParent.cpp
@@ -0,0 +1,65 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "SocketProcessBridgeParent.h"
+#include "SocketProcessLogging.h"
+
+#include "mozilla/ipc/BackgroundParent.h"
+#include "mozilla/ipc/Endpoint.h"
+#include "SocketProcessChild.h"
+
+namespace mozilla {
+namespace net {
+
+SocketProcessBridgeParent::SocketProcessBridgeParent(ProcessId aId)
+    : mId(aId), mClosed(false) {
+  LOG(
+      ("CONSTRUCT SocketProcessBridgeParent::SocketProcessBridgeParent "
+       "mId=%" PRIPID "\n",
+       mId));
+  MOZ_COUNT_CTOR(SocketProcessBridgeParent);
+}
+
+SocketProcessBridgeParent::~SocketProcessBridgeParent() {
+  LOG(
+      ("DESTRUCT SocketProcessBridgeParent::SocketProcessBridgeParent "
+       "mId=%" PRIPID "\n",
+       mId));
+  MOZ_COUNT_DTOR(SocketProcessBridgeParent);
+}
+
+mozilla::ipc::IPCResult SocketProcessBridgeParent::RecvTest() {
+  LOG(("SocketProcessBridgeParent::RecvTest\n"));
+  Unused << SendTest();
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessBridgeParent::RecvInitBackground(
+    Endpoint<PBackgroundStarterParent>&& aEndpoint) {
+  LOG(("SocketProcessBridgeParent::RecvInitBackground mId=%" PRIPID "\n", mId));
+  if (!ipc::BackgroundParent::AllocStarter(nullptr, std::move(aEndpoint))) {
+    return IPC_FAIL(this, "BackgroundParent::Alloc failed");
+  }
+
+  return IPC_OK();
+}
+
+void SocketProcessBridgeParent::ActorDestroy(ActorDestroyReason aWhy) {
+  LOG(("SocketProcessBridgeParent::ActorDestroy mId=%" PRIPID "\n", mId));
+
+  mClosed = true;
+  GetCurrentSerialEventTarget()->Dispatch(
+      NewRunnableMethod("net::SocketProcessBridgeParent::DeferredDestroy", this,
+                        &SocketProcessBridgeParent::DeferredDestroy));
+}
+
+void SocketProcessBridgeParent::DeferredDestroy() {
+  if (SocketProcessChild* child = SocketProcessChild::GetSingleton()) {
+    child->DestroySocketProcessBridgeParent(mId);
+  }
+}
+
+}  // namespace net
+}  // namespace mozilla
diff --git a/netwerk/ipc/SocketProcessBridgeParent.h b/netwerk/ipc/SocketProcessBridgeParent.h
new file mode 100644
index 0000000000..7dbedc5c4d
--- /dev/null
+++ b/netwerk/ipc/SocketProcessBridgeParent.h
@@ -0,0 +1,43 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_SocketProcessBridgeParent_h
+#define mozilla_net_SocketProcessBridgeParent_h
+
+#include "mozilla/net/PSocketProcessBridgeParent.h"
+
+namespace mozilla {
+namespace net {
+
+// The IPC actor implements PSocketProcessBridgeParent in socket process.
+// This is allocated and kept alive by SocketProcessChild. When |ActorDestroy|
+// is called, |SocketProcessChild::DestroySocketProcessBridgeParent| will be
+// called to destroy this actor.
+class SocketProcessBridgeParent final : public PSocketProcessBridgeParent {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(SocketProcessBridgeParent, final)
+
+  explicit SocketProcessBridgeParent(ProcessId aId);
+
+  mozilla::ipc::IPCResult RecvTest();
+  mozilla::ipc::IPCResult RecvInitBackground(
+      Endpoint<PBackgroundStarterParent>&& aEndpoint);
+
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+  void DeferredDestroy();
+
+  bool Closed() const { return mClosed; }
+
+ private:
+  ~SocketProcessBridgeParent();
+
+  ProcessId mId;
+  bool mClosed;
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_net_SocketProcessBridgeParent_h
diff --git a/netwerk/ipc/SocketProcessChild.cpp b/netwerk/ipc/SocketProcessChild.cpp
new file mode 100644
index 0000000000..54b2fc9db9
--- /dev/null
+++ b/netwerk/ipc/SocketProcessChild.cpp
@@ -0,0 +1,715 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "SocketProcessChild.h"
+#include "SocketProcessLogging.h"
+
+#include "base/task.h"
+#include "InputChannelThrottleQueueChild.h"
+#include "HttpInfo.h"
+#include "HttpTransactionChild.h"
+#include "HttpConnectionMgrChild.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/Components.h"
+#include "mozilla/dom/MemoryReportRequest.h"
+#include "mozilla/FOGIPC.h"
+#include "mozilla/glean/GleanMetrics.h"
+#include "mozilla/ipc/CrashReporterClient.h"
+#include "mozilla/ipc/BackgroundChild.h"
+#include "mozilla/ipc/BackgroundParent.h"
+#include "mozilla/ipc/ProcessChild.h"
+#include "mozilla/net/AltSvcTransactionChild.h"
+#include "mozilla/net/BackgroundDataBridgeParent.h"
+#include "mozilla/net/DNSRequestChild.h"
+#include "mozilla/net/DNSRequestParent.h"
+#include "mozilla/net/NativeDNSResolverOverrideChild.h"
+#include "mozilla/net/ProxyAutoConfigChild.h"
+#include "mozilla/net/TRRServiceChild.h"
+#include "mozilla/ipc/ProcessUtils.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/RemoteLazyInputStreamChild.h"
+#include "mozilla/StaticPrefs_network.h"
+#include "mozilla/Telemetry.h"
+#include "NetworkConnectivityService.h"
+#include "nsDebugImpl.h"
+#include "nsHttpConnectionInfo.h"
+#include "nsHttpHandler.h"
+#include "nsIDNSService.h"
+#include "nsIHttpActivityObserver.h"
+#include "nsIXULRuntime.h"
+#include "nsNetUtil.h"
+#include "nsNSSComponent.h"
+#include "nsSocketTransportService2.h"
+#include "nsThreadManager.h"
+#include "SocketProcessBridgeParent.h"
+#include "jsapi.h"
+#include "js/Initialization.h"
+#include "XPCSelfHostedShmem.h"
+
+#if defined(XP_WIN)
+#  include <process.h>
+
+#  include "mozilla/WinDllServices.h"
+#else
+#  include <unistd.h>
+#endif
+
+#if defined(XP_LINUX) && defined(MOZ_SANDBOX)
+#  include "mozilla/Sandbox.h"
+#endif
+
+#include "ChildProfilerController.h"
+
+#ifdef MOZ_WEBRTC
+#  include "mozilla/net/WebrtcTCPSocketChild.h"
+#endif
+
+#if defined(MOZ_SANDBOX) && defined(MOZ_DEBUG) && defined(ENABLE_TESTS)
+#  include "mozilla/SandboxTestingChild.h"
+#endif
+
+namespace mozilla {
+namespace net {
+
+using namespace ipc;
+
+static bool sInitializedJS = false;
+
+static Atomic<SocketProcessChild*> sSocketProcessChild;
+
+SocketProcessChild::SocketProcessChild() {
+  LOG(("CONSTRUCT SocketProcessChild::SocketProcessChild\n"));
+  nsDebugImpl::SetMultiprocessMode("Socket");
+
+  MOZ_COUNT_CTOR(SocketProcessChild);
+  sSocketProcessChild = this;
+}
+
+SocketProcessChild::~SocketProcessChild() {
+  LOG(("DESTRUCT SocketProcessChild::SocketProcessChild\n"));
+  MOZ_COUNT_DTOR(SocketProcessChild);
+  sSocketProcessChild = nullptr;
+}
+
+/* static */
+SocketProcessChild* SocketProcessChild::GetSingleton() {
+  return sSocketProcessChild;
+}
+
+#if defined(XP_MACOSX)
+extern "C" {
+void CGSShutdownServerConnections();
+};
+#endif
+
+bool SocketProcessChild::Init(mozilla::ipc::UntypedEndpoint&& aEndpoint,
+                              const char* aParentBuildID) {
+  if (NS_WARN_IF(NS_FAILED(nsThreadManager::get().Init()))) {
+    return false;
+  }
+  if (NS_WARN_IF(!aEndpoint.Bind(this))) {
+    return false;
+  }
+  // This must be sent before any IPDL message, which may hit sentinel
+  // errors due to parent and content processes having different
+  // versions.
+  MessageChannel* channel = GetIPCChannel();
+  if (channel && !channel->SendBuildIDsMatchMessage(aParentBuildID)) {
+    // We need to quit this process if the buildID doesn't match the parent's.
+    // This can occur when an update occurred in the background.
+    ProcessChild::QuickExit();
+  }
+
+  // Init crash reporter support.
+  CrashReporterClient::InitSingleton(this);
+
+  if (NS_FAILED(NS_InitMinimalXPCOM())) {
+    return false;
+  }
+
+  BackgroundChild::Startup();
+  BackgroundChild::InitSocketStarter(this);
+
+  SetThisProcessName("Socket Process");
+#if defined(XP_MACOSX)
+  // Close all current connections to the WindowServer. This ensures that the
+  // Activity Monitor will not label the socket process as "Not responding"
+  // because it's not running a native event loop. See bug 1384336.
+  CGSShutdownServerConnections();
+#endif  // XP_MACOSX
+
+  nsresult rv;
+  nsCOMPtr<nsIIOService> ios = do_GetIOService(&rv);
+  if (NS_FAILED(rv)) {
+    return false;
+  }
+
+  nsCOMPtr<nsIProtocolHandler> handler;
+  rv = ios->GetProtocolHandler("http", getter_AddRefs(handler));
+  if (NS_FAILED(rv)) {
+    return false;
+  }
+
+  // Initialize DNS Service here, since it needs to be done in main thread.
+  nsCOMPtr<nsIDNSService> dns =
+      do_GetService("@mozilla.org/network/dns-service;1", &rv);
+  if (NS_FAILED(rv)) {
+    return false;
+  }
+
+  if (!EnsureNSSInitializedChromeOrContent()) {
+    return false;
+  }
+
+  return true;
+}
+
+void SocketProcessChild::ActorDestroy(ActorDestroyReason aWhy) {
+  LOG(("SocketProcessChild::ActorDestroy\n"));
+
+  mShuttingDown = true;
+
+  if (AbnormalShutdown == aWhy) {
+    NS_WARNING("Shutting down Socket process early due to a crash!");
+    ProcessChild::QuickExit();
+  }
+
+  // Send the last bits of Glean data over to the main process.
