Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

14 files changed, 4424 insertions, 0 deletions

diff --git a/uriloader/base/moz.build b/uriloader/base/moz.build
new file mode 100644
index 0000000000..36282f6f14
--- /dev/null
+++ b/uriloader/base/moz.build
@@ -0,0 +1,43 @@
+# -*- 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/.
+
+include("/ipc/chromium/chromium-config.mozbuild")
+
+with Files("**"):
+    BUG_COMPONENT = ("Core", "Document Navigation")
+
+with Files("nsITransfer.idl"):
+    BUG_COMPONENT = ("Firefox", "File Handling")
+
+XPIDL_SOURCES += [
+    "nsCURILoader.idl",
+    "nsIContentHandler.idl",
+    "nsIDocumentLoader.idl",
+    "nsITransfer.idl",
+    "nsIURIContentListener.idl",
+    "nsIURILoader.idl",
+    "nsIWebProgress.idl",
+    "nsIWebProgressListener.idl",
+    "nsIWebProgressListener2.idl",
+]
+
+XPIDL_MODULE = "uriloader"
+
+EXPORTS += [
+    "nsDocLoader.h",
+    "nsURILoader.h",
+]
+
+UNIFIED_SOURCES += [
+    "nsDocLoader.cpp",
+    "nsURILoader.cpp",
+]
+
+LOCAL_INCLUDES += [
+    "/netwerk/base",
+]
+
+FINAL_LIBRARY = "xul"
diff --git a/uriloader/base/nsCURILoader.idl b/uriloader/base/nsCURILoader.idl
new file mode 100644
index 0000000000..82f17fc83e
--- /dev/null
+++ b/uriloader/base/nsCURILoader.idl
@@ -0,0 +1,18 @@
+/* -*- Mode: IDL; tab-width: 3; 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 "nsIURILoader.idl"
+
+/*
+nsCURILoader implements:
+-------------------------
+nsIURILoader
+*/
+
+%{ C++
+#define NS_CONTENT_HANDLER_CONTRACTID         "@mozilla.org/uriloader/content-handler;1"
+#define NS_CONTENT_HANDLER_CONTRACTID_PREFIX  NS_CONTENT_HANDLER_CONTRACTID "?type="
+%}
diff --git a/uriloader/base/nsDocLoader.cpp b/uriloader/base/nsDocLoader.cpp
new file mode 100644
index 0000000000..e1e46ccdce
--- /dev/null
+++ b/uriloader/base/nsDocLoader.cpp
@@ -0,0 +1,1612 @@
+/* -*- 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 "nspr.h"
+#include "mozilla/dom/BrowserChild.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/BasicEvents.h"
+#include "mozilla/Components.h"
+#include "mozilla/EventDispatcher.h"
+#include "mozilla/Logging.h"
+#include "mozilla/IntegerPrintfMacros.h"
+#include "mozilla/PresShell.h"
+
+#include "nsDocLoader.h"
+#include "nsDocShell.h"
+#include "nsLoadGroup.h"
+#include "nsNetUtil.h"
+#include "nsIHttpChannel.h"
+#include "nsIWebNavigation.h"
+#include "nsIWebProgressListener2.h"
+
+#include "nsString.h"
+
+#include "nsCOMPtr.h"
+#include "nscore.h"
+#include "nsIWeakReferenceUtils.h"
+#include "nsQueryObject.h"
+
+#include "nsPIDOMWindow.h"
+#include "nsGlobalWindow.h"
+
+#include "nsIStringBundle.h"
+
+#include "nsIDocShell.h"
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/DocGroup.h"
+#include "nsPresContext.h"
+#include "nsIAsyncVerifyRedirectCallback.h"
+#include "nsIBrowserDOMWindow.h"
+#include "nsGlobalWindow.h"
+#include "mozilla/ThrottledEventQueue.h"
+using namespace mozilla;
+using mozilla::DebugOnly;
+using mozilla::eLoad;
+using mozilla::EventDispatcher;
+using mozilla::LogLevel;
+using mozilla::WidgetEvent;
+using mozilla::dom::BrowserChild;
+using mozilla::dom::BrowsingContext;
+using mozilla::dom::Document;
+
+//
+// Log module for nsIDocumentLoader logging...
+//
+// To enable logging (see mozilla/Logging.h for full details):
+//
+//    set MOZ_LOG=DocLoader:5
+//    set MOZ_LOG_FILE=debug.log
+//
+// this enables LogLevel::Debug level information and places all output in
+// the file 'debug.log'.
+//
+mozilla::LazyLogModule gDocLoaderLog("DocLoader");
+
+#if defined(DEBUG)
+void GetURIStringFromRequest(nsIRequest* request, nsACString& name) {
+  if (request)
+    request->GetName(name);
+  else
+    name.AssignLiteral("???");
+}
+#endif /* DEBUG */
+
+void nsDocLoader::RequestInfoHashInitEntry(PLDHashEntryHdr* entry,
+                                           const void* key) {
+  // Initialize the entry with placement new
+  new (entry) nsRequestInfo(key);
+}
+
+void nsDocLoader::RequestInfoHashClearEntry(PLDHashTable* table,
+                                            PLDHashEntryHdr* entry) {
+  nsRequestInfo* info = static_cast<nsRequestInfo*>(entry);
+  info->~nsRequestInfo();
+}
+
+// this is used for mListenerInfoList.Contains()
+template <>
+class nsDefaultComparator<nsDocLoader::nsListenerInfo,
+                          nsIWebProgressListener*> {
+ public:
+  bool Equals(const nsDocLoader::nsListenerInfo& aInfo,
+              nsIWebProgressListener* const& aListener) const {
+    nsCOMPtr<nsIWebProgressListener> listener =
+        do_QueryReferent(aInfo.mWeakListener);
+    return aListener == listener;
+  }
+};
+
+/* static */ const PLDHashTableOps nsDocLoader::sRequestInfoHashOps = {
+    PLDHashTable::HashVoidPtrKeyStub, PLDHashTable::MatchEntryStub,
+    PLDHashTable::MoveEntryStub, nsDocLoader::RequestInfoHashClearEntry,
+    nsDocLoader::RequestInfoHashInitEntry};
+
+nsDocLoader::nsDocLoader(bool aNotifyAboutBackgroundRequests)
+    : mParent(nullptr),
+      mProgressStateFlags(0),
+      mCurrentSelfProgress(0),
+      mMaxSelfProgress(0),
+      mCurrentTotalProgress(0),
+      mMaxTotalProgress(0),
+      mRequestInfoHash(&sRequestInfoHashOps, sizeof(nsRequestInfo)),
+      mCompletedTotalProgress(0),
+      mIsLoadingDocument(false),
+      mIsRestoringDocument(false),
+      mDontFlushLayout(false),
+      mIsFlushingLayout(false),
+      mTreatAsBackgroundLoad(false),
+      mHasFakeOnLoadDispatched(false),
+      mIsReadyToHandlePostMessage(false),
+      mDocumentOpenedButNotLoaded(false),
+      mNotifyAboutBackgroundRequests(aNotifyAboutBackgroundRequests) {
+  ClearInternalProgress();
+
+  MOZ_LOG(gDocLoaderLog, LogLevel::Debug, ("DocLoader:%p: created.\n", this));
+}
+
+nsresult nsDocLoader::SetDocLoaderParent(nsDocLoader* aParent) {
+  mParent = aParent;
+  return NS_OK;
+}
+
+nsresult nsDocLoader::Init() {
+  RefPtr<net::nsLoadGroup> loadGroup = new net::nsLoadGroup();
+  nsresult rv = loadGroup->Init();
+  if (NS_FAILED(rv)) return rv;
+
+  loadGroup->SetGroupObserver(this, mNotifyAboutBackgroundRequests);
+
+  mLoadGroup = loadGroup;
+
+  MOZ_LOG(gDocLoaderLog, LogLevel::Debug,
+          ("DocLoader:%p: load group %p.\n", this, mLoadGroup.get()));
+
+  return NS_OK;
+}
+
+nsresult nsDocLoader::InitWithBrowsingContext(
+    BrowsingContext* aBrowsingContext) {
+  RefPtr<net::nsLoadGroup> loadGroup = new net::nsLoadGroup();
+  if (!aBrowsingContext->GetRequestContextId()) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+  nsresult rv = loadGroup->InitWithRequestContextId(
+      aBrowsingContext->GetRequestContextId());
+  if (NS_FAILED(rv)) return rv;
+
+  loadGroup->SetGroupObserver(this, mNotifyAboutBackgroundRequests);
+
+  mLoadGroup = loadGroup;
+
+  MOZ_LOG(gDocLoaderLog, LogLevel::Debug,
+          ("DocLoader:%p: load group %p.\n", this, mLoadGroup.get()));
+
+  return NS_OK;
+}
+
+nsDocLoader::~nsDocLoader() {
+  /*
+          |ClearWeakReferences()| here is intended to prevent people holding
+     weak references from re-entering this destructor since |QueryReferent()|
+     will |AddRef()| me, and the subsequent |Release()| will try to destroy me.
+     At this point there should be only weak references remaining (otherwise, we
+     wouldn't be getting destroyed).
+
+          An alternative would be incrementing our refcount (consider it a
+     compressed flag saying "Don't re-destroy.").  I haven't yet decided which
+     is better. [scc]
+  */
+  // XXXbz now that NS_IMPL_RELEASE stabilizes by setting refcount to 1, is
+  // this needed?
+  ClearWeakReferences();
+
+  Destroy();
+
+  MOZ_LOG(gDocLoaderLog, LogLevel::Debug, ("DocLoader:%p: deleted.\n", this));
+}
+
+/*
+ * Implementation of ISupports methods...
+ */
+NS_IMPL_CYCLE_COLLECTING_ADDREF(nsDocLoader)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(nsDocLoader)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsDocLoader)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIDocumentLoader)
+  NS_INTERFACE_MAP_ENTRY(nsIRequestObserver)
+  NS_INTERFACE_MAP_ENTRY(nsIDocumentLoader)
+  NS_INTERFACE_MAP_ENTRY(nsISupportsWeakReference)
+  NS_INTERFACE_MAP_ENTRY(nsIWebProgress)
+  NS_INTERFACE_MAP_ENTRY(nsIProgressEventSink)
+  NS_INTERFACE_MAP_ENTRY(nsIInterfaceRequestor)
+  NS_INTERFACE_MAP_ENTRY(nsIChannelEventSink)
+  NS_INTERFACE_MAP_ENTRY(nsISupportsPriority)
+  NS_INTERFACE_MAP_ENTRY_CONCRETE(nsDocLoader)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTION_WEAK(nsDocLoader, mChildrenInOnload)
+
+/*
+ * Implementation of nsIInterfaceRequestor methods...
+ */
+NS_IMETHODIMP nsDocLoader::GetInterface(const nsIID& aIID, void** aSink) {
+  nsresult rv = NS_ERROR_NO_INTERFACE;
+
+  NS_ENSURE_ARG_POINTER(aSink);
+
+  if (aIID.Equals(NS_GET_IID(nsILoadGroup))) {
+    *aSink = mLoadGroup;
+    NS_IF_ADDREF((nsISupports*)*aSink);
+    rv = NS_OK;
+  } else {
+    rv = QueryInterface(aIID, aSink);
+  }
+
+  return rv;
+}
+
+/* static */
+already_AddRefed<nsDocLoader> nsDocLoader::GetAsDocLoader(
+    nsISupports* aSupports) {
+  RefPtr<nsDocLoader> ret = do_QueryObject(aSupports);
+  return ret.forget();
+}
+
+/* static */
+nsresult nsDocLoader::AddDocLoaderAsChildOfRoot(nsDocLoader* aDocLoader) {
+  nsCOMPtr<nsIDocumentLoader> docLoaderService =
+      components::DocLoader::Service();
+  NS_ENSURE_TRUE(docLoaderService, NS_ERROR_UNEXPECTED);
+
+  RefPtr<nsDocLoader> rootDocLoader = GetAsDocLoader(docLoaderService);
+  NS_ENSURE_TRUE(rootDocLoader, NS_ERROR_UNEXPECTED);
+
+  return rootDocLoader->AddChildLoader(aDocLoader);
+}
+
+// TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1415230)
+MOZ_CAN_RUN_SCRIPT_BOUNDARY NS_IMETHODIMP nsDocLoader::Stop(void) {
+  nsresult rv = NS_OK;
+
+  MOZ_LOG(gDocLoaderLog, LogLevel::Debug,
+          ("DocLoader:%p: Stop() called\n", this));
+
+  NS_OBSERVER_ARRAY_NOTIFY_XPCOM_OBSERVERS(mChildList, Stop, ());
+
+  if (mLoadGroup) {
+    rv = mLoadGroup->CancelWithReason(NS_BINDING_ABORTED,
+                                      "nsDocLoader::Stop"_ns);
+  }
+
+  // Don't report that we're flushing layout so IsBusy returns false after a
+  // Stop call.
+  mIsFlushingLayout = false;
+
+  // Clear out mChildrenInOnload.  We're not going to fire our onload
+  // anyway at this point, and there's no issue with mChildrenInOnload
+  // after this, since mDocumentRequest will be null after the
+  // DocLoaderIsEmpty() call.
+  mChildrenInOnload.Clear();
+  nsCOMPtr<nsIDocShell> ds = do_QueryInterface(GetAsSupports(this));
+  Document* doc = ds ? ds->GetExtantDocument() : nullptr;
+  if (doc) {
+    doc->ClearOOPChildrenLoading();
+  }
+
+  // Make sure to call DocLoaderIsEmpty now so that we reset mDocumentRequest,
+  // etc, as needed.  We could be getting into here from a subframe onload, in
+  // which case the call to DocLoaderIsEmpty() is coming but hasn't quite
+  // happened yet, Canceling the loadgroup did nothing (because it was already
+  // empty), and we're about to start a new load (which is what triggered this
+  // Stop() call).
+
+  // XXXbz If the child frame loadgroups were requests in mLoadgroup, I suspect
+  // we wouldn't need the call here....
+
+  NS_ASSERTION(!IsBusy(), "Shouldn't be busy here");
+
+  // If Cancelling the load group only had pending subresource requests, then
+  // the group status will still be success, and we would fire the load event.
+  // We want to avoid that when we're aborting the load, so override the status
+  // with an explicit NS_BINDING_ABORTED value.
+  DocLoaderIsEmpty(false, Some(NS_BINDING_ABORTED));
+
+  return rv;
+}
+
+bool nsDocLoader::TreatAsBackgroundLoad() { return mTreatAsBackgroundLoad; }
+
+void nsDocLoader::SetBackgroundLoadIframe() { mTreatAsBackgroundLoad = true; }
+
+bool nsDocLoader::IsBusy() {
+  nsresult rv;
+
+  //
+  // A document loader is busy if either:
+  //
+  //   1. One of its children is in the middle of an onload handler.  Note that
+  //      the handler may have already removed this child from mChildList!
+  //   2. It is currently loading a document and either has parts of it still
+  //      loading, or has a busy child docloader.
+  //   3. It's currently flushing layout in DocLoaderIsEmpty().
+  //
+
+  nsCOMPtr<nsIDocShell> ds = do_QueryInterface(GetAsSupports(this));
+  Document* doc = ds ? ds->GetExtantDocument() : nullptr;
+  if (!mChildrenInOnload.IsEmpty() || (doc && doc->HasOOPChildrenLoading()) ||
+      mIsFlushingLayout) {
+    return true;
+  }
+
+  /* Is this document loader busy? */
+  if (!IsBlockingLoadEvent()) {
+    return false;
+  }
+
+  // Check if any in-process sub-document is awaiting its 'load' event:
+  bool busy;
+  rv = mLoadGroup->IsPending(&busy);
+  if (NS_FAILED(rv)) {
+    return false;
+  }
+  if (busy) {
+    return true;
+  }
+
+  /* check its child document loaders... */
+  uint32_t count = mChildList.Length();
+  for (uint32_t i = 0; i < count; i++) {
+    nsIDocumentLoader* loader = ChildAt(i);
+
+    // If 'dom.cross_origin_iframes_loaded_in_background' is set, the parent
+    // document treats cross domain iframes as background loading frame
+    if (loader && static_cast<nsDocLoader*>(loader)->TreatAsBackgroundLoad()) {
+      continue;
+    }
+    // This is a safe cast, because we only put nsDocLoader objects into the
+    // array
+    if (loader && static_cast<nsDocLoader*>(loader)->IsBusy()) return true;
+  }
+
+  return false;
+}
+
+NS_IMETHODIMP
+nsDocLoader::GetContainer(nsISupports** aResult) {
+  NS_ADDREF(*aResult = static_cast<nsIDocumentLoader*>(this));
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocLoader::GetLoadGroup(nsILoadGroup** aResult) {
+  nsresult rv = NS_OK;
+
+  if (nullptr == aResult) {
+    rv = NS_ERROR_NULL_POINTER;
+  } else {
+    *aResult = mLoadGroup;
+    NS_IF_ADDREF(*aResult);
+  }
+  return rv;
+}
+
+void nsDocLoader::Destroy() {
+  Stop();
+
+  // Remove the document loader from the parent list of loaders...
+  if (mParent) {
+    DebugOnly<nsresult> rv = mParent->RemoveChildLoader(this);
+    NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "RemoveChildLoader failed");
+  }
+
+  // Release all the information about network requests...
+  ClearRequestInfoHash();
+
+  mListenerInfoList.Clear();
+  mListenerInfoList.Compact();
+
+  mDocumentRequest = nullptr;
+
+  if (mLoadGroup) mLoadGroup->SetGroupObserver(nullptr);
+
+  DestroyChildren();
+}
+
+void nsDocLoader::DestroyChildren() {
+  uint32_t count = mChildList.Length();
+  // if the doc loader still has children...we need to enumerate the
+  // children and make them null out their back ptr to the parent doc
+  // loader
+  for (uint32_t i = 0; i < count; i++) {
+    nsIDocumentLoader* loader = ChildAt(i);
+
+    if (loader) {
+      // This is a safe cast, as we only put nsDocLoader objects into the
+      // array
+      DebugOnly<nsresult> rv =
+          static_cast<nsDocLoader*>(loader)->SetDocLoaderParent(nullptr);
+      NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "SetDocLoaderParent failed");
+    }
+  }
+  mChildList.Clear();
+}
+
+NS_IMETHODIMP
+nsDocLoader::OnStartRequest(nsIRequest* request) {
+  // called each time a request is added to the group.