+  glean::FlushFOGData(
+      [](ByteBuf&& aBuf) { glean::SendFOGData(std::move(aBuf)); });
+
+  if (mProfilerController) {
+    mProfilerController->Shutdown();
+    mProfilerController = nullptr;
+  }
+
+  CrashReporterClient::DestroySingleton();
+  XRE_ShutdownChildProcess();
+}
+
+void SocketProcessChild::CleanUp() {
+  LOG(("SocketProcessChild::CleanUp\n"));
+
+  for (const auto& parent : mSocketProcessBridgeParentMap.Values()) {
+    if (!parent->Closed()) {
+      parent->Close();
+    }
+  }
+
+  {
+    MutexAutoLock lock(mMutex);
+    mBackgroundDataBridgeMap.Clear();
+  }
+
+  // Normally, the IPC channel should be already closed at this point, but
+  // sometimes it's not (bug 1788860). When the channel is closed, calling
+  // Close() again is harmless.
+  Close();
+
+  NS_ShutdownXPCOM(nullptr);
+
+  if (sInitializedJS) {
+    JS_ShutDown();
+  }
+}
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvInit(
+    const SocketPorcessInitAttributes& aAttributes) {
+  Unused << RecvSetOffline(aAttributes.mOffline());
+  Unused << RecvSetConnectivity(aAttributes.mConnectivity());
+  if (aAttributes.mInitSandbox()) {
+    Unused << RecvInitLinuxSandbox(aAttributes.mSandboxBroker());
+  }
+
+#if defined(XP_WIN)
+  RefPtr<DllServices> dllSvc(DllServices::Get());
+  dllSvc->StartUntrustedModulesProcessor(
+      aAttributes.mIsReadyForBackgroundProcessing());
+#endif  // defined(XP_WIN)
+
+  return IPC_OK();
+}
+
+IPCResult SocketProcessChild::RecvPreferenceUpdate(const Pref& aPref) {
+  Preferences::SetPreference(aPref);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvRequestMemoryReport(
+    const uint32_t& aGeneration, const bool& aAnonymize,
+    const bool& aMinimizeMemoryUsage,
+    const Maybe<ipc::FileDescriptor>& aDMDFile,
+    const RequestMemoryReportResolver& aResolver) {
+  nsPrintfCString processName("Socket (pid %u)", (unsigned)getpid());
+
+  mozilla::dom::MemoryReportRequestClient::Start(
+      aGeneration, aAnonymize, aMinimizeMemoryUsage, aDMDFile, processName,
+      [&](const MemoryReport& aReport) {
+        Unused << GetSingleton()->SendAddMemoryReport(aReport);
+      },
+      aResolver);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvSetOffline(
+    const bool& aOffline) {
+  LOG(("SocketProcessChild::RecvSetOffline aOffline=%d\n", aOffline));
+
+  nsCOMPtr<nsIIOService> io(do_GetIOService());
+  NS_ASSERTION(io, "IO Service can not be null");
+
+  io->SetOffline(aOffline);
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvSetConnectivity(
+    const bool& aConnectivity) {
+  nsCOMPtr<nsIIOService> io(do_GetIOService());
+  nsCOMPtr<nsIIOServiceInternal> ioInternal(do_QueryInterface(io));
+  NS_ASSERTION(ioInternal, "IO Service can not be null");
+
+  ioInternal->SetConnectivity(aConnectivity);
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvInitLinuxSandbox(
+    const Maybe<ipc::FileDescriptor>& aBrokerFd) {
+#if defined(XP_LINUX) && defined(MOZ_SANDBOX)
+  int fd = -1;
+  if (aBrokerFd.isSome()) {
+    fd = aBrokerFd.value().ClonePlatformHandle().release();
+  }
+  SetSocketProcessSandbox(fd);
+#endif  // XP_LINUX && MOZ_SANDBOX
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvInitSocketProcessBridgeParent(
+    const ProcessId& aContentProcessId,
+    Endpoint<mozilla::net::PSocketProcessBridgeParent>&& aEndpoint) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!mSocketProcessBridgeParentMap.Contains(aContentProcessId));
+
+  if (NS_WARN_IF(!aEndpoint.IsValid())) {
+    return IPC_FAIL(this, "invalid endpoint");
+  }
+
+  auto bridge = MakeRefPtr<SocketProcessBridgeParent>(aContentProcessId);
+  MOZ_ALWAYS_TRUE(aEndpoint.Bind(bridge));
+
+  mSocketProcessBridgeParentMap.InsertOrUpdate(aContentProcessId,
+                                               std::move(bridge));
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvInitProfiler(
+    Endpoint<PProfilerChild>&& aEndpoint) {
+  mProfilerController =
+      mozilla::ChildProfilerController::Create(std::move(aEndpoint));
+  return IPC_OK();
+}
+
+#if defined(MOZ_SANDBOX) && defined(MOZ_DEBUG) && defined(ENABLE_TESTS)
+mozilla::ipc::IPCResult SocketProcessChild::RecvInitSandboxTesting(
+    Endpoint<PSandboxTestingChild>&& aEndpoint) {
+  if (!SandboxTestingChild::Initialize(std::move(aEndpoint))) {
+    return IPC_FAIL(
+        this, "InitSandboxTesting failed to initialise the child process.");
+  }
+  return IPC_OK();
+}
+#endif
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvSocketProcessTelemetryPing() {
+  const uint32_t kExpectedUintValue = 42;
+  Telemetry::ScalarSet(Telemetry::ScalarID::TELEMETRY_TEST_SOCKET_ONLY_UINT,
+                       kExpectedUintValue);
+  return IPC_OK();
+}
+
+void SocketProcessChild::DestroySocketProcessBridgeParent(ProcessId aId) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  mSocketProcessBridgeParentMap.Remove(aId);
+}
+
+PWebrtcTCPSocketChild* SocketProcessChild::AllocPWebrtcTCPSocketChild(
+    const Maybe<TabId>& tabId) {
+  // We don't allocate here: instead we always use IPDL constructor that takes
+  // an existing object
+  MOZ_ASSERT_UNREACHABLE(
+      "AllocPWebrtcTCPSocketChild should not be called on"
+      " socket child");
+  return nullptr;
+}
+
+bool SocketProcessChild::DeallocPWebrtcTCPSocketChild(
+    PWebrtcTCPSocketChild* aActor) {
+#ifdef MOZ_WEBRTC
+  WebrtcTCPSocketChild* child = static_cast<WebrtcTCPSocketChild*>(aActor);
+  child->ReleaseIPDLReference();
+#endif
+  return true;
+}
+
+already_AddRefed<PHttpTransactionChild>
+SocketProcessChild::AllocPHttpTransactionChild() {
+  RefPtr<HttpTransactionChild> actor = new HttpTransactionChild();
+  return actor.forget();
+}
+
+already_AddRefed<PHttpConnectionMgrChild>
+SocketProcessChild::AllocPHttpConnectionMgrChild(
+    const HttpHandlerInitArgs& aArgs) {
+  LOG(("SocketProcessChild::AllocPHttpConnectionMgrChild \n"));
+  MOZ_ASSERT(gHttpHandler);
+  gHttpHandler->SetHttpHandlerInitArgs(aArgs);
+
+  RefPtr<HttpConnectionMgrChild> actor = new HttpConnectionMgrChild();
+  return actor.forget();
+}
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvUpdateDeviceModelId(
+    const nsACString& aModelId) {
+  MOZ_ASSERT(gHttpHandler);
+  gHttpHandler->SetDeviceModelId(aModelId);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult
+SocketProcessChild::RecvOnHttpActivityDistributorActivated(
+    const bool& aIsActivated) {
+  if (nsCOMPtr<nsIHttpActivityObserver> distributor =
+          components::HttpActivityDistributor::Service()) {
+    distributor->SetIsActive(aIsActivated);
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult
+SocketProcessChild::RecvOnHttpActivityDistributorObserveProxyResponse(
+    const bool& aIsEnabled) {
+  nsCOMPtr<nsIHttpActivityDistributor> distributor =
+      do_GetService("@mozilla.org/network/http-activity-distributor;1");
+  if (distributor) {
+    Unused << distributor->SetObserveProxyResponse(aIsEnabled);
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult
+SocketProcessChild::RecvOnHttpActivityDistributorObserveConnection(
+    const bool& aIsEnabled) {
+  nsCOMPtr<nsIHttpActivityDistributor> distributor =
+      do_GetService("@mozilla.org/network/http-activity-distributor;1");
+  if (distributor) {
+    Unused << distributor->SetObserveConnection(aIsEnabled);
+  }
+  return IPC_OK();
+}
+
+already_AddRefed<PInputChannelThrottleQueueChild>
+SocketProcessChild::AllocPInputChannelThrottleQueueChild(
+    const uint32_t& aMeanBytesPerSecond, const uint32_t& aMaxBytesPerSecond) {
+  RefPtr<InputChannelThrottleQueueChild> p =
+      new InputChannelThrottleQueueChild();
+  p->Init(aMeanBytesPerSecond, aMaxBytesPerSecond);
+  return p.forget();
+}
+
+already_AddRefed<PAltSvcTransactionChild>
+SocketProcessChild::AllocPAltSvcTransactionChild(
+    const HttpConnectionInfoCloneArgs& aConnInfo, const uint32_t& aCaps) {
+  RefPtr<nsHttpConnectionInfo> cinfo =
+      nsHttpConnectionInfo::DeserializeHttpConnectionInfoCloneArgs(aConnInfo);
+  RefPtr<AltSvcTransactionChild> child =
+      new AltSvcTransactionChild(cinfo, aCaps);
+  return child.forget();
+}
+
+already_AddRefed<PDNSRequestChild> SocketProcessChild::AllocPDNSRequestChild(
+    const nsACString& aHost, const nsACString& aTrrServer, const int32_t& aPort,
+    const uint16_t& aType, const OriginAttributes& aOriginAttributes,
+    const nsIDNSService::DNSFlags& aFlags) {
+  RefPtr<DNSRequestHandler> handler = new DNSRequestHandler();
+  RefPtr<DNSRequestChild> actor = new DNSRequestChild(handler);
+  return actor.forget();
+}
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvPDNSRequestConstructor(
+    PDNSRequestChild* aActor, const nsACString& aHost,
+    const nsACString& aTrrServer, const int32_t& aPort, const uint16_t& aType,
+    const OriginAttributes& aOriginAttributes,
+    const nsIDNSService::DNSFlags& aFlags) {
+  RefPtr<DNSRequestChild> actor = static_cast<DNSRequestChild*>(aActor);
+  RefPtr<DNSRequestHandler> handler =
+      actor->GetDNSRequest()->AsDNSRequestHandler();
+  handler->DoAsyncResolve(aHost, aTrrServer, aPort, aType, aOriginAttributes,
+                          aFlags);
+  return IPC_OK();
+}
+
+void SocketProcessChild::AddDataBridgeToMap(
+    uint64_t aChannelId, BackgroundDataBridgeParent* aActor) {
+  ipc::AssertIsOnBackgroundThread();
+  MutexAutoLock lock(mMutex);
+  mBackgroundDataBridgeMap.InsertOrUpdate(aChannelId, RefPtr{aActor});
+}
+
+void SocketProcessChild::RemoveDataBridgeFromMap(uint64_t aChannelId) {
+  ipc::AssertIsOnBackgroundThread();
+  MutexAutoLock lock(mMutex);
+  mBackgroundDataBridgeMap.Remove(aChannelId);
+}
+
+Maybe<RefPtr<BackgroundDataBridgeParent>>
+SocketProcessChild::GetAndRemoveDataBridge(uint64_t aChannelId) {
+  MutexAutoLock lock(mMutex);
+  return mBackgroundDataBridgeMap.Extract(aChannelId);
+}
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvClearSessionCache(
+    ClearSessionCacheResolver&& aResolve) {
+  nsNSSComponent::DoClearSSLExternalAndInternalSessionCache();
+  aResolve(void_t{});
+  return IPC_OK();
+}
+
+already_AddRefed<PTRRServiceChild> SocketProcessChild::AllocPTRRServiceChild(
+    const bool& aCaptiveIsPassed, const bool& aParentalControlEnabled,
+    const nsTArray<nsCString>& aDNSSuffixList) {
+  RefPtr<TRRServiceChild> actor = new TRRServiceChild();
+  return actor.forget();
+}
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvPTRRServiceConstructor(
+    PTRRServiceChild* aActor, const bool& aCaptiveIsPassed,
+    const bool& aParentalControlEnabled, nsTArray<nsCString>&& aDNSSuffixList) {
+  static_cast<TRRServiceChild*>(aActor)->Init(
+      aCaptiveIsPassed, aParentalControlEnabled, std::move(aDNSSuffixList));
+  return IPC_OK();
+}
+
+already_AddRefed<PNativeDNSResolverOverrideChild>
+SocketProcessChild::AllocPNativeDNSResolverOverrideChild() {
+  RefPtr<NativeDNSResolverOverrideChild> actor =
+      new NativeDNSResolverOverrideChild();
+  return actor.forget();
+}
+
+mozilla::ipc::IPCResult
+SocketProcessChild::RecvPNativeDNSResolverOverrideConstructor(
+    PNativeDNSResolverOverrideChild* aActor) {
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvNotifyObserver(
+    const nsACString& aTopic, const nsAString& aData) {
+  if (nsCOMPtr<nsIObserverService> obs =
+          mozilla::services::GetObserverService()) {
+    obs->NotifyObservers(nullptr, PromiseFlatCString(aTopic).get(),
+                         PromiseFlatString(aData).get());
+  }
+  return IPC_OK();
+}
+
+namespace {
+
+class DataResolverBase {
+ public:
+  // This type is threadsafe-refcounted, as it's referenced on the socket
+  // thread, but must be destroyed on the main thread.