+
+  // Some docloaders deal with background requests in their OnStartRequest
+  // override, but here we don't want to do anything with them, so return early.
+  nsLoadFlags loadFlags = 0;
+  request->GetLoadFlags(&loadFlags);
+  if (loadFlags & nsIRequest::LOAD_BACKGROUND) {
+    return NS_OK;
+  }
+
+  if (MOZ_LOG_TEST(gDocLoaderLog, LogLevel::Debug)) {
+    nsAutoCString name;
+    request->GetName(name);
+
+    uint32_t count = 0;
+    if (mLoadGroup) mLoadGroup->GetActiveCount(&count);
+
+    MOZ_LOG(gDocLoaderLog, LogLevel::Debug,
+            ("DocLoader:%p: OnStartRequest[%p](%s) mIsLoadingDocument=%s, %u "
+             "active URLs",
+             this, request, name.get(), (mIsLoadingDocument ? "true" : "false"),
+             count));
+  }
+
+  bool justStartedLoading = false;
+
+  if (!mIsLoadingDocument && (loadFlags & nsIChannel::LOAD_DOCUMENT_URI)) {
+    justStartedLoading = true;
+    mIsLoadingDocument = true;
+    mDocumentOpenedButNotLoaded = false;
+    ClearInternalProgress();  // only clear our progress if we are starting a
+                              // new load....
+  }
+
+  //
+  // Create a new nsRequestInfo for the request that is starting to
+  // load...
+  //
+  AddRequestInfo(request);
+
+  //
+  // Only fire a doStartDocumentLoad(...) if the document loader
+  // has initiated a load...  Otherwise, this notification has
+  // resulted from a request being added to the load group.
+  //
+  if (mIsLoadingDocument) {
+    if (loadFlags & nsIChannel::LOAD_DOCUMENT_URI) {
+      //
+      // Make sure that the document channel is null at this point...
+      // (unless its been redirected)
+      //
+      NS_ASSERTION(
+          (loadFlags & nsIChannel::LOAD_REPLACE) || !(mDocumentRequest.get()),
+          "Overwriting an existing document channel!");
+
+      // This request is associated with the entire document...
+      mDocumentRequest = request;
+      mLoadGroup->SetDefaultLoadRequest(request);
+
+      // Only fire the start document load notification for the first
+      // document URI...  Do not fire it again for redirections
+      //
+      if (justStartedLoading) {
+        // Update the progress status state
+        mProgressStateFlags = nsIWebProgressListener::STATE_START;
+
+        // Fire the start document load notification
+        doStartDocumentLoad();
+        return NS_OK;
+      }
+    }
+  }
+
+  NS_ASSERTION(!mIsLoadingDocument || mDocumentRequest,
+               "mDocumentRequest MUST be set for the duration of a page load!");
+
+  // This is the only way to catch document request start event after a redirect
+  // has occured without changing inherited Firefox behaviour significantly.
+  // Problem description:
+  // The combination of |STATE_START + STATE_IS_DOCUMENT| is only sent for
+  // initial request (see |doStartDocumentLoad| call above).
+  // And |STATE_REDIRECTING + STATE_IS_DOCUMENT| is sent with old channel, which
+  // makes it impossible to filter by destination URL (see
+  // |AsyncOnChannelRedirect| implementation).
+  // Fixing any of those bugs may cause unpredictable consequences in any part
+  // of the browser, so we just add a custom flag for this exact situation.
+  int32_t extraFlags = 0;
+  if (mIsLoadingDocument && !justStartedLoading &&
+      (loadFlags & nsIChannel::LOAD_DOCUMENT_URI) &&
+      (loadFlags & nsIChannel::LOAD_REPLACE)) {
+    extraFlags = nsIWebProgressListener::STATE_IS_REDIRECTED_DOCUMENT;
+  }
+  doStartURLLoad(request, extraFlags);
+
+  return NS_OK;
+}
+
+// TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1415230)
+MOZ_CAN_RUN_SCRIPT_BOUNDARY NS_IMETHODIMP
+nsDocLoader::OnStopRequest(nsIRequest* aRequest, nsresult aStatus) {
+  // Some docloaders deal with background requests in their OnStopRequest
+  // override, but here we don't want to do anything with them, so return early.
+  nsLoadFlags lf = 0;
+  aRequest->GetLoadFlags(&lf);
+  if (lf & nsIRequest::LOAD_BACKGROUND) {
+    return NS_OK;
+  }
+
+  nsresult rv = NS_OK;
+
+  if (MOZ_LOG_TEST(gDocLoaderLog, LogLevel::Debug)) {
+    nsAutoCString name;
+    aRequest->GetName(name);
+
+    uint32_t count = 0;
+    if (mLoadGroup) mLoadGroup->GetActiveCount(&count);
+
+    MOZ_LOG(gDocLoaderLog, LogLevel::Debug,
+            ("DocLoader:%p: OnStopRequest[%p](%s) status=%" PRIx32
+             " mIsLoadingDocument=%s, mDocumentOpenedButNotLoaded=%s,"
+             " %u active URLs",
+             this, aRequest, name.get(), static_cast<uint32_t>(aStatus),
+             (mIsLoadingDocument ? "true" : "false"),
+             (mDocumentOpenedButNotLoaded ? "true" : "false"), count));
+  }
+
+  bool fireTransferring = false;
+
+  //
+  // Set the Maximum progress to the same value as the current progress.
+  // Since the URI has finished loading, all the data is there.  Also,
+  // this will allow a more accurate estimation of the max progress (in case
+  // the old value was unknown ie. -1)
+  //
+  nsRequestInfo* info = GetRequestInfo(aRequest);
+  if (info) {
+    // Null out mLastStatus now so we don't find it when looking for
+    // status from now on.  This destroys the nsStatusInfo and hence
+    // removes it from our list.
+    info->mLastStatus = nullptr;
+
+    int64_t oldMax = info->mMaxProgress;
+
+    info->mMaxProgress = info->mCurrentProgress;
+
+    //
+    // If a request whose content-length was previously unknown has just
+    // finished loading, then use this new data to try to calculate a
+    // mMaxSelfProgress...
+    //
+    if ((oldMax < int64_t(0)) && (mMaxSelfProgress < int64_t(0))) {
+      mMaxSelfProgress = CalculateMaxProgress();
+    }
+
+    // As we know the total progress of this request now, save it to be part
+    // of CalculateMaxProgress() result. We need to remove the info from the
+    // hash, see bug 480713.
+    mCompletedTotalProgress += info->mMaxProgress;
+
+    //
+    // Determine whether a STATE_TRANSFERRING notification should be
+    // 'synthesized'.
+    //
+    // If nsRequestInfo::mMaxProgress (as stored in oldMax) and
+    // nsRequestInfo::mCurrentProgress are both 0, then the
+    // STATE_TRANSFERRING notification has not been fired yet...
+    //
+    if ((oldMax == 0) && (info->mCurrentProgress == 0)) {
+      nsCOMPtr<nsIChannel> channel(do_QueryInterface(aRequest));
+
+      // Only fire a TRANSFERRING notification if the request is also a
+      // channel -- data transfer requires a nsIChannel!
+      //
+      if (channel) {
+        if (NS_SUCCEEDED(aStatus)) {
+          fireTransferring = true;
+        }
+        //
+        // If the request failed (for any reason other than being
+        // redirected or retargeted), the TRANSFERRING notification can
+        // still be fired if a HTTP connection was established to a server.
+        //
+        else if (aStatus != NS_BINDING_REDIRECTED &&
+                 aStatus != NS_BINDING_RETARGETED) {
+          //
+          // Only if the load has been targeted (see bug 268483)...
+          //
+          if (lf & nsIChannel::LOAD_TARGETED) {
+            nsCOMPtr<nsIHttpChannel> httpChannel(do_QueryInterface(aRequest));
+            if (httpChannel) {
+              uint32_t responseCode;
+              rv = httpChannel->GetResponseStatus(&responseCode);
+              if (NS_SUCCEEDED(rv)) {
+                //
+                // A valid server status indicates that a connection was
+                // established to the server... So, fire the notification
+                // even though a failure occurred later...
+                //
+                fireTransferring = true;
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+
+  if (fireTransferring) {
+    // Send a STATE_TRANSFERRING notification for the request.
+    int32_t flags;
+
+    flags = nsIWebProgressListener::STATE_TRANSFERRING |
+            nsIWebProgressListener::STATE_IS_REQUEST;
+    //
+    // Move the WebProgress into the STATE_TRANSFERRING state if necessary...
+    //
+    if (mProgressStateFlags & nsIWebProgressListener::STATE_START) {
+      mProgressStateFlags = nsIWebProgressListener::STATE_TRANSFERRING;
+
+      // Send STATE_TRANSFERRING for the document too...
+      flags |= nsIWebProgressListener::STATE_IS_DOCUMENT;
+    }
+
+    FireOnStateChange(this, aRequest, flags, NS_OK);
+  }
+
+  //
+  // Fire the OnStateChange(...) notification for stop request
+  //
+  doStopURLLoad(aRequest, aStatus);
+
+  // Clear this request out of the hash to avoid bypass of FireOnStateChange
+  // when address of the request is reused.
+  RemoveRequestInfo(aRequest);
+
+  // For the special case where the current document is an initial about:blank
+  // document, we may still have subframes loading, and keeping the DocLoader
+  // busy. In that case, if we have an error, we won't show it until those
+  // frames finish loading, which is nonsensical. So stop any subframe loads
+  // now.
+  if (NS_FAILED(aStatus) && aStatus != NS_BINDING_ABORTED &&
+      aStatus != NS_BINDING_REDIRECTED && aStatus != NS_BINDING_RETARGETED) {
+    if (RefPtr<Document> doc = do_GetInterface(GetAsSupports(this))) {
+      if (doc->IsInitialDocument()) {
+        NS_OBSERVER_ARRAY_NOTIFY_XPCOM_OBSERVERS(mChildList, Stop, ());
+      }
+    }
+  }
+
+  //
+  // Only fire the DocLoaderIsEmpty(...) if we may need to fire onload.
+  //
+  if (IsBlockingLoadEvent()) {
+    nsCOMPtr<nsIDocShell> ds =
+        do_QueryInterface(static_cast<nsIRequestObserver*>(this));
+    bool doNotFlushLayout = false;
+    if (ds) {
+      // Don't do unexpected layout flushes while we're in process of restoring
+      // a document from the bfcache.
+      ds->GetRestoringDocument(&doNotFlushLayout);
+    }
+    DocLoaderIsEmpty(!doNotFlushLayout);
+  }
+
+  return NS_OK;
+}
+
+nsresult nsDocLoader::RemoveChildLoader(nsDocLoader* aChild) {
+  nsresult rv = mChildList.RemoveElement(aChild) ? NS_OK : NS_ERROR_FAILURE;
+  if (NS_SUCCEEDED(rv)) {
+    rv = aChild->SetDocLoaderParent(nullptr);
+  }
+  return rv;
+}
+
+nsresult nsDocLoader::AddChildLoader(nsDocLoader* aChild) {
+  mChildList.AppendElement(aChild);
+  return aChild->SetDocLoaderParent(this);
+}
+
+NS_IMETHODIMP nsDocLoader::GetDocumentChannel(nsIChannel** aChannel) {
+  if (!mDocumentRequest) {
+    *aChannel = nullptr;
+    return NS_OK;
+  }
+
+  return CallQueryInterface(mDocumentRequest, aChannel);
+}
+
+void nsDocLoader::DocLoaderIsEmpty(bool aFlushLayout,
+                                   const Maybe<nsresult>& aOverrideStatus) {
+  if (IsBlockingLoadEvent()) {
+    /* In the unimagineably rude circumstance that onload event handlers
+       triggered by this function actually kill the window ... ok, it's
+       not unimagineable; it's happened ... this deathgrip keeps this object
+       alive long enough to survive this function call. */
+    nsCOMPtr<nsIDocumentLoader> kungFuDeathGrip(this);
+
+    // Don't flush layout if we're still busy.
+    if (IsBusy()) {
+      return;
+    }
+
+    NS_ASSERTION(!mIsFlushingLayout, "Someone screwed up");
+    // We may not have a document request if we are in a
+    // document.open() situation.
+    NS_ASSERTION(mDocumentRequest || mDocumentOpenedButNotLoaded,
+                 "No Document Request!");
+
+    // The load group for this DocumentLoader is idle.  Flush if we need to.
+    if (aFlushLayout && !mDontFlushLayout) {
+      nsCOMPtr<Document> doc = do_GetInterface(GetAsSupports(this));
+      if (doc) {
+        // We start loads from style resolution, so we need to flush out style
+        // no matter what.  If we have user fonts, we also need to flush layout,
+        // since the reflow is what starts font loads.
+        mozilla::FlushType flushType = mozilla::FlushType::Style;
+        // Be safe in case this presshell is in teardown now
+        doc->FlushUserFontSet();
+        if (doc->GetUserFontSet()) {
+          flushType = mozilla::FlushType::Layout;
+        }
+        mDontFlushLayout = mIsFlushingLayout = true;
+        doc->FlushPendingNotifications(flushType);
+        mDontFlushLayout = mIsFlushingLayout = false;
+      }
+    }
+
+    // And now check whether we're really busy; that might have changed with
+    // the layout flush.
+    //
+    // Note, mDocumentRequest can be null while mDocumentOpenedButNotLoaded is
+    // false if the flushing above re-entered this method.
+    if (IsBusy() || (!mDocumentRequest && !mDocumentOpenedButNotLoaded)) {
+      return;
+    }
+
+    if (mDocumentRequest) {
+      // Clear out our request info hash, now that our load really is done and
+      // we don't need it anymore to CalculateMaxProgress().
+      ClearInternalProgress();
+
+      MOZ_LOG(gDocLoaderLog, LogLevel::Debug,
+              ("DocLoader:%p: Is now idle...\n", this));
+
+      nsCOMPtr<nsIRequest> docRequest = mDocumentRequest;
+
+      mDocumentRequest = nullptr;
+      mIsLoadingDocument = false;
+
+      // Update the progress status state - the document is done
+      mProgressStateFlags = nsIWebProgressListener::STATE_STOP;
+
+      nsresult loadGroupStatus = NS_OK;
+      if (aOverrideStatus) {
+        loadGroupStatus = *aOverrideStatus;
+      } else {
+        mLoadGroup->GetStatus(&loadGroupStatus);
+      }
+
+      //
+      // New code to break the circular reference between
+      // the load group and the docloader...
+      //
+      mLoadGroup->SetDefaultLoadRequest(nullptr);
+
+      // Take a ref to our parent now so that we can call ChildDoneWithOnload()
+      // on it even if our onload handler removes us from the docloader tree.
+      RefPtr<nsDocLoader> parent = mParent;
+
+      // Note that if calling ChildEnteringOnload() on the parent returns false
+      // then calling our onload handler is not safe.  That can only happen on
+      // OOM, so that's ok.
+      if (!parent || parent->ChildEnteringOnload(this)) {
+        // Do nothing with our state after firing the
+        // OnEndDocumentLoad(...). The document loader may be loading a *new*
+        // document - if LoadDocument() was called from a handler!
+        //
+        doStopDocumentLoad(docRequest, loadGroupStatus);
+
+        NotifyDoneWithOnload(parent);
+      }
+    } else {
+      MOZ_ASSERT(mDocumentOpenedButNotLoaded);
+      mDocumentOpenedButNotLoaded = false;
+
+      // Make sure we do the ChildEnteringOnload/ChildDoneWithOnload even if we
+      // plan to skip firing our own load event, because otherwise we might
+      // never end up firing our parent's load event.
+      RefPtr<nsDocLoader> parent = mParent;
+      if (!parent || parent->ChildEnteringOnload(this)) {
+        nsresult loadGroupStatus = NS_OK;
+        mLoadGroup->GetStatus(&loadGroupStatus);
+        // Make sure we're not canceling the loadgroup.  If we are, then just
+        // like the normal navigation case we should not fire a load event.
+        if (NS_SUCCEEDED(loadGroupStatus) ||
+            loadGroupStatus == NS_ERROR_PARSED_DATA_CACHED) {
+          // Can "doc" or "window" ever come back null here?  Our state machine
+          // is complicated enough I wouldn't bet against it...
+          nsCOMPtr<Document> doc = do_GetInterface(GetAsSupports(this));
+          if (doc) {
+            doc->SetReadyStateInternal(Document::READYSTATE_COMPLETE,
+                                       /* updateTimingInformation = */ false);
+            doc->StopDocumentLoad();
+
+            nsCOMPtr<nsPIDOMWindowOuter> window = doc->GetWindow();
+            if (window && !doc->SkipLoadEventAfterClose()) {
+              if (!mozilla::dom::DocGroup::TryToLoadIframesInBackground() ||
+                  (mozilla::dom::DocGroup::TryToLoadIframesInBackground() &&
+                   !HasFakeOnLoadDispatched())) {
+                MOZ_LOG(gDocLoaderLog, LogLevel::Debug,
+                        ("DocLoader:%p: Firing load event for document.open\n",
+                         this));
+
+                // This is a very cut-down version of
+                // nsDocumentViewer::LoadComplete that doesn't do various things
+                // that are not relevant here because this wasn't an actual
+                // navigation.
+                WidgetEvent event(true, eLoad);
+                event.mFlags.mBubbles = false;
+                event.mFlags.mCancelable = false;
+                // Dispatching to |window|, but using |document| as the target,
+                // per spec.
+                event.mTarget = doc;
+                nsEventStatus unused = nsEventStatus_eIgnore;
+                doc->SetLoadEventFiring(true);
+                EventDispatcher::Dispatch(window, nullptr, &event, nullptr,
+                                          &unused);
+                doc->SetLoadEventFiring(false);
+
+                // Now unsuppress painting on the presshell, if we
+                // haven't done that yet.