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING_WITH_DELETE_ON_MAIN_THREAD(
+      DataResolverBase)
+
+  DataResolverBase() = default;
+
+ protected:
+  virtual ~DataResolverBase() = default;
+};
+
+template <typename DataType, typename ResolverType>
+class DataResolver final : public DataResolverBase {
+ public:
+  explicit DataResolver(ResolverType&& aResolve)
+      : mResolve(std::move(aResolve)) {}
+
+  void OnResolve(DataType&& aData) {
+    MOZ_ASSERT(OnSocketThread());
+
+    RefPtr<DataResolver<DataType, ResolverType>> self = this;
+    mData = std::move(aData);
+    NS_DispatchToMainThread(NS_NewRunnableFunction(
+        "net::DataResolver::OnResolve",
+        [self{std::move(self)}]() { self->mResolve(std::move(self->mData)); }));
+  }
+
+ private:
+  virtual ~DataResolver() = default;
+
+  ResolverType mResolve;
+  DataType mData;
+};
+
+}  // anonymous namespace
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvGetSocketData(
+    GetSocketDataResolver&& aResolve) {
+  if (!gSocketTransportService) {
+    aResolve(SocketDataArgs());
+    return IPC_OK();
+  }
+
+  RefPtr<
+      DataResolver<SocketDataArgs, SocketProcessChild::GetSocketDataResolver>>
+      resolver = new DataResolver<SocketDataArgs,
+                                  SocketProcessChild::GetSocketDataResolver>(
+          std::move(aResolve));
+  gSocketTransportService->Dispatch(
+      NS_NewRunnableFunction(
+          "net::SocketProcessChild::RecvGetSocketData",
+          [resolver{std::move(resolver)}]() {
+            SocketDataArgs args;
+            gSocketTransportService->GetSocketConnections(&args.info());
+            args.totalSent() = gSocketTransportService->GetSentBytes();
+            args.totalRecv() = gSocketTransportService->GetReceivedBytes();
+            resolver->OnResolve(std::move(args));
+          }),
+      NS_DISPATCH_NORMAL);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvGetDNSCacheEntries(
+    GetDNSCacheEntriesResolver&& aResolve) {
+  nsresult rv = NS_OK;
+  nsCOMPtr<nsIDNSService> dns =
+      do_GetService("@mozilla.org/network/dns-service;1", &rv);
+  if (NS_FAILED(rv)) {
+    aResolve(nsTArray<DNSCacheEntries>());
+    return IPC_OK();
+  }
+
+  RefPtr<DataResolver<nsTArray<DNSCacheEntries>,
+                      SocketProcessChild::GetDNSCacheEntriesResolver>>
+      resolver =
+          new DataResolver<nsTArray<DNSCacheEntries>,
+                           SocketProcessChild::GetDNSCacheEntriesResolver>(
+              std::move(aResolve));
+  gSocketTransportService->Dispatch(
+      NS_NewRunnableFunction(
+          "net::SocketProcessChild::RecvGetDNSCacheEntries",
+          [resolver{std::move(resolver)}, dns{std::move(dns)}]() {
+            nsTArray<DNSCacheEntries> entries;
+            dns->GetDNSCacheEntries(&entries);
+            resolver->OnResolve(std::move(entries));
+          }),
+      NS_DISPATCH_NORMAL);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvGetHttpConnectionData(
+    GetHttpConnectionDataResolver&& aResolve) {
+  if (!gSocketTransportService) {
+    aResolve(nsTArray<HttpRetParams>());
+    return IPC_OK();
+  }
+
+  RefPtr<DataResolver<nsTArray<HttpRetParams>,
+                      SocketProcessChild::GetHttpConnectionDataResolver>>
+      resolver =
+          new DataResolver<nsTArray<HttpRetParams>,
+                           SocketProcessChild::GetHttpConnectionDataResolver>(
+              std::move(aResolve));
+  gSocketTransportService->Dispatch(
+      NS_NewRunnableFunction(
+          "net::SocketProcessChild::RecvGetHttpConnectionData",
+          [resolver{std::move(resolver)}]() {
+            nsTArray<HttpRetParams> data;
+            HttpInfo::GetHttpConnectionData(&data);
+            resolver->OnResolve(std::move(data));
+          }),
+      NS_DISPATCH_NORMAL);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvInitProxyAutoConfigChild(
+    Endpoint<PProxyAutoConfigChild>&& aEndpoint) {
+  // For parsing PAC.
+  if (!sInitializedJS) {
+    JS::DisableJitBackend();
+
+    const char* jsInitFailureReason = JS_InitWithFailureDiagnostic();
+    if (jsInitFailureReason) {
+      MOZ_CRASH_UNSAFE(jsInitFailureReason);
+    }
+    sInitializedJS = true;
+
+    xpc::SelfHostedShmem::GetSingleton();
+  }
+
+  Unused << ProxyAutoConfigChild::Create(std::move(aEndpoint));
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvRecheckIPConnectivity() {
+  RefPtr<NetworkConnectivityService> ncs =
+      NetworkConnectivityService::GetSingleton();
+  if (ncs) {
+    ncs->RecheckIPConnectivity();
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvRecheckDNS() {
+  RefPtr<NetworkConnectivityService> ncs =
+      NetworkConnectivityService::GetSingleton();
+  if (ncs) {
+    ncs->RecheckDNS();
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvFlushFOGData(
+    FlushFOGDataResolver&& aResolver) {
+  glean::FlushFOGData(std::move(aResolver));
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessChild::RecvTestTriggerMetrics(
+    TestTriggerMetricsResolver&& aResolve) {
+  mozilla::glean::test_only_ipc::a_counter.Add(
+      nsIXULRuntime::PROCESS_TYPE_SOCKET);
+  aResolve(true);
+  return IPC_OK();
+}
+
+#if defined(XP_WIN)
+mozilla::ipc::IPCResult SocketProcessChild::RecvGetUntrustedModulesData(
+    GetUntrustedModulesDataResolver&& aResolver) {
+  RefPtr<DllServices> dllSvc(DllServices::Get());
+  dllSvc->GetUntrustedModulesData()->Then(
+      GetMainThreadSerialEventTarget(), __func__,
+      [aResolver](Maybe<UntrustedModulesData>&& aData) {
+        aResolver(std::move(aData));
+      },
+      [aResolver](nsresult aReason) { aResolver(Nothing()); });
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult
+SocketProcessChild::RecvUnblockUntrustedModulesThread() {
+  if (nsCOMPtr<nsIObserverService> obs =
+          mozilla::services::GetObserverService()) {
+    obs->NotifyObservers(nullptr, "unblock-untrusted-modules-thread", nullptr);
+  }
+  return IPC_OK();
+}
+#endif  // defined(XP_WIN)
+
+}  // namespace net
+}  // namespace mozilla
diff --git a/netwerk/ipc/SocketProcessChild.h b/netwerk/ipc/SocketProcessChild.h
new file mode 100644
index 0000000000..d652b86cdb
--- /dev/null
+++ b/netwerk/ipc/SocketProcessChild.h
@@ -0,0 +1,172 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_SocketProcessChild_h
+#define mozilla_net_SocketProcessChild_h
+
+#include "mozilla/net/PSocketProcessChild.h"
+#include "mozilla/ipc/InputStreamUtils.h"
+#include "mozilla/Mutex.h"
+#include "nsRefPtrHashtable.h"
+#include "nsTHashMap.h"
+
+namespace mozilla {
+class ChildProfilerController;
+}
+
+namespace mozilla {
+namespace net {
+
+class ProxyAutoConfigChild;
+class SocketProcessBridgeParent;
+class BackgroundDataBridgeParent;
+
+// The IPC actor implements PSocketProcessChild in child process.
+// This is allocated and kept alive by SocketProcessImpl.