+                RefPtr<PresShell> presShell = doc->GetPresShell();
+                if (presShell && !presShell->IsDestroying()) {
+                  presShell->UnsuppressPainting();
+
+                  if (!presShell->IsDestroying()) {
+                    presShell->LoadComplete();
+                  }
+                }
+              }
+            }
+          }
+        }
+        NotifyDoneWithOnload(parent);
+      }
+    }
+  }
+}
+
+void nsDocLoader::NotifyDoneWithOnload(nsDocLoader* aParent) {
+  if (aParent) {
+    // In-process parent:
+    aParent->ChildDoneWithOnload(this);
+  }
+  nsCOMPtr<nsIDocShell> docShell = do_QueryInterface(this);
+  if (!docShell) {
+    return;
+  }
+  BrowsingContext* bc = nsDocShell::Cast(docShell)->GetBrowsingContext();
+  if (bc->IsContentSubframe() && !bc->GetParent()->IsInProcess()) {
+    if (BrowserChild* browserChild = BrowserChild::GetFrom(docShell)) {
+      mozilla::Unused << browserChild->SendMaybeFireEmbedderLoadEvents(
+          dom::EmbedderElementEventType::NoEvent);
+    }
+  }
+}
+
+void nsDocLoader::doStartDocumentLoad(void) {
+#if defined(DEBUG)
+  nsAutoCString buffer;
+
+  GetURIStringFromRequest(mDocumentRequest, buffer);
+  MOZ_LOG(
+      gDocLoaderLog, LogLevel::Debug,
+      ("DocLoader:%p: ++ Firing OnStateChange for start document load (...)."
+       "\tURI: %s \n",
+       this, buffer.get()));
+#endif /* DEBUG */
+
+  // Fire an OnStatus(...) notification STATE_START.  This indicates
+  // that the document represented by mDocumentRequest has started to
+  // load...
+  FireOnStateChange(this, mDocumentRequest,
+                    nsIWebProgressListener::STATE_START |
+                        nsIWebProgressListener::STATE_IS_DOCUMENT |
+                        nsIWebProgressListener::STATE_IS_REQUEST |
+                        nsIWebProgressListener::STATE_IS_WINDOW |
+                        nsIWebProgressListener::STATE_IS_NETWORK,
+                    NS_OK);
+}
+
+void nsDocLoader::doStartURLLoad(nsIRequest* request, int32_t aExtraFlags) {
+#if defined(DEBUG)
+  nsAutoCString buffer;
+
+  GetURIStringFromRequest(request, buffer);
+  MOZ_LOG(gDocLoaderLog, LogLevel::Debug,
+          ("DocLoader:%p: ++ Firing OnStateChange start url load (...)."
+           "\tURI: %s\n",
+           this, buffer.get()));
+#endif /* DEBUG */
+
+  FireOnStateChange(this, request,
+                    nsIWebProgressListener::STATE_START |
+                        nsIWebProgressListener::STATE_IS_REQUEST | aExtraFlags,
+                    NS_OK);
+}
+
+void nsDocLoader::doStopURLLoad(nsIRequest* request, nsresult aStatus) {
+#if defined(DEBUG)
+  nsAutoCString buffer;
+
+  GetURIStringFromRequest(request, buffer);
+  MOZ_LOG(gDocLoaderLog, LogLevel::Debug,
+          ("DocLoader:%p: ++ Firing OnStateChange for end url load (...)."
+           "\tURI: %s status=%" PRIx32 "\n",
+           this, buffer.get(), static_cast<uint32_t>(aStatus)));
+#endif /* DEBUG */
+
+  FireOnStateChange(this, request,
+                    nsIWebProgressListener::STATE_STOP |
+                        nsIWebProgressListener::STATE_IS_REQUEST,
+                    aStatus);
+
+  // Fire a status change message for the most recent unfinished
+  // request to make sure that the displayed status is not outdated.
+  if (!mStatusInfoList.isEmpty()) {
+    nsStatusInfo* statusInfo = mStatusInfoList.getFirst();
+    FireOnStatusChange(this, statusInfo->mRequest, statusInfo->mStatusCode,
+                       statusInfo->mStatusMessage.get());
+  }
+}
+
+void nsDocLoader::doStopDocumentLoad(nsIRequest* request, nsresult aStatus) {
+#if defined(DEBUG)
+  nsAutoCString buffer;
+
+  GetURIStringFromRequest(request, buffer);
+  MOZ_LOG(gDocLoaderLog, LogLevel::Debug,
+          ("DocLoader:%p: ++ Firing OnStateChange for end document load (...)."
+           "\tURI: %s Status=%" PRIx32 "\n",
+           this, buffer.get(), static_cast<uint32_t>(aStatus)));
+#endif /* DEBUG */
+
+  // Firing STATE_STOP|STATE_IS_DOCUMENT will fire onload handlers.
+  // Grab our parent chain before doing that so we can still dispatch
+  // STATE_STOP|STATE_IS_WINDW_STATE_IS_NETWORK to them all, even if
+  // the onload handlers rearrange the docshell tree.
+  WebProgressList list;
+  GatherAncestorWebProgresses(list);
+
+  //
+  // Fire an OnStateChange(...) notification indicating the the
+  // current document has finished loading...
+  //
+  int32_t flags = nsIWebProgressListener::STATE_STOP |
+                  nsIWebProgressListener::STATE_IS_DOCUMENT;
+  for (uint32_t i = 0; i < list.Length(); ++i) {
+    list[i]->DoFireOnStateChange(this, request, flags, aStatus);
+  }
+
+  //
+  // Fire a final OnStateChange(...) notification indicating the the
+  // current document has finished loading...
+  //
+  flags = nsIWebProgressListener::STATE_STOP |
+          nsIWebProgressListener::STATE_IS_WINDOW |
+          nsIWebProgressListener::STATE_IS_NETWORK;
+  for (uint32_t i = 0; i < list.Length(); ++i) {
+    list[i]->DoFireOnStateChange(this, request, flags, aStatus);
+  }
+}
+
+////////////////////////////////////////////////////////////////////////////////////
+// The following section contains support for nsIWebProgress and related stuff
+////////////////////////////////////////////////////////////////////////////////////
+
+NS_IMETHODIMP
+nsDocLoader::AddProgressListener(nsIWebProgressListener* aListener,
+                                 uint32_t aNotifyMask) {
+  if (mListenerInfoList.Contains(aListener)) {
+    // The listener is already registered!
+    return NS_ERROR_FAILURE;
+  }
+
+  nsWeakPtr listener = do_GetWeakReference(aListener);
+  if (!listener) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  mListenerInfoList.AppendElement(nsListenerInfo(listener, aNotifyMask));
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocLoader::RemoveProgressListener(nsIWebProgressListener* aListener) {
+  return mListenerInfoList.RemoveElement(aListener) ? NS_OK : NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsDocLoader::GetBrowsingContextXPCOM(BrowsingContext** aResult) {
+  *aResult = nullptr;
+  return NS_OK;
+}
+
+BrowsingContext* nsDocLoader::GetBrowsingContext() { return nullptr; }
+
+NS_IMETHODIMP
+nsDocLoader::GetDOMWindow(mozIDOMWindowProxy** aResult) {
+  return CallGetInterface(this, aResult);
+}
+
+NS_IMETHODIMP
+nsDocLoader::GetIsTopLevel(bool* aResult) {
+  nsCOMPtr<nsIDocShell> docShell = do_QueryInterface(this);
+  *aResult = docShell && docShell->GetBrowsingContext()->IsTop();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocLoader::GetIsLoadingDocument(bool* aIsLoadingDocument) {
+  *aIsLoadingDocument = mIsLoadingDocument;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocLoader::GetLoadType(uint32_t* aLoadType) {
+  *aLoadType = 0;
+
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsDocLoader::GetTarget(nsIEventTarget** aTarget) {
+  nsCOMPtr<mozIDOMWindowProxy> window;
+  nsresult rv = GetDOMWindow(getter_AddRefs(window));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(window);
+  NS_ENSURE_STATE(global);
+
+  nsCOMPtr<nsIEventTarget> target =
+      global->EventTargetFor(mozilla::TaskCategory::Other);
+  target.forget(aTarget);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocLoader::SetTarget(nsIEventTarget* aTarget) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+int64_t nsDocLoader::GetMaxTotalProgress() {
+  int64_t newMaxTotal = 0;
+
+  uint32_t count = mChildList.Length();
+  for (uint32_t i = 0; i < count; i++) {
+    int64_t individualProgress = 0;
+    nsIDocumentLoader* docloader = ChildAt(i);
+    if (docloader) {
+      // Cast is safe since all children are nsDocLoader too
+      individualProgress = ((nsDocLoader*)docloader)->GetMaxTotalProgress();
+    }
+    if (individualProgress < int64_t(0))  // if one of the elements doesn't know
+                                          // it's size then none of them do
+    {
+      newMaxTotal = int64_t(-1);
+      break;
+    } else
+      newMaxTotal += individualProgress;
+  }
+
+  int64_t progress = -1;
+  if (mMaxSelfProgress >= int64_t(0) && newMaxTotal >= int64_t(0))
+    progress = newMaxTotal + mMaxSelfProgress;
+
+  return progress;
+}
+
+////////////////////////////////////////////////////////////////////////////////////
+// The following section contains support for nsIProgressEventSink which is used
+// to pass progress and status between the actual request and the doc loader.
+// The doc loader then turns around and makes the right web progress calls based
+// on this information.
+////////////////////////////////////////////////////////////////////////////////////
+
+NS_IMETHODIMP nsDocLoader::OnProgress(nsIRequest* aRequest, int64_t aProgress,
+                                      int64_t aProgressMax) {
+  int64_t progressDelta = 0;
+
+  //
+  // Update the RequestInfo entry with the new progress data
+  //
+  if (nsRequestInfo* info = GetRequestInfo(aRequest)) {
+    // Update info->mCurrentProgress before we call FireOnStateChange,
+    // since that can make the "info" pointer invalid.
+    int64_t oldCurrentProgress = info->mCurrentProgress;
+    progressDelta = aProgress - oldCurrentProgress;
+    info->mCurrentProgress = aProgress;
+
+    // suppress sending STATE_TRANSFERRING if this is upload progress (see bug
+    // 240053)
+    if (!info->mUploading && (int64_t(0) == oldCurrentProgress) &&
+        (int64_t(0) == info->mMaxProgress)) {
+      //
+      // If we receive an OnProgress event from a toplevel channel that the URI
+      // Loader has not yet targeted, then we must suppress the event.  This is
+      // necessary to ensure that webprogresslisteners do not get confused when
+      // the channel is finally targeted.  See bug 257308.
+      //
+      nsLoadFlags lf = 0;
+      aRequest->GetLoadFlags(&lf);
+      if ((lf & nsIChannel::LOAD_DOCUMENT_URI) &&
+          !(lf & nsIChannel::LOAD_TARGETED)) {
+        MOZ_LOG(
+            gDocLoaderLog, LogLevel::Debug,
+            ("DocLoader:%p Ignoring OnProgress while load is not targeted\n",
+             this));
+        return NS_OK;
+      }
+
+      //
+      // This is the first progress notification for the entry.  If
+      // (aMaxProgress != -1) then the content-length of the data is known,
+      // so update mMaxSelfProgress...  Otherwise, set it to -1 to indicate
+      // that the content-length is no longer known.
+      //
+      if (aProgressMax != -1) {
+        mMaxSelfProgress += aProgressMax;
+        info->mMaxProgress = aProgressMax;
+      } else {
+        mMaxSelfProgress = int64_t(-1);
+        info->mMaxProgress = int64_t(-1);
+      }
+
+      // Send a STATE_TRANSFERRING notification for the request.
+      int32_t flags;
+
+      flags = nsIWebProgressListener::STATE_TRANSFERRING |
+              nsIWebProgressListener::STATE_IS_REQUEST;
+      //
+      // Move the WebProgress into the STATE_TRANSFERRING state if necessary...
+      //
+      if (mProgressStateFlags & nsIWebProgressListener::STATE_START) {
+        mProgressStateFlags = nsIWebProgressListener::STATE_TRANSFERRING;
+
+        // Send STATE_TRANSFERRING for the document too...
+        flags |= nsIWebProgressListener::STATE_IS_DOCUMENT;
+      }
+
+      FireOnStateChange(this, aRequest, flags, NS_OK);
+    }
+
+    // Update our overall current progress count.
+    mCurrentSelfProgress += progressDelta;
+  }
+  //
+  // The request is not part of the load group, so ignore its progress
+  // information...
+  //
+  else {
+#if defined(DEBUG)
+    nsAutoCString buffer;
+
+    GetURIStringFromRequest(aRequest, buffer);
+    MOZ_LOG(
+        gDocLoaderLog, LogLevel::Debug,
+        ("DocLoader:%p OOPS - No Request Info for: %s\n", this, buffer.get()));
+#endif /* DEBUG */
+
+    return NS_OK;
+  }
+
+  //
+  // Fire progress notifications out to any registered nsIWebProgressListeners
+  //
+  FireOnProgressChange(this, aRequest, aProgress, aProgressMax, progressDelta,
+                       mCurrentTotalProgress, mMaxTotalProgress);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsDocLoader::OnStatus(nsIRequest* aRequest, nsresult aStatus,
+                                    const char16_t* aStatusArg) {
+  //
+  // Fire progress notifications out to any registered nsIWebProgressListeners
+  //
+  if (aStatus != NS_OK) {
+    // Remember the current status for this request
+    nsRequestInfo* info;
+    info = GetRequestInfo(aRequest);
+    if (info) {
+      bool uploading = (aStatus == NS_NET_STATUS_WRITING ||
+                        aStatus == NS_NET_STATUS_SENDING_TO);
+      // If switching from uploading to downloading (or vice versa), then we
+      // need to reset our progress counts.  This is designed with HTTP form
+      // submission in mind, where an upload is performed followed by download
+      // of possibly several documents.
+      if (info->mUploading != uploading) {
+        mCurrentSelfProgress = mMaxSelfProgress = 0;
+        mCurrentTotalProgress = mMaxTotalProgress = 0;
+        mCompletedTotalProgress = 0;
+        info->mUploading = uploading;
+        info->mCurrentProgress = 0;
+        info->mMaxProgress = 0;
+      }
+    }
+
+    nsCOMPtr<nsIStringBundleService> sbs =
+        mozilla::components::StringBundle::Service();
+    if (!sbs) return NS_ERROR_FAILURE;
+    nsAutoString msg;
+    nsresult rv = sbs->FormatStatusMessage(aStatus, aStatusArg, msg);
+    if (NS_FAILED(rv)) return rv;
+
+    // Keep around the message. In case a request finishes, we need to make sure
+    // to send the status message of another request to our user to that we
+    // don't display, for example, "Transferring" messages for requests that are
+    // already done.
+    if (info) {
+      if (!info->mLastStatus) {
+        info->mLastStatus = MakeUnique<nsStatusInfo>(aRequest);
+      } else {
+        // We're going to move it to the front of the list, so remove
+        // it from wherever it is now.
+        info->mLastStatus->remove();
+      }
+      info->mLastStatus->mStatusMessage = msg;
+      info->mLastStatus->mStatusCode = aStatus;
+      // Put the info at the front of the list
+      mStatusInfoList.insertFront(info->mLastStatus.get());
+    }
+    FireOnStatusChange(this, aRequest, aStatus, msg.get());
+  }
+  return NS_OK;
+}
+
+void nsDocLoader::ClearInternalProgress() {
+  ClearRequestInfoHash();
+
+  mCurrentSelfProgress = mMaxSelfProgress = 0;
+  mCurrentTotalProgress = mMaxTotalProgress = 0;
+  mCompletedTotalProgress = 0;
+
+  mProgressStateFlags = nsIWebProgressListener::STATE_STOP;
+}
+
+/**
+ * |_code| is executed for every listener matching |_flag|
+ * |listener| should be used inside |_code| as the nsIWebProgressListener var.
+ */
+#define NOTIFY_LISTENERS(_flag, _code)                     \
+  PR_BEGIN_MACRO                                           \
+  nsCOMPtr<nsIWebProgressListener> listener;               \
+  ListenerArray::BackwardIterator iter(mListenerInfoList); \
+  while (iter.HasMore()) {                                 \
+    nsListenerInfo& info = iter.GetNext();                 \
+    if (!(info.mNotifyMask & (_flag))) {                   \
+      continue;                                            \
+    }                                                      \
+    listener = do_QueryReferent(info.mWeakListener);       \
+    if (!listener) {                                       \
+      iter.Remove();                                       \
+      continue;                                            \
+    }                                                      \
+    _code                                                  \
+  }                                                        \
+  mListenerInfoList.Compact();                             \
+  PR_END_MACRO
+
+void nsDocLoader::FireOnProgressChange(nsDocLoader* aLoadInitiator,
+                                       nsIRequest* request, int64_t aProgress,
+                                       int64_t aProgressMax,
+                                       int64_t aProgressDelta,
+                                       int64_t aTotalProgress,
+                                       int64_t aMaxTotalProgress) {
+  if (mIsLoadingDocument) {
+    mCurrentTotalProgress += aProgressDelta;
+    mMaxTotalProgress = GetMaxTotalProgress();
+
+    aTotalProgress = mCurrentTotalProgress;
+    aMaxTotalProgress = mMaxTotalProgress;
+  }
+
+#if defined(DEBUG)
+  nsAutoCString buffer;
+
+  GetURIStringFromRequest(request, buffer);
+  MOZ_LOG(gDocLoaderLog, LogLevel::Debug,
+          ("DocLoader:%p: Progress (%s): curSelf: %" PRId64 " maxSelf: %" PRId64
+           " curTotal: %" PRId64 " maxTotal %" PRId64 "\n",
+           this, buffer.get(), aProgress, aProgressMax, aTotalProgress,
+           aMaxTotalProgress));
+#endif /* DEBUG */
+
+  NOTIFY_LISTENERS(
+      nsIWebProgress::NOTIFY_PROGRESS,
+      // XXX truncates 64-bit to 32-bit
+      listener->OnProgressChange(aLoadInitiator, request, int32_t(aProgress),
+                                 int32_t(aProgressMax), int32_t(aTotalProgress),
+                                 int32_t(aMaxTotalProgress)););
+
+  // Pass the notification up to the parent...
+  if (mParent) {
+    mParent->FireOnProgressChange(aLoadInitiator, request, aProgress,
+                                  aProgressMax, aProgressDelta, aTotalProgress,
+                                  aMaxTotalProgress);
+  }
+}
+
+void nsDocLoader::GatherAncestorWebProgresses(WebProgressList& aList) {
+  for (nsDocLoader* loader = this; loader; loader = loader->mParent) {
+    aList.AppendElement(loader);
+  }
+}
+
+void nsDocLoader::FireOnStateChange(nsIWebProgress* aProgress,
+                                    nsIRequest* aRequest, int32_t aStateFlags,
+                                    nsresult aStatus) {
+  WebProgressList list;
+  GatherAncestorWebProgresses(list);
+  for (uint32_t i = 0; i < list.Length(); ++i) {
+    list[i]->DoFireOnStateChange(aProgress, aRequest, aStateFlags, aStatus);
+  }
+}
+
+void nsDocLoader::DoFireOnStateChange(nsIWebProgress* const aProgress,
+                                      nsIRequest* const aRequest,
+                                      int32_t& aStateFlags,
+                                      const nsresult aStatus) {
+  //
+  // Remove the STATE_IS_NETWORK bit if necessary.