+class SocketProcessChild final : public PSocketProcessChild {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(SocketProcessChild, final)
+
+  SocketProcessChild();
+
+  static SocketProcessChild* GetSingleton();
+
+  bool Init(mozilla::ipc::UntypedEndpoint&& aEndpoint,
+            const char* aParentBuildID);
+
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+
+  mozilla::ipc::IPCResult RecvInit(
+      const SocketPorcessInitAttributes& aAttributes);
+  mozilla::ipc::IPCResult RecvPreferenceUpdate(const Pref& aPref);
+  mozilla::ipc::IPCResult RecvRequestMemoryReport(
+      const uint32_t& generation, const bool& anonymize,
+      const bool& minimizeMemoryUsage,
+      const Maybe<mozilla::ipc::FileDescriptor>& DMDFile,
+      const RequestMemoryReportResolver& aResolver);
+  mozilla::ipc::IPCResult RecvSetOffline(const bool& aOffline);
+  mozilla::ipc::IPCResult RecvSetConnectivity(const bool& aConnectivity);
+  mozilla::ipc::IPCResult RecvInitLinuxSandbox(
+      const Maybe<ipc::FileDescriptor>& aBrokerFd);
+  mozilla::ipc::IPCResult RecvInitSocketProcessBridgeParent(
+      const ProcessId& aContentProcessId,
+      Endpoint<mozilla::net::PSocketProcessBridgeParent>&& aEndpoint);
+  mozilla::ipc::IPCResult RecvInitProfiler(
+      Endpoint<mozilla::PProfilerChild>&& aEndpoint);
+#if defined(MOZ_SANDBOX) && defined(MOZ_DEBUG) && defined(ENABLE_TESTS)
+  mozilla::ipc::IPCResult RecvInitSandboxTesting(
+      Endpoint<PSandboxTestingChild>&& aEndpoint);
+#endif
+  mozilla::ipc::IPCResult RecvSocketProcessTelemetryPing();
+
+  PWebrtcTCPSocketChild* AllocPWebrtcTCPSocketChild(const Maybe<TabId>& tabId);
+  bool DeallocPWebrtcTCPSocketChild(PWebrtcTCPSocketChild* aActor);
+
+  already_AddRefed<PHttpTransactionChild> AllocPHttpTransactionChild();
+
+  void CleanUp();
+  void DestroySocketProcessBridgeParent(ProcessId aId);
+
+  already_AddRefed<PHttpConnectionMgrChild> AllocPHttpConnectionMgrChild(
+      const HttpHandlerInitArgs& aArgs);
+  mozilla::ipc::IPCResult RecvUpdateDeviceModelId(const nsACString& aModelId);
+  mozilla::ipc::IPCResult RecvOnHttpActivityDistributorActivated(
+      const bool& aIsActivated);
+  mozilla::ipc::IPCResult RecvOnHttpActivityDistributorObserveProxyResponse(
+      const bool& aIsEnabled);
+  mozilla::ipc::IPCResult RecvOnHttpActivityDistributorObserveConnection(
+      const bool& aIsEnabled);
+
+  already_AddRefed<PInputChannelThrottleQueueChild>
+  AllocPInputChannelThrottleQueueChild(const uint32_t& aMeanBytesPerSecond,
+                                       const uint32_t& aMaxBytesPerSecond);
+
+  already_AddRefed<PAltSvcTransactionChild> AllocPAltSvcTransactionChild(
+      const HttpConnectionInfoCloneArgs& aConnInfo, const uint32_t& aCaps);
+
+  bool IsShuttingDown() { return mShuttingDown; }
+
+  already_AddRefed<PDNSRequestChild> AllocPDNSRequestChild(
+      const nsACString& aHost, const nsACString& aTrrServer,
+      const int32_t& aPort, const uint16_t& aType,
+      const OriginAttributes& aOriginAttributes,
+      const nsIDNSService::DNSFlags& aFlags);
+  mozilla::ipc::IPCResult RecvPDNSRequestConstructor(
+      PDNSRequestChild* aActor, const nsACString& aHost,
+      const nsACString& aTrrServer, const int32_t& aPort, const uint16_t& aType,
+      const OriginAttributes& aOriginAttributes,
+      const nsIDNSService::DNSFlags& aFlags) override;
+
+  void AddDataBridgeToMap(uint64_t aChannelId,
+                          BackgroundDataBridgeParent* aActor);
+  void RemoveDataBridgeFromMap(uint64_t aChannelId);
+  Maybe<RefPtr<BackgroundDataBridgeParent>> GetAndRemoveDataBridge(
+      uint64_t aChannelId);
+
+  mozilla::ipc::IPCResult RecvClearSessionCache(
+      ClearSessionCacheResolver&& aResolve);
+
+  already_AddRefed<PTRRServiceChild> AllocPTRRServiceChild(
+      const bool& aCaptiveIsPassed, const bool& aParentalControlEnabled,
+      const nsTArray<nsCString>& aDNSSuffixList);
+  mozilla::ipc::IPCResult RecvPTRRServiceConstructor(
+      PTRRServiceChild* aActor, const bool& aCaptiveIsPassed,
+      const bool& aParentalControlEnabled,
+      nsTArray<nsCString>&& aDNSSuffixList) override;
+
+  already_AddRefed<PNativeDNSResolverOverrideChild>
+  AllocPNativeDNSResolverOverrideChild();
+  mozilla::ipc::IPCResult RecvPNativeDNSResolverOverrideConstructor(
+      PNativeDNSResolverOverrideChild* aActor) override;
+
+  mozilla::ipc::IPCResult RecvNotifyObserver(const nsACString& aTopic,
+                                             const nsAString& aData);
+
+  mozilla::ipc::IPCResult RecvGetSocketData(GetSocketDataResolver&& aResolve);
+  mozilla::ipc::IPCResult RecvGetDNSCacheEntries(
+      GetDNSCacheEntriesResolver&& aResolve);
+  mozilla::ipc::IPCResult RecvGetHttpConnectionData(
+      GetHttpConnectionDataResolver&& aResolve);
+
+  mozilla::ipc::IPCResult RecvInitProxyAutoConfigChild(
+      Endpoint<PProxyAutoConfigChild>&& aEndpoint);
+
+  mozilla::ipc::IPCResult RecvRecheckIPConnectivity();
+  mozilla::ipc::IPCResult RecvRecheckDNS();
+
+  mozilla::ipc::IPCResult RecvFlushFOGData(FlushFOGDataResolver&& aResolver);
+
+  mozilla::ipc::IPCResult RecvTestTriggerMetrics(
+      TestTriggerMetricsResolver&& aResolve);
+
+#if defined(XP_WIN)
+  mozilla::ipc::IPCResult RecvGetUntrustedModulesData(
+      GetUntrustedModulesDataResolver&& aResolver);
+  mozilla::ipc::IPCResult RecvUnblockUntrustedModulesThread();
+#endif  // defined(XP_WIN)
+
+ protected:
+  friend class SocketProcessImpl;
+  ~SocketProcessChild();
+
+ private:
+  // Mapping of content process id and the SocketProcessBridgeParent.
+  // This table keeps SocketProcessBridgeParent alive in socket process.
+  nsRefPtrHashtable<nsUint32HashKey, SocketProcessBridgeParent>
+      mSocketProcessBridgeParentMap;
+
+  RefPtr<ChildProfilerController> mProfilerController;
+
+  bool mShuttingDown{false};
+  // Protect the table below.
+  Mutex mMutex MOZ_UNANNOTATED{"SocketProcessChild::mMutex"};
+  nsTHashMap<uint64_t, RefPtr<BackgroundDataBridgeParent>>
+      mBackgroundDataBridgeMap;
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_net_SocketProcessChild_h
diff --git a/netwerk/ipc/SocketProcessHost.cpp b/netwerk/ipc/SocketProcessHost.cpp
new file mode 100644
index 0000000000..931612d07c
--- /dev/null
+++ b/netwerk/ipc/SocketProcessHost.cpp
@@ -0,0 +1,319 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "SocketProcessHost.h"
+
+#include "SocketProcessParent.h"
+#include "mozilla/dom/ContentParent.h"
+#include "mozilla/ipc/FileDescriptor.h"
+#include "mozilla/ipc/ProcessUtils.h"
+#include "nsAppRunner.h"
+#include "nsIOService.h"
+#include "nsIObserverService.h"
+#include "ProfilerParent.h"
+#include "nsNetUtil.h"
+#include "mozilla/ipc/Endpoint.h"
+#include "mozilla/ipc/ProcessChild.h"
+
+#if defined(XP_LINUX) && defined(MOZ_SANDBOX)
+#  include "mozilla/SandboxBroker.h"
+#  include "mozilla/SandboxBrokerPolicyFactory.h"
+#  include "mozilla/SandboxSettings.h"
+#endif
+
+#if defined(XP_MACOSX) && defined(MOZ_SANDBOX)
+#  include "mozilla/Sandbox.h"
+#endif
+
+#if defined(XP_WIN)
+#  include "mozilla/WinDllServices.h"
+#endif
+
+using namespace mozilla::ipc;
+
+namespace mozilla {
+namespace net {
+
+#if defined(XP_MACOSX) && defined(MOZ_SANDBOX)
+bool SocketProcessHost::sLaunchWithMacSandbox = false;
+#endif
+
+SocketProcessHost::SocketProcessHost(Listener* aListener)
+    : GeckoChildProcessHost(GeckoProcessType_Socket),
+      mListener(aListener),
+      mTaskFactory(Some(this)),
+      mLaunchPhase(LaunchPhase::Unlaunched),
+      mShutdownRequested(false),
+      mChannelClosed(false) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_COUNT_CTOR(SocketProcessHost);
+#if defined(XP_MACOSX) && defined(MOZ_SANDBOX)
+  if (!sLaunchWithMacSandbox) {
+    sLaunchWithMacSandbox =
+        (PR_GetEnv("MOZ_DISABLE_SOCKET_PROCESS_SANDBOX") == nullptr);
+  }
+  mDisableOSActivityMode = sLaunchWithMacSandbox;
+#endif
+}
+
+SocketProcessHost::~SocketProcessHost() { MOZ_COUNT_DTOR(SocketProcessHost); }
+
+bool SocketProcessHost::Launch() {
+  MOZ_ASSERT(mLaunchPhase == LaunchPhase::Unlaunched);
+  MOZ_ASSERT(!mSocketProcessParent);
+  MOZ_ASSERT(NS_IsMainThread());
+
+  std::vector<std::string> extraArgs;
+  ProcessChild::AddPlatformBuildID(extraArgs);
+
+  SharedPreferenceSerializer prefSerializer;
+  if (!prefSerializer.SerializeToSharedMemory(GeckoProcessType_VR,
+                                              /* remoteType */ ""_ns)) {
+    return false;
+  }
+  prefSerializer.AddSharedPrefCmdLineArgs(*this, extraArgs);
+
+  mLaunchPhase = LaunchPhase::Waiting;
+  if (!GeckoChildProcessHost::LaunchAndWaitForProcessHandle(extraArgs)) {
+    mLaunchPhase = LaunchPhase::Complete;
+    return false;
+  }
+
+  return true;
+}
+
+static void HandleErrorAfterDestroy(
+    RefPtr<SocketProcessHost::Listener>&& aListener) {
+  if (!aListener) {
+    return;
+  }
+
+  NS_DispatchToMainThread(NS_NewRunnableFunction(
+      "HandleErrorAfterDestroy", [listener = std::move(aListener)]() {
+        listener->OnProcessLaunchComplete(nullptr, false);
+      }));
+}
+
+void SocketProcessHost::OnChannelConnected(base::ProcessId peer_pid) {
+  MOZ_ASSERT(!NS_IsMainThread());
+
+  GeckoChildProcessHost::OnChannelConnected(peer_pid);
+
+  // Post a task to the main thread. Take the lock because mTaskFactory is not
+  // thread-safe.