+  //
+  // The rule is to remove this bit, if the notification has been passed
+  // up from a child WebProgress, and the current WebProgress is already
+  // active...
+  //
+  if (mIsLoadingDocument &&
+      (aStateFlags & nsIWebProgressListener::STATE_IS_NETWORK) &&
+      (this != aProgress)) {
+    aStateFlags &= ~nsIWebProgressListener::STATE_IS_NETWORK;
+  }
+
+  // Add the STATE_RESTORING bit if necessary.
+  if (mIsRestoringDocument)
+    aStateFlags |= nsIWebProgressListener::STATE_RESTORING;
+
+#if defined(DEBUG)
+  nsAutoCString buffer;
+
+  GetURIStringFromRequest(aRequest, buffer);
+  MOZ_LOG(gDocLoaderLog, LogLevel::Debug,
+          ("DocLoader:%p: Status (%s): code: %x\n", this, buffer.get(),
+           aStateFlags));
+#endif /* DEBUG */
+
+  NS_ASSERTION(aRequest,
+               "Firing OnStateChange(...) notification with a NULL request!");
+
+  NOTIFY_LISTENERS(
+      ((aStateFlags >> 16) & nsIWebProgress::NOTIFY_STATE_ALL),
+      listener->OnStateChange(aProgress, aRequest, aStateFlags, aStatus););
+}
+
+void nsDocLoader::FireOnLocationChange(nsIWebProgress* aWebProgress,
+                                       nsIRequest* aRequest, nsIURI* aUri,
+                                       uint32_t aFlags) {
+  NOTIFY_LISTENERS(
+      nsIWebProgress::NOTIFY_LOCATION,
+      MOZ_LOG(gDocLoaderLog, LogLevel::Debug,
+              ("DocLoader [%p] calling %p->OnLocationChange to %s %x", this,
+               listener.get(), aUri->GetSpecOrDefault().get(), aFlags));
+      listener->OnLocationChange(aWebProgress, aRequest, aUri, aFlags););
+
+  // Pass the notification up to the parent...
+  if (mParent) {
+    mParent->FireOnLocationChange(aWebProgress, aRequest, aUri, aFlags);
+  }
+}
+
+void nsDocLoader::FireOnStatusChange(nsIWebProgress* aWebProgress,
+                                     nsIRequest* aRequest, nsresult aStatus,
+                                     const char16_t* aMessage) {
+  NOTIFY_LISTENERS(
+      nsIWebProgress::NOTIFY_STATUS,
+      listener->OnStatusChange(aWebProgress, aRequest, aStatus, aMessage););
+
+  // Pass the notification up to the parent...
+  if (mParent) {
+    mParent->FireOnStatusChange(aWebProgress, aRequest, aStatus, aMessage);
+  }
+}
+
+bool nsDocLoader::RefreshAttempted(nsIWebProgress* aWebProgress, nsIURI* aURI,
+                                   uint32_t aDelay, bool aSameURI) {
+  /*
+   * Returns true if the refresh may proceed,
+   * false if the refresh should be blocked.
+   */
+  bool allowRefresh = true;
+
+  NOTIFY_LISTENERS(
+      nsIWebProgress::NOTIFY_REFRESH,
+      nsCOMPtr<nsIWebProgressListener2> listener2 =
+          do_QueryReferent(info.mWeakListener);
+      if (!listener2) continue;
+
+      bool listenerAllowedRefresh;
+      nsresult listenerRV = listener2->OnRefreshAttempted(
+          aWebProgress, aURI, aDelay, aSameURI, &listenerAllowedRefresh);
+      if (NS_FAILED(listenerRV)) continue;
+
+      allowRefresh = allowRefresh && listenerAllowedRefresh;);
+
+  // Pass the notification up to the parent...
+  if (mParent) {
+    allowRefresh = allowRefresh && mParent->RefreshAttempted(aWebProgress, aURI,
+                                                             aDelay, aSameURI);
+  }
+
+  return allowRefresh;
+}
+
+nsresult nsDocLoader::AddRequestInfo(nsIRequest* aRequest) {
+  if (!mRequestInfoHash.Add(aRequest, mozilla::fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  return NS_OK;
+}
+
+void nsDocLoader::RemoveRequestInfo(nsIRequest* aRequest) {
+  mRequestInfoHash.Remove(aRequest);
+}
+
+nsDocLoader::nsRequestInfo* nsDocLoader::GetRequestInfo(
+    nsIRequest* aRequest) const {
+  return static_cast<nsRequestInfo*>(mRequestInfoHash.Search(aRequest));
+}
+
+void nsDocLoader::ClearRequestInfoHash(void) { mRequestInfoHash.Clear(); }
+
+int64_t nsDocLoader::CalculateMaxProgress() {
+  int64_t max = mCompletedTotalProgress;
+  for (auto iter = mRequestInfoHash.Iter(); !iter.Done(); iter.Next()) {
+    auto info = static_cast<const nsRequestInfo*>(iter.Get());
+
+    if (info->mMaxProgress < info->mCurrentProgress) {
+      return int64_t(-1);
+    }
+    max += info->mMaxProgress;
+  }
+  return max;
+}
+
+NS_IMETHODIMP nsDocLoader::AsyncOnChannelRedirect(
+    nsIChannel* aOldChannel, nsIChannel* aNewChannel, uint32_t aFlags,
+    nsIAsyncVerifyRedirectCallback* cb) {
+  if (aOldChannel) {
+    nsLoadFlags loadFlags = 0;
+    int32_t stateFlags = nsIWebProgressListener::STATE_REDIRECTING |
+                         nsIWebProgressListener::STATE_IS_REQUEST;
+
+    aOldChannel->GetLoadFlags(&loadFlags);
+    // If the document channel is being redirected, then indicate that the
+    // document is being redirected in the notification...
+    if (loadFlags & nsIChannel::LOAD_DOCUMENT_URI) {
+      stateFlags |= nsIWebProgressListener::STATE_IS_DOCUMENT;
+
+#if defined(DEBUG)
+      // We only set mDocumentRequest in OnStartRequest(), but its possible
+      // to get a redirect before that for service worker interception.
+      if (mDocumentRequest) {
+        nsCOMPtr<nsIRequest> request(aOldChannel);
+        NS_ASSERTION(request == mDocumentRequest, "Wrong Document Channel");
+      }
+#endif /* DEBUG */
+    }
+
+    OnRedirectStateChange(aOldChannel, aNewChannel, aFlags, stateFlags);
+    FireOnStateChange(this, aOldChannel, stateFlags, NS_OK);
+  }
+
+  cb->OnRedirectVerifyCallback(NS_OK);
+  return NS_OK;
+}
+
+void nsDocLoader::OnSecurityChange(nsISupports* aContext, uint32_t aState) {
+  //
+  // Fire progress notifications out to any registered nsIWebProgressListeners.
+  //
+
+  nsCOMPtr<nsIRequest> request = do_QueryInterface(aContext);
+  nsIWebProgress* webProgress = static_cast<nsIWebProgress*>(this);
+
+  NOTIFY_LISTENERS(nsIWebProgress::NOTIFY_SECURITY,
+                   listener->OnSecurityChange(webProgress, request, aState););
+
+  // Pass the notification up to the parent...
+  if (mParent) {
+    mParent->OnSecurityChange(aContext, aState);
+  }
+}
+
+/*
+ * Implementation of nsISupportsPriority methods...
+ *
+ * The priority of the DocLoader _is_ the priority of its LoadGroup.
+ *
+ * XXX(darin): Once we start storing loadgroups in loadgroups, this code will
+ * go away.