+  RefPtr<Runnable> runnable;
+  {
+    MonitorAutoLock lock(mMonitor);
+    if (!mTaskFactory) {
+      HandleErrorAfterDestroy(std::move(mListener));
+      return;
+    }
+    runnable =
+        (*mTaskFactory)
+            .NewRunnableMethod(&SocketProcessHost::OnChannelConnectedTask);
+  }
+  NS_DispatchToMainThread(runnable);
+}
+
+void SocketProcessHost::OnChannelError() {
+  MOZ_ASSERT(!NS_IsMainThread());
+  GeckoChildProcessHost::OnChannelError();
+
+  // Post a task to the main thread. Take the lock because mTaskFactory is not
+  // thread-safe.
+  RefPtr<Runnable> runnable;
+  {
+    MonitorAutoLock lock(mMonitor);
+    if (!mTaskFactory) {
+      HandleErrorAfterDestroy(std::move(mListener));
+      return;
+    }
+    runnable = (*mTaskFactory)
+                   .NewRunnableMethod(&SocketProcessHost::OnChannelErrorTask);
+  }
+  NS_DispatchToMainThread(runnable);
+}
+
+void SocketProcessHost::OnChannelConnectedTask() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (mLaunchPhase == LaunchPhase::Waiting) {
+    InitAfterConnect(true);
+  }
+}
+
+void SocketProcessHost::OnChannelErrorTask() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (mLaunchPhase == LaunchPhase::Waiting) {
+    InitAfterConnect(false);
+  }
+}
+
+void SocketProcessHost::InitAfterConnect(bool aSucceeded) {
+  MOZ_ASSERT(mLaunchPhase == LaunchPhase::Waiting);
+  MOZ_ASSERT(!mSocketProcessParent);
+  MOZ_ASSERT(NS_IsMainThread());
+
+  mLaunchPhase = LaunchPhase::Complete;
+  if (!aSucceeded) {
+    if (mListener) {
+      mListener->OnProcessLaunchComplete(this, false);
+    }
+    return;
+  }
+
+  mSocketProcessParent = MakeRefPtr<SocketProcessParent>(this);
+  DebugOnly<bool> rv = TakeInitialEndpoint().Bind(mSocketProcessParent.get());
+  MOZ_ASSERT(rv);
+
+  SocketPorcessInitAttributes attributes;
+  nsCOMPtr<nsIIOService> ioService(do_GetIOService());
+  MOZ_ASSERT(ioService, "No IO service?");
+  DebugOnly<nsresult> result = ioService->GetOffline(&attributes.mOffline());
+  MOZ_ASSERT(NS_SUCCEEDED(result), "Failed getting offline?");
+  result = ioService->GetConnectivity(&attributes.mConnectivity());
+  MOZ_ASSERT(NS_SUCCEEDED(result), "Failed getting connectivity?");
+
+  attributes.mInitSandbox() = false;
+
+#if defined(XP_WIN)
+  RefPtr<DllServices> dllSvc(DllServices::Get());
+  attributes.mIsReadyForBackgroundProcessing() =
+      dllSvc->IsReadyForBackgroundProcessing();
+#endif
+
+#if defined(XP_LINUX) && defined(MOZ_SANDBOX)
+  if (GetEffectiveSocketProcessSandboxLevel() > 0) {
+    auto policy = SandboxBrokerPolicyFactory::GetSocketProcessPolicy(
+        GetActor()->OtherPid());
+    if (policy != nullptr) {
+      attributes.mSandboxBroker() = Some(FileDescriptor());
+      mSandboxBroker =
+          SandboxBroker::Create(std::move(policy), GetActor()->OtherPid(),
+                                attributes.mSandboxBroker().ref());
+      // This is unlikely to fail and probably indicates OS resource
+      // exhaustion.
+      Unused << NS_WARN_IF(mSandboxBroker == nullptr);
+      MOZ_ASSERT(attributes.mSandboxBroker().ref().IsValid());
+    }
+    attributes.mInitSandbox() = true;
+  }
+#endif  // XP_LINUX && MOZ_SANDBOX
+
+  Unused << GetActor()->SendInit(attributes);
+
+  Unused << GetActor()->SendInitProfiler(
+      ProfilerParent::CreateForProcess(GetActor()->OtherPid()));
+
+  if (mListener) {
+    mListener->OnProcessLaunchComplete(this, true);
+  }
+}
+
+void SocketProcessHost::Shutdown() {
+  MOZ_ASSERT(!mShutdownRequested);
+  MOZ_ASSERT(NS_IsMainThread());
+
+  mListener = nullptr;
+
+  if (mSocketProcessParent) {
+    // OnChannelClosed uses this to check if the shutdown was expected or
+    // unexpected.
+    mShutdownRequested = true;
+
+    // The channel might already be closed if we got here unexpectedly.
+    if (!mChannelClosed) {
+      mSocketProcessParent->Close();
+    }
+
+    return;
+  }
+
+  DestroyProcess();
+}
+
+void SocketProcessHost::OnChannelClosed() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  mChannelClosed = true;
+
+  if (!mShutdownRequested && mListener) {
+    // This is an unclean shutdown. Notify our listener that we're going away.
+    mListener->OnProcessUnexpectedShutdown(this);
+  } else {
+    DestroyProcess();
+  }
+
+  // Release the actor.
+  SocketProcessParent::Destroy(std::move(mSocketProcessParent));
+  MOZ_ASSERT(!mSocketProcessParent);
+}
+
+void SocketProcessHost::DestroyProcess() {
+  {
+    MonitorAutoLock lock(mMonitor);
+    mTaskFactory.reset();
+  }
+
+  GetCurrentSerialEventTarget()->Dispatch(NS_NewRunnableFunction(
+      "DestroySocketProcessRunnable", [this] { Destroy(); }));
+}
+
+#if defined(XP_MACOSX) && defined(MOZ_SANDBOX)
+bool SocketProcessHost::FillMacSandboxInfo(MacSandboxInfo& aInfo) {
+  GeckoChildProcessHost::FillMacSandboxInfo(aInfo);
+  if (!aInfo.shouldLog && PR_GetEnv("MOZ_SANDBOX_SOCKET_PROCESS_LOGGING")) {
+    aInfo.shouldLog = true;
+  }
+  return true;
+}
+
+/* static */
+MacSandboxType SocketProcessHost::GetMacSandboxType() {
+  return MacSandboxType_Socket;
+}
+#endif
+
+//-----------------------------------------------------------------------------
+// SocketProcessMemoryReporter
+//-----------------------------------------------------------------------------
+
+bool SocketProcessMemoryReporter::IsAlive() const {
+  MOZ_ASSERT(gIOService);
+
+  if (!gIOService->mSocketProcess) {
+    return false;
+  }
+
+  return gIOService->mSocketProcess->IsConnected();
+}
+
+bool SocketProcessMemoryReporter::SendRequestMemoryReport(
+    const uint32_t& aGeneration, const bool& aAnonymize,
+    const bool& aMinimizeMemoryUsage,
+    const Maybe<ipc::FileDescriptor>& aDMDFile) {
+  MOZ_ASSERT(gIOService);
+
+  if (!gIOService->mSocketProcess) {
+    return false;
+  }
+
+  SocketProcessParent* actor = gIOService->mSocketProcess->GetActor();
+  if (!actor) {
+    return false;
+  }
+
+  return actor->SendRequestMemoryReport(aGeneration, aAnonymize,
+                                        aMinimizeMemoryUsage, aDMDFile);
+}
+
+int32_t SocketProcessMemoryReporter::Pid() const {
+  MOZ_ASSERT(gIOService);
+  return gIOService->SocketProcessPid();
+}
+
+}  // namespace net
+}  // namespace mozilla
diff --git a/netwerk/ipc/SocketProcessHost.h b/netwerk/ipc/SocketProcessHost.h
new file mode 100644
index 0000000000..df5ed9312a
--- /dev/null
+++ b/netwerk/ipc/SocketProcessHost.h
@@ -0,0 +1,152 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_SocketProcessHost_h
+#define mozilla_net_SocketProcessHost_h
+
+#include "mozilla/Maybe.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/ipc/GeckoChildProcessHost.h"
+#include "mozilla/MemoryReportingProcess.h"
+#include "mozilla/ipc/TaskFactory.h"
+
+namespace mozilla {
+
+#if defined(XP_LINUX) && defined(MOZ_SANDBOX)
+class SandboxBroker;
+#endif
+
+namespace net {
+
+class SocketProcessParent;
+
+// SocketProcessHost is the "parent process" container for a subprocess handle
+// and IPC connection. It owns the parent process IPDL actor, which in this
+// case, is a SocketProcessParent.
+// SocketProcessHost is allocated and managed by nsIOService in parent process.
+class SocketProcessHost final : public mozilla::ipc::GeckoChildProcessHost {
+  friend class SocketProcessParent;
+
+ public:
+  class Listener {
+   public:
+    NS_INLINE_DECL_THREADSAFE_REFCOUNTING(Listener)
+
+    // Called when the process of launching the process is complete.
+    virtual void OnProcessLaunchComplete(SocketProcessHost* aHost,
+                                         bool aSucceeded) = 0;
+
+    // Called when the channel is closed but Shutdown() is not invoked.
+    virtual void OnProcessUnexpectedShutdown(SocketProcessHost* aHost) = 0;
+
+   protected:
+    virtual ~Listener() = default;
+  };
+
+  explicit SocketProcessHost(Listener* listener);
+
+  // Launch the socket process asynchronously.
+  // The OnProcessLaunchComplete listener callback will be invoked
+  // either when a connection has been established, or if a connection
+  // could not be established due to an asynchronous error.
+  bool Launch();
+
+  // Inform the socket process that it should clean up its resources and shut
+  // down. This initiates an asynchronous shutdown sequence. After this method
+  // returns, it is safe for the caller to forget its pointer to the
+  // SocketProcessHost.
+  void Shutdown();
+
+  // Return the actor for the top-level actor of the process. Return null if
+  // the process is not connected.
+  SocketProcessParent* GetActor() const {
+    MOZ_ASSERT(NS_IsMainThread());
+
+    return mSocketProcessParent.get();
+  }
+
+  bool IsConnected() const {
+    MOZ_ASSERT(NS_IsMainThread());
+
+    return !!mSocketProcessParent;
+  }
+
+  // Called on the IO thread.
+  void OnChannelConnected(base::ProcessId peer_pid) override;
+  void OnChannelError() override;
+
+#if defined(XP_MACOSX) && defined(MOZ_SANDBOX)
+  // Return the sandbox type to be used with this process type.
+  static MacSandboxType GetMacSandboxType();
+#endif
+
+ private:
+  ~SocketProcessHost();
+
+  // Called on the main thread.
+  void OnChannelConnectedTask();
+  void OnChannelErrorTask();
+
+  // Called on the main thread after a connection has been established.
+  void InitAfterConnect(bool aSucceeded);
+
+  // Called on the main thread when the mSocketParent actor is shutting down.
+  void OnChannelClosed();
+
+  void DestroyProcess();
+
+#if defined(XP_MACOSX) && defined(MOZ_SANDBOX)
+  static bool sLaunchWithMacSandbox;
+
+  // Sandbox the Socket process at launch for all instances
+  bool IsMacSandboxLaunchEnabled() override { return sLaunchWithMacSandbox; }
+
+  // Override so we can turn on Socket process-specific sandbox logging
+  bool FillMacSandboxInfo(MacSandboxInfo& aInfo) override;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(SocketProcessHost);
+
+  RefPtr<Listener> mListener;
+  mozilla::Maybe<mozilla::ipc::TaskFactory<SocketProcessHost>> mTaskFactory;
+
+  enum class LaunchPhase { Unlaunched, Waiting, Complete };
+  LaunchPhase mLaunchPhase;
+
+  RefPtr<SocketProcessParent> mSocketProcessParent;
+  // mShutdownRequested is set to true only when Shutdown() is called.
+  // If mShutdownRequested is false and the IPC channel is closed,
+  // OnProcessUnexpectedShutdown will be invoked.
+  bool mShutdownRequested;
+  bool mChannelClosed;
+
+#if defined(XP_LINUX) && defined(MOZ_SANDBOX)
+  UniquePtr<SandboxBroker> mSandboxBroker;
+#endif
+};
+
+class SocketProcessMemoryReporter : public MemoryReportingProcess {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(SocketProcessMemoryReporter, override)
+
+  SocketProcessMemoryReporter() = default;
+
+  bool IsAlive() const override;
+
+  bool SendRequestMemoryReport(
+      const uint32_t& aGeneration, const bool& aAnonymize,
+      const bool& aMinimizeMemoryUsage,
+      const Maybe<mozilla::ipc::FileDescriptor>& aDMDFile) override;
+
+  int32_t Pid() const override;
+
+ protected:
+  virtual ~SocketProcessMemoryReporter() = default;
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_net_SocketProcessHost_h
diff --git a/netwerk/ipc/SocketProcessImpl.cpp b/netwerk/ipc/SocketProcessImpl.cpp
new file mode 100644
index 0000000000..40c64dc2bb
--- /dev/null
+++ b/netwerk/ipc/SocketProcessImpl.cpp
@@ -0,0 +1,76 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "SocketProcessImpl.h"
+
+#include "base/command_line.h"
+#include "base/shared_memory.h"
+#include "base/string_util.h"
+#include "mozilla/BackgroundHangMonitor.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/GeckoArgs.h"
+#include "mozilla/ipc/ProcessUtils.h"
+#include "mozilla/ipc/IOThreadChild.h"
+
+#if defined(OS_WIN) && defined(MOZ_SANDBOX)
+#  include "mozilla/sandboxTarget.h"
+#elif defined(__OpenBSD__) && defined(MOZ_SANDBOX)
+#  include "mozilla/SandboxSettings.h"
+#  include "prlink.h"
+#endif
+
+#ifdef OS_POSIX
+#  include <unistd.h>  // For sleep().
+#endif
+
+using mozilla::ipc::IOThreadChild;
+
+namespace mozilla {
+namespace net {
+
+LazyLogModule gSocketProcessLog("socketprocess");
+
+SocketProcessImpl::~SocketProcessImpl() = default;
+
+bool SocketProcessImpl::Init(int aArgc, char* aArgv[]) {
+#ifdef OS_POSIX
+  if (PR_GetEnv("MOZ_DEBUG_SOCKET_PROCESS")) {
+    printf_stderr("\n\nSOCKETPROCESSnSOCKETPROCESS\n  debug me @ %d\n\n",
+                  base::GetCurrentProcId());
+    sleep(30);
+  }
+#endif
+#if defined(MOZ_SANDBOX) && defined(OS_WIN)
+  LoadLibraryW(L"nss3.dll");
+  LoadLibraryW(L"softokn3.dll");
+  LoadLibraryW(L"freebl3.dll");
+  LoadLibraryW(L"ipcclientcerts.dll");
+  LoadLibraryW(L"winmm.dll");
+  mozilla::SandboxTarget::Instance()->StartSandbox();
+#elif defined(__OpenBSD__) && defined(MOZ_SANDBOX)
+  PR_LoadLibrary("libnss3.so");
+  PR_LoadLibrary("libsoftokn3.so");
+  PR_LoadLibrary("libfreebl3.so");
+  PR_LoadLibrary("libipcclientcerts.so");
+  StartOpenBSDSandbox(GeckoProcessType_Socket);
+#endif
+
+  Maybe<const char*> parentBuildID =
+      geckoargs::sParentBuildID.Get(aArgc, aArgv);
+  if (parentBuildID.isNothing()) {
+    return false;
+  }
+
+  if (!ProcessChild::InitPrefs(aArgc, aArgv)) {
+    return false;
+  }
+
+  return mSocketProcessChild->Init(TakeInitialEndpoint(), *parentBuildID);
+}
+
+void SocketProcessImpl::CleanUp() { mSocketProcessChild->CleanUp(); }
+
+}  // namespace net
+}  // namespace mozilla
diff --git a/netwerk/ipc/SocketProcessImpl.h b/netwerk/ipc/SocketProcessImpl.h
new file mode 100644
index 0000000000..c471ca2834
--- /dev/null
+++ b/netwerk/ipc/SocketProcessImpl.h
@@ -0,0 +1,35 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_SocketProcessImpl_h
+#define mozilla_net_SocketProcessImpl_h
+
+#include "mozilla/ipc/ProcessChild.h"
+#include "SocketProcessChild.h"
+
+namespace mozilla {
+namespace net {
+
+// This class owns the subprocess instance of socket child process.
+// It is instantiated as a singleton in XRE_InitChildProcess.
+class SocketProcessImpl final : public mozilla::ipc::ProcessChild {
+ protected:
+  using ProcessChild = mozilla::ipc::ProcessChild;
+
+ public:
+  using ProcessChild::ProcessChild;
+  ~SocketProcessImpl();
+
+  bool Init(int aArgc, char* aArgv[]) override;
+  void CleanUp() override;
+
+ private:
+  RefPtr<SocketProcessChild> mSocketProcessChild = new SocketProcessChild;
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_net_SocketProcessImpl_h
diff --git a/netwerk/ipc/SocketProcessLogging.h b/netwerk/ipc/SocketProcessLogging.h
new file mode 100644
index 0000000000..169de4986d
--- /dev/null
+++ b/netwerk/ipc/SocketProcessLogging.h
@@ -0,0 +1,20 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_SocketProcessLogging_h
+#define mozilla_SocketProcessLogging_h
+
+#include "mozilla/Logging.h"
+
+namespace mozilla {
+namespace net {
+extern LazyLogModule gSocketProcessLog;
+}
+}  // namespace mozilla
+
+#define LOG(msg) MOZ_LOG(gSocketProcessLog, mozilla::LogLevel::Debug, msg)
+#define LOG_ENABLED() MOZ_LOG_TEST(gSocketProcessLog, mozilla::LogLevel::Debug)
+
+#endif  // mozilla_SocketProcessLogging_h
diff --git a/netwerk/ipc/SocketProcessParent.cpp b/netwerk/ipc/SocketProcessParent.cpp
new file mode 100644
index 0000000000..dabd2a66ce
--- /dev/null
+++ b/netwerk/ipc/SocketProcessParent.cpp
@@ -0,0 +1,361 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "SocketProcessParent.h"
+#include "SocketProcessLogging.h"
+
+#include "AltServiceParent.h"
+#include "CachePushChecker.h"
+#include "HttpTransactionParent.h"
+#include "SocketProcessHost.h"
+#include "TLSClientAuthCertSelection.h"
+#include "mozilla/Components.h"
+#include "mozilla/dom/MemoryReportRequest.h"
+#include "mozilla/FOGIPC.h"
+#include "mozilla/net/DNSRequestParent.h"
+#include "mozilla/net/ProxyConfigLookupParent.h"
+#include "mozilla/RemoteLazyInputStreamParent.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/TelemetryIPC.h"
+#include "nsIAppStartup.h"
+#include "nsIConsoleService.h"
+#include "nsIHttpActivityObserver.h"
+#include "nsIObserverService.h"
+#include "nsNSSCertificate.h"
+#include "nsNSSComponent.h"
+#include "nsIOService.h"
+#include "nsHttpHandler.h"
+#include "nsHttpConnectionInfo.h"
+#include "secerr.h"
+#ifdef MOZ_WEBRTC
+#  include "mozilla/dom/ContentProcessManager.h"
+#  include "mozilla/dom/BrowserParent.h"
+#  include "mozilla/net/WebrtcTCPSocketParent.h"
+#endif
+#if defined(MOZ_WIDGET_ANDROID)
+#  include "mozilla/java/GeckoProcessManagerWrappers.h"
+#  include "mozilla/java/GeckoProcessTypeWrappers.h"
+#endif  // defined(MOZ_WIDGET_ANDROID)
+#if defined(XP_WIN)
+#  include "mozilla/WinDllServices.h"
+#endif
+
+namespace mozilla {
+namespace net {
+
+static SocketProcessParent* sSocketProcessParent;
+
+SocketProcessParent::SocketProcessParent(SocketProcessHost* aHost)
+    : mHost(aHost) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(mHost);
+
+  MOZ_COUNT_CTOR(SocketProcessParent);
+  sSocketProcessParent = this;
+}
+
+SocketProcessParent::~SocketProcessParent() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  MOZ_COUNT_DTOR(SocketProcessParent);
+  sSocketProcessParent = nullptr;
+}
+
+/* static */
+SocketProcessParent* SocketProcessParent::GetSingleton() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  return sSocketProcessParent;
+}
+
+void SocketProcessParent::ActorDestroy(ActorDestroyReason aWhy) {
+#if defined(MOZ_WIDGET_ANDROID)
+  nsCOMPtr<nsIEventTarget> launcherThread(ipc::GetIPCLauncher());
+  MOZ_ASSERT(launcherThread);
+
+  auto procType = java::GeckoProcessType::SOCKET();
+  auto selector =
+      java::GeckoProcessManager::Selector::New(procType, OtherPid());
+
+  launcherThread->Dispatch(NS_NewRunnableFunction(
+      "SocketProcessParent::ActorDestroy",
+      [selector = java::GeckoProcessManager::Selector::GlobalRef(selector)]() {
+        java::GeckoProcessManager::ShutdownProcess(selector);
+      }));
+#endif  // defined(MOZ_WIDGET_ANDROID)
+
+  if (aWhy == AbnormalShutdown) {
+    GenerateCrashReport(OtherPid());
+
+    if (PR_GetEnv("MOZ_CRASHREPORTER_SHUTDOWN")) {
+      printf_stderr("Shutting down due to socket process crash.\n");
+      nsCOMPtr<nsIAppStartup> appService =
+          do_GetService("@mozilla.org/toolkit/app-startup;1");
+      if (appService) {
+        bool userAllowedQuit = true;
+        appService->Quit(nsIAppStartup::eForceQuit, 1, &userAllowedQuit);
+      }
+    }
+  }
+
+  if (mHost) {
+    mHost->OnChannelClosed();
+  }
+}
+
+bool SocketProcessParent::SendRequestMemoryReport(
+    const uint32_t& aGeneration, const bool& aAnonymize,
+    const bool& aMinimizeMemoryUsage,
+    const Maybe<ipc::FileDescriptor>& aDMDFile) {
+  mMemoryReportRequest = MakeUnique<dom::MemoryReportRequestHost>(aGeneration);
+
+  PSocketProcessParent::SendRequestMemoryReport(
+      aGeneration, aAnonymize, aMinimizeMemoryUsage, aDMDFile,
+      [&](const uint32_t& aGeneration2) {
+        MOZ_ASSERT(gIOService);
+        if (!gIOService->SocketProcess()) {
+          return;
+        }
+        SocketProcessParent* actor = gIOService->SocketProcess()->GetActor();
+        if (!actor) {
+          return;
+        }
+        if (actor->mMemoryReportRequest) {
+          actor->mMemoryReportRequest->Finish(aGeneration2);
+          actor->mMemoryReportRequest = nullptr;
+        }
+      },
+      [&](mozilla::ipc::ResponseRejectReason) {
+        MOZ_ASSERT(gIOService);
+        if (!gIOService->SocketProcess()) {
+          return;
+        }
+        SocketProcessParent* actor = gIOService->SocketProcess()->GetActor();
+        if (!actor) {
+          return;
+        }
+        actor->mMemoryReportRequest = nullptr;
+      });
+
+  return true;
+}
+
+mozilla::ipc::IPCResult SocketProcessParent::RecvAddMemoryReport(
+    const MemoryReport& aReport) {
+  if (mMemoryReportRequest) {
+    mMemoryReportRequest->RecvReport(aReport);
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessParent::RecvAccumulateChildHistograms(
+    nsTArray<HistogramAccumulation>&& aAccumulations) {
+  TelemetryIPC::AccumulateChildHistograms(Telemetry::ProcessID::Socket,
+                                          aAccumulations);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessParent::RecvAccumulateChildKeyedHistograms(
+    nsTArray<KeyedHistogramAccumulation>&& aAccumulations) {
+  TelemetryIPC::AccumulateChildKeyedHistograms(Telemetry::ProcessID::Socket,
+                                               aAccumulations);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessParent::RecvUpdateChildScalars(
+    nsTArray<ScalarAction>&& aScalarActions) {
+  TelemetryIPC::UpdateChildScalars(Telemetry::ProcessID::Socket,
+                                   aScalarActions);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessParent::RecvUpdateChildKeyedScalars(
+    nsTArray<KeyedScalarAction>&& aScalarActions) {
+  TelemetryIPC::UpdateChildKeyedScalars(Telemetry::ProcessID::Socket,
+                                        aScalarActions);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessParent::RecvRecordChildEvents(
+    nsTArray<mozilla::Telemetry::ChildEventData>&& aEvents) {
+  TelemetryIPC::RecordChildEvents(Telemetry::ProcessID::Socket, aEvents);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessParent::RecvRecordDiscardedData(
+    const mozilla::Telemetry::DiscardedData& aDiscardedData) {
+  TelemetryIPC::RecordDiscardedData(Telemetry::ProcessID::Socket,
+                                    aDiscardedData);
+  return IPC_OK();
+}
+
+PWebrtcTCPSocketParent* SocketProcessParent::AllocPWebrtcTCPSocketParent(
+    const Maybe<TabId>& aTabId) {
+#ifdef MOZ_WEBRTC
+  WebrtcTCPSocketParent* parent = new WebrtcTCPSocketParent(aTabId);
+  parent->AddRef();
+  return parent;
+#else
+  return nullptr;
+#endif
+}
+
+bool SocketProcessParent::DeallocPWebrtcTCPSocketParent(
+    PWebrtcTCPSocketParent* aActor) {
+#ifdef MOZ_WEBRTC
+  WebrtcTCPSocketParent* parent = static_cast<WebrtcTCPSocketParent*>(aActor);
+  parent->Release();
+#endif
+  return true;
+}
+
+already_AddRefed<PDNSRequestParent> SocketProcessParent::AllocPDNSRequestParent(
+    const nsACString& aHost, const nsACString& aTrrServer, const int32_t& port,
+    const uint16_t& aType, const OriginAttributes& aOriginAttributes,
+    const nsIDNSService::DNSFlags& aFlags) {
+  RefPtr<DNSRequestHandler> handler = new DNSRequestHandler();
+  RefPtr<DNSRequestParent> actor = new DNSRequestParent(handler);
+  return actor.forget();
+}
+
+mozilla::ipc::IPCResult SocketProcessParent::RecvPDNSRequestConstructor(
+    PDNSRequestParent* aActor, const nsACString& aHost,
+    const nsACString& aTrrServer, const int32_t& port, const uint16_t& aType,
+    const OriginAttributes& aOriginAttributes,
+    const nsIDNSService::DNSFlags& aFlags) {
+  RefPtr<DNSRequestParent> actor = static_cast<DNSRequestParent*>(aActor);
+  RefPtr<DNSRequestHandler> handler =
+      actor->GetDNSRequest()->AsDNSRequestHandler();
+  handler->DoAsyncResolve(aHost, aTrrServer, port, aType, aOriginAttributes,
+                          aFlags);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessParent::RecvObserveHttpActivity(
+    const HttpActivityArgs& aArgs, const uint32_t& aActivityType,
+    const uint32_t& aActivitySubtype, const PRTime& aTimestamp,
+    const uint64_t& aExtraSizeData, const nsACString& aExtraStringData) {
+  nsCOMPtr<nsIHttpActivityDistributor> activityDistributor =
+      components::HttpActivityDistributor::Service();
+  MOZ_ASSERT(activityDistributor);
+
+  Unused << activityDistributor->ObserveActivityWithArgs(
+      aArgs, aActivityType, aActivitySubtype, aTimestamp, aExtraSizeData,
+      aExtraStringData);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessParent::RecvInitBackground(
+    Endpoint<PBackgroundStarterParent>&& aEndpoint) {
+  LOG(("SocketProcessParent::RecvInitBackground\n"));
+  if (!ipc::BackgroundParent::AllocStarter(nullptr, std::move(aEndpoint))) {
+    return IPC_FAIL(this, "BackgroundParent::Alloc failed");
+  }
+
+  return IPC_OK();
+}
+
+already_AddRefed<PAltServiceParent>
+SocketProcessParent::AllocPAltServiceParent() {
+  RefPtr<AltServiceParent> actor = new AltServiceParent();
+  return actor.forget();
+}
+
+already_AddRefed<PProxyConfigLookupParent>
+SocketProcessParent::AllocPProxyConfigLookupParent(
+    nsIURI* aURI, const uint32_t& aProxyResolveFlags) {
+  RefPtr<ProxyConfigLookupParent> actor =
+      new ProxyConfigLookupParent(aURI, aProxyResolveFlags);
+  return actor.forget();
+}
+
+mozilla::ipc::IPCResult SocketProcessParent::RecvPProxyConfigLookupConstructor(
+    PProxyConfigLookupParent* aActor, nsIURI* aURI,
+    const uint32_t& aProxyResolveFlags) {
+  static_cast<ProxyConfigLookupParent*>(aActor)->DoProxyLookup();
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessParent::RecvCachePushCheck(
+    nsIURI* aPushedURL, OriginAttributes&& aOriginAttributes,
+    nsCString&& aRequestString, CachePushCheckResolver&& aResolver) {
+  RefPtr<CachePushChecker> checker = new CachePushChecker(
+      aPushedURL, aOriginAttributes, aRequestString, aResolver);
+  if (NS_FAILED(checker->DoCheck())) {
+    aResolver(false);
+  }
+  return IPC_OK();
+}
+
+// To ensure that IPDL is finished before SocketParent gets deleted.
+class DeferredDeleteSocketProcessParent : public Runnable {
+ public:
+  explicit DeferredDeleteSocketProcessParent(
+      RefPtr<SocketProcessParent>&& aParent)
+      : Runnable("net::DeferredDeleteSocketProcessParent"),
+        mParent(std::move(aParent)) {}
+
+  NS_IMETHODIMP Run() override { return NS_OK; }
+
+ private:
+  RefPtr<SocketProcessParent> mParent;
+};
+
+/* static */
+void SocketProcessParent::Destroy(RefPtr<SocketProcessParent>&& aParent) {
+  NS_DispatchToMainThread(
+      new DeferredDeleteSocketProcessParent(std::move(aParent)));
+}
+
+mozilla::ipc::IPCResult SocketProcessParent::RecvExcludeHttp2OrHttp3(
+    const HttpConnectionInfoCloneArgs& aArgs) {
+  RefPtr<nsHttpConnectionInfo> cinfo =
+      nsHttpConnectionInfo::DeserializeHttpConnectionInfoCloneArgs(aArgs);
+  if (!cinfo) {
+    MOZ_ASSERT(false, "failed to deserizlize http connection info");
+    return IPC_OK();
+  }
+
+  if (cinfo->IsHttp3()) {
+    gHttpHandler->ExcludeHttp3(cinfo);
+  } else {
+    gHttpHandler->ExcludeHttp2(cinfo);
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessParent::RecvOnConsoleMessage(
+    const nsString& aMessage) {
+  nsCOMPtr<nsIConsoleService> consoleService =
+      do_GetService(NS_CONSOLESERVICE_CONTRACTID);
+  if (consoleService) {
+    consoleService->LogStringMessage(aMessage.get());
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult SocketProcessParent::RecvFOGData(ByteBuf&& aBuf) {
+  glean::FOGData(std::move(aBuf));
+  return IPC_OK();
+}
+
+#if defined(XP_WIN)
+mozilla::ipc::IPCResult SocketProcessParent::RecvGetModulesTrust(
+    ModulePaths&& aModPaths, bool aRunAtNormalPriority,
+    GetModulesTrustResolver&& aResolver) {
+  RefPtr<DllServices> dllSvc(DllServices::Get());
+  dllSvc->GetModulesTrust(std::move(aModPaths), aRunAtNormalPriority)
+      ->Then(
+          GetMainThreadSerialEventTarget(), __func__,
+          [aResolver](ModulesMapResult&& aResult) {
+            aResolver(Some(ModulesMapResult(std::move(aResult))));
+          },
+          [aResolver](nsresult aRv) { aResolver(Nothing()); });
+  return IPC_OK();
+}
+#endif  // defined(XP_WIN)
+
+}  // namespace net
+}  // namespace mozilla
diff --git a/netwerk/ipc/SocketProcessParent.h b/netwerk/ipc/SocketProcessParent.h
new file mode 100644
index 0000000000..fb78402886
--- /dev/null
+++ b/netwerk/ipc/SocketProcessParent.h
@@ -0,0 +1,125 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_SocketProcessParent_h
+#define mozilla_net_SocketProcessParent_h
+
+#include "mozilla/UniquePtr.h"
+#include "mozilla/ipc/BackgroundParent.h"
+#include "mozilla/ipc/CrashReporterHelper.h"
+#include "mozilla/ipc/InputStreamUtils.h"
+#include "mozilla/net/PSocketProcessParent.h"
+
+namespace mozilla {
+
+namespace dom {
+class MemoryReport;
+class MemoryReportRequestHost;
+}  // namespace dom
+
+namespace net {
+
+class SocketProcessHost;
+
+// IPC actor of socket process in parent process. This is allocated and managed
+// by SocketProcessHost.
+class SocketProcessParent final
+    : public PSocketProcessParent,
+      public ipc::CrashReporterHelper<GeckoProcessType_Socket> {
+ public:
+  friend class SocketProcessHost;
+
+  NS_INLINE_DECL_REFCOUNTING(SocketProcessParent, final)
+
+  explicit SocketProcessParent(SocketProcessHost* aHost);
+
+  static SocketProcessParent* GetSingleton();
+
+  mozilla::ipc::IPCResult RecvAddMemoryReport(const MemoryReport& aReport);
+  mozilla::ipc::IPCResult RecvAccumulateChildHistograms(
+      nsTArray<HistogramAccumulation>&& aAccumulations);
+  mozilla::ipc::IPCResult RecvAccumulateChildKeyedHistograms(
+      nsTArray<KeyedHistogramAccumulation>&& aAccumulations);
+  mozilla::ipc::IPCResult RecvUpdateChildScalars(
+      nsTArray<ScalarAction>&& aScalarActions);
+  mozilla::ipc::IPCResult RecvUpdateChildKeyedScalars(
+      nsTArray<KeyedScalarAction>&& aScalarActions);
+  mozilla::ipc::IPCResult RecvRecordChildEvents(
+      nsTArray<ChildEventData>&& events);
+  mozilla::ipc::IPCResult RecvRecordDiscardedData(
+      const DiscardedData& aDiscardedData);
+
+  PWebrtcTCPSocketParent* AllocPWebrtcTCPSocketParent(
+      const Maybe<TabId>& aTabId);
+  bool DeallocPWebrtcTCPSocketParent(PWebrtcTCPSocketParent* aActor);
+  already_AddRefed<PDNSRequestParent> AllocPDNSRequestParent(
+      const nsACString& aHost, const nsACString& aTrrServer,
+      const int32_t& port, const uint16_t& aType,
+      const OriginAttributes& aOriginAttributes,
+      const nsIDNSService::DNSFlags& aFlags);
+  virtual mozilla::ipc::IPCResult RecvPDNSRequestConstructor(
+      PDNSRequestParent* actor, const nsACString& aHost,
+      const nsACString& trrServer, const int32_t& port, const uint16_t& type,
+      const OriginAttributes& aOriginAttributes,
+      const nsIDNSService::DNSFlags& flags) override;
+
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+  bool SendRequestMemoryReport(const uint32_t& aGeneration,
+                               const bool& aAnonymize,
+                               const bool& aMinimizeMemoryUsage,
+                               const Maybe<ipc::FileDescriptor>& aDMDFile);
+
+  mozilla::ipc::IPCResult RecvObserveHttpActivity(
+      const HttpActivityArgs& aArgs, const uint32_t& aActivityType,
+      const uint32_t& aActivitySubtype, const PRTime& aTimestamp,
+      const uint64_t& aExtraSizeData, const nsACString& aExtraStringData);
+
+  mozilla::ipc::IPCResult RecvInitBackground(
+      Endpoint<PBackgroundStarterParent>&& aEndpoint);
+
+  already_AddRefed<PAltServiceParent> AllocPAltServiceParent();
+
+  mozilla::ipc::IPCResult RecvFindIPCClientCertObjects(
+      nsTArray<IPCClientCertObject>* aObjects);
+  mozilla::ipc::IPCResult RecvIPCClientCertSign(ByteArray aCert,
+                                                ByteArray aData,
+                                                ByteArray aParams,
+                                                ByteArray* aSignature);
+
+  already_AddRefed<PProxyConfigLookupParent> AllocPProxyConfigLookupParent(
+      nsIURI* aURI, const uint32_t& aProxyResolveFlags);
+  mozilla::ipc::IPCResult RecvPProxyConfigLookupConstructor(
+      PProxyConfigLookupParent* aActor, nsIURI* aURI,
+      const uint32_t& aProxyResolveFlags) override;
+
+  mozilla::ipc::IPCResult RecvCachePushCheck(
+      nsIURI* aPushedURL, OriginAttributes&& aOriginAttributes,
+      nsCString&& aRequestString, CachePushCheckResolver&& aResolver);
+
+  mozilla::ipc::IPCResult RecvExcludeHttp2OrHttp3(
+      const HttpConnectionInfoCloneArgs& aArgs);
+  mozilla::ipc::IPCResult RecvOnConsoleMessage(const nsString& aMessage);
+
+  mozilla::ipc::IPCResult RecvFOGData(ByteBuf&& aBuf);
+
+#if defined(XP_WIN)
+  mozilla::ipc::IPCResult RecvGetModulesTrust(
+      ModulePaths&& aModPaths, bool aRunAtNormalPriority,
+      GetModulesTrustResolver&& aResolver);
+#endif  // defined(XP_WIN)
+
+ private:
+  ~SocketProcessParent();
+
+  SocketProcessHost* mHost;
+  UniquePtr<dom::MemoryReportRequestHost> mMemoryReportRequest;
+
+  static void Destroy(RefPtr<SocketProcessParent>&& aParent);
+};
+
+}  // namespace net
+}  // namespace mozilla
+
+#endif  // mozilla_net_SocketProcessParent_h
diff --git a/netwerk/ipc/moz.build b/netwerk/ipc/moz.build
new file mode 100644
index 0000000000..16f164d638
--- /dev/null
+++ b/netwerk/ipc/moz.build
@@ -0,0 +1,112 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+EXPORTS.mozilla.net += [
+    "ChannelEventQueue.h",
+    "DocumentChannel.h",
+    "DocumentChannelChild.h",
+    "DocumentChannelParent.h",
+    "DocumentLoadListener.h",
+    "InputChannelThrottleQueueChild.h",
+    "InputChannelThrottleQueueParent.h",
+    "NeckoChild.h",
+    "NeckoCommon.h",
+    "NeckoMessageUtils.h",
+    "NeckoParent.h",
+    "NeckoTargetHolder.h",
+    "ParentChannelWrapper.h",
+    "ParentProcessDocumentChannel.h",
+    "ProxyAutoConfigChild.h",
+    "ProxyAutoConfigParent.h",
+    "ProxyConfigLookup.h",
+    "ProxyConfigLookupChild.h",
+    "ProxyConfigLookupParent.h",
+    "SocketProcessBridgeChild.h",
+    "SocketProcessBridgeParent.h",
+    "SocketProcessChild.h",
+    "SocketProcessHost.h",
+    "SocketProcessImpl.h",
+    "SocketProcessParent.h",
+]
+
+UNIFIED_SOURCES += [
+    "ChannelEventQueue.cpp",
+    "DocumentChannel.cpp",
+    "DocumentChannelChild.cpp",
+    "DocumentChannelParent.cpp",
+    "DocumentLoadListener.cpp",
+    "InputChannelThrottleQueueChild.cpp",
+    "InputChannelThrottleQueueParent.cpp",
+    "NeckoChild.cpp",
+    "NeckoCommon.cpp",
+    "NeckoParent.cpp",
+    "NeckoTargetHolder.cpp",
+    "ParentChannelWrapper.cpp",
+    "ParentProcessDocumentChannel.cpp",
+    "ProxyConfigLookup.cpp",
+    "ProxyConfigLookupChild.cpp",
+    "ProxyConfigLookupParent.cpp",
+    "SocketProcessBridgeChild.cpp",
+    "SocketProcessBridgeParent.cpp",
+    "SocketProcessChild.cpp",
+    "SocketProcessHost.cpp",
+    "SocketProcessImpl.cpp",
+    "SocketProcessParent.cpp",
+]
+
+SOURCES += [
+    "ProxyAutoConfigChild.cpp",
+    "ProxyAutoConfigParent.cpp",
+]
+
+
+PREPROCESSED_IPDL_SOURCES += [
+    "PNecko.ipdl",
+    "PSocketProcess.ipdl",
+]
+
+IPDL_SOURCES = [
+    "NeckoChannelParams.ipdlh",
+    "PDataChannel.ipdl",
+    "PDocumentChannel.ipdl",
+    "PFileChannel.ipdl",
+    "PInputChannelThrottleQueue.ipdl",
+    "PProxyAutoConfig.ipdl",
+    "PProxyConfigLookup.ipdl",
+    "PSimpleChannel.ipdl",
+    "PSocketProcessBridge.ipdl",
+]
+
+# needed so --disable-webrtc builds work (yes, a bit messy)
+if not CONFIG["MOZ_WEBRTC"]:
+    IPDL_SOURCES += [
+        "../../dom/media/webrtc/transport/ipc/PStunAddrsRequest.ipdl",
+        "../../dom/media/webrtc/transport/ipc/PWebrtcTCPSocket.ipdl",
+        "../../dom/media/webrtc/transport/ipc/WebrtcProxyConfig.ipdlh",
+    ]
+    EXPORTS.mozilla.net += [
+        "../../dom/media/webrtc/transport/ipc/NrIceStunAddrMessageUtils.h",
+        "../../dom/media/webrtc/transport/ipc/PStunAddrsParams.h",
+    ]
+
+include("/ipc/chromium/chromium-config.mozbuild")
+
+FINAL_LIBRARY = "xul"
+
+LOCAL_INCLUDES += [
+    "/caps",
+    "/dom/base",
+    "/dom/media/webrtc/transport",
+    "/media/webrtc",
+    "/modules/libjar",
+    "/netwerk/base",
+    "/netwerk/protocol/http",
+    "/security/manager/ssl",
+    "/xpcom/threads",
+]
+
+# Add libFuzzer configuration directives
+include("/tools/fuzzing/libfuzzer-config.mozbuild")