+ */
+
+NS_IMETHODIMP nsDocLoader::GetPriority(int32_t* aPriority) {
+  nsCOMPtr<nsISupportsPriority> p = do_QueryInterface(mLoadGroup);
+  if (p) return p->GetPriority(aPriority);
+
+  *aPriority = 0;
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsDocLoader::SetPriority(int32_t aPriority) {
+  MOZ_LOG(gDocLoaderLog, LogLevel::Debug,
+          ("DocLoader:%p: SetPriority(%d) called\n", this, aPriority));
+
+  nsCOMPtr<nsISupportsPriority> p = do_QueryInterface(mLoadGroup);
+  if (p) p->SetPriority(aPriority);
+
+  NS_OBSERVER_ARRAY_NOTIFY_XPCOM_OBSERVERS(mChildList, SetPriority,
+                                           (aPriority));
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsDocLoader::AdjustPriority(int32_t aDelta) {
+  MOZ_LOG(gDocLoaderLog, LogLevel::Debug,
+          ("DocLoader:%p: AdjustPriority(%d) called\n", this, aDelta));
+
+  nsCOMPtr<nsISupportsPriority> p = do_QueryInterface(mLoadGroup);
+  if (p) p->AdjustPriority(aDelta);
+
+  NS_OBSERVER_ARRAY_NOTIFY_XPCOM_OBSERVERS(mChildList, AdjustPriority,
+                                           (aDelta));
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDocLoader::GetDocumentRequest(nsIRequest** aRequest) {
+  NS_IF_ADDREF(*aRequest = mDocumentRequest);
+  return NS_OK;
+}
+
+#if 0
+void nsDocLoader::DumpChannelInfo()
+{
+  nsChannelInfo *info;
+  int32_t i, count;
+  int32_t current=0, max=0;
+
+
+  printf("==== DocLoader=%x\n", this);
+
+  count = mChannelInfoList.Count();
+  for(i=0; i<count; i++) {
+    info = (nsChannelInfo *)mChannelInfoList.ElementAt(i);
+
+#  if defined(DEBUG)
+    nsAutoCString buffer;
+    nsresult rv = NS_OK;
+    if (info->mURI) {
+      rv = info->mURI->GetSpec(buffer);
+    }
+
+    printf("  [%d] current=%d  max=%d [%s]\n", i,
+           info->mCurrentProgress,
+           info->mMaxProgress, buffer.get());
+#  endif /* DEBUG */
+
+    current += info->mCurrentProgress;
+    if (max >= 0) {
+      if (info->mMaxProgress < info->mCurrentProgress) {
+        max = -1;
+      } else {
+        max += info->mMaxProgress;
+      }
+    }
+  }
+
+  printf("\nCurrent=%d   Total=%d\n====\n", current, max);
+}
+#endif   /* 0 */
diff --git a/uriloader/base/nsDocLoader.h b/uriloader/base/nsDocLoader.h
new file mode 100644
index 0000000000..e828cb8a11
--- /dev/null
+++ b/uriloader/base/nsDocLoader.h
@@ -0,0 +1,390 @@
+/* -*- 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 nsDocLoader_h__
+#define nsDocLoader_h__
+
+#include "nsIDocumentLoader.h"
+#include "nsIWebProgress.h"
+#include "nsIWebProgressListener.h"
+#include "nsIRequestObserver.h"
+#include "nsWeakReference.h"
+#include "nsILoadGroup.h"
+#include "nsCOMArray.h"
+#include "nsTObserverArray.h"
+#include "nsString.h"
+#include "nsIChannel.h"
+#include "nsIProgressEventSink.h"
+#include "nsIInterfaceRequestor.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsIChannelEventSink.h"
+#include "nsISupportsPriority.h"
+#include "nsCOMPtr.h"
+#include "PLDHashTable.h"
+#include "nsCycleCollectionParticipant.h"
+
+#include "mozilla/LinkedList.h"
+#include "mozilla/UniquePtr.h"
+
+namespace mozilla {
+namespace dom {
+class BrowsingContext;
+}  // namespace dom
+}  // namespace mozilla
+
+/****************************************************************************
+ * nsDocLoader implementation...
+ ****************************************************************************/
+
+#define NS_THIS_DOCLOADER_IMPL_CID                   \
+  { /* b4ec8387-98aa-4c08-93b6-6d23069c06f2 */       \
+    0xb4ec8387, 0x98aa, 0x4c08, {                    \
+      0x93, 0xb6, 0x6d, 0x23, 0x06, 0x9c, 0x06, 0xf2 \
+    }                                                \
+  }
+
+class nsDocLoader : public nsIDocumentLoader,
+                    public nsIRequestObserver,
+                    public nsSupportsWeakReference,
+                    public nsIProgressEventSink,
+                    public nsIWebProgress,
+                    public nsIInterfaceRequestor,
+                    public nsIChannelEventSink,
+                    public nsISupportsPriority {
+ public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_THIS_DOCLOADER_IMPL_CID)
+
+  nsDocLoader() : nsDocLoader(false) {}
+
+  [[nodiscard]] virtual nsresult Init();
+  [[nodiscard]] nsresult InitWithBrowsingContext(
+      mozilla::dom::BrowsingContext* aBrowsingContext);
+
+  static already_AddRefed<nsDocLoader> GetAsDocLoader(nsISupports* aSupports);
+  // Needed to deal with ambiguous inheritance from nsISupports...
+  static nsISupports* GetAsSupports(nsDocLoader* aDocLoader) {
+    return static_cast<nsIDocumentLoader*>(aDocLoader);
+  }
+
+  // Add aDocLoader as a child to the docloader service.
+  [[nodiscard]] static nsresult AddDocLoaderAsChildOfRoot(
+      nsDocLoader* aDocLoader);
+
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(nsDocLoader, nsIDocumentLoader)
+
+  NS_DECL_NSIDOCUMENTLOADER
+
+  // nsIProgressEventSink
+  NS_DECL_NSIPROGRESSEVENTSINK
+
+  // nsIRequestObserver methods: (for observing the load group)
+  NS_DECL_NSIREQUESTOBSERVER
+  NS_DECL_NSIWEBPROGRESS
+
+  NS_DECL_NSIINTERFACEREQUESTOR
+  NS_DECL_NSICHANNELEVENTSINK
+  NS_DECL_NSISUPPORTSPRIORITY;  // semicolon for clang-format bug 1629756
+
+  // Implementation specific methods...
+
+  // Remove aChild from our childlist.  This nulls out the child's mParent
+  // pointer.
+  [[nodiscard]] nsresult RemoveChildLoader(nsDocLoader* aChild);
+
+  // Add aChild to our child list.  This will set aChild's mParent pointer to
+  // |this|.
+  [[nodiscard]] nsresult AddChildLoader(nsDocLoader* aChild);
+  nsDocLoader* GetParent() const { return mParent; }
+
+  struct nsListenerInfo {
+    nsListenerInfo(nsIWeakReference* aListener, unsigned long aNotifyMask)
+        : mWeakListener(aListener), mNotifyMask(aNotifyMask) {}
+
+    // Weak pointer for the nsIWebProgressListener...
+    nsWeakPtr mWeakListener;
+
+    // Mask indicating which notifications the listener wants to receive.
+    unsigned long mNotifyMask;
+  };
+
+  /**
+   * Fired when a security change occurs due to page transitions,
+   * or end document load. This interface should be called by
+   * a security package (eg Netscape Personal Security Manager)
+   * to notify nsIWebProgressListeners that security state has
+   * changed. State flags are in nsIWebProgressListener.idl
+   */
+  void OnSecurityChange(nsISupports* aContext, uint32_t aState);
+
+  void SetDocumentOpenedButNotLoaded() { mDocumentOpenedButNotLoaded = true; }
+
+  bool TreatAsBackgroundLoad();
+
+  void SetFakeOnLoadDispatched() { mHasFakeOnLoadDispatched = true; };
+
+  bool HasFakeOnLoadDispatched() { return mHasFakeOnLoadDispatched; };
+
+  void ResetToFirstLoad() {
+    mHasFakeOnLoadDispatched = false;
+    mIsReadyToHandlePostMessage = false;
+    mTreatAsBackgroundLoad = false;
+  };
+
+  uint32_t ChildCount() const { return mChildList.Length(); }
+
+  // TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1415230)
+  MOZ_CAN_RUN_SCRIPT_BOUNDARY void OOPChildrenLoadingIsEmpty() {
+    DocLoaderIsEmpty(true);
+  }
+
+ protected:
+  explicit nsDocLoader(bool aNotifyAboutBackgroundRequests);
+  virtual ~nsDocLoader();
+
+  [[nodiscard]] virtual nsresult SetDocLoaderParent(nsDocLoader* aLoader);
+
+  bool IsBusy();
+
+  void SetBackgroundLoadIframe();
+
+  void Destroy();
+  virtual void DestroyChildren();
+
+  nsIDocumentLoader* ChildAt(int32_t i) {
+    return mChildList.SafeElementAt(i, nullptr);
+  }
+
+  void FireOnProgressChange(nsDocLoader* aLoadInitiator, nsIRequest* request,
+                            int64_t aProgress, int64_t aProgressMax,
+                            int64_t aProgressDelta, int64_t aTotalProgress,
+                            int64_t aMaxTotalProgress);
+
+  // This should be at least 2 long since we'll generally always
+  // have the current page and the global docloader on the ancestor
+  // list.  But to deal with frames it's better to make it a bit
+  // longer, and it's always a stack temporary so there's no real
+  // reason not to.
+  typedef AutoTArray<RefPtr<nsDocLoader>, 8> WebProgressList;
+  void GatherAncestorWebProgresses(WebProgressList& aList);
+
+  void FireOnStateChange(nsIWebProgress* aProgress, nsIRequest* request,
+                         int32_t aStateFlags, nsresult aStatus);
+
+  // The guts of FireOnStateChange, but does not call itself on our ancestors.
+  // The arguments that are const are const so that we can detect cases when
+  // DoFireOnStateChange wants to propagate changes to the next web progress
+  // at compile time.  The ones that are not, are references so that such
+  // changes can be propagated.
+  void DoFireOnStateChange(nsIWebProgress* const aProgress,
+                           nsIRequest* const request, int32_t& aStateFlags,
+                           const nsresult aStatus);
+
+  void FireOnStatusChange(nsIWebProgress* aWebProgress, nsIRequest* aRequest,
+                          nsresult aStatus, const char16_t* aMessage);
+
+  void FireOnLocationChange(nsIWebProgress* aWebProgress, nsIRequest* aRequest,
+                            nsIURI* aUri, uint32_t aFlags);
+
+  [[nodiscard]] bool RefreshAttempted(nsIWebProgress* aWebProgress,
+                                      nsIURI* aURI, uint32_t aDelay,
+                                      bool aSameURI);
+
+  // this function is overridden by the docshell, it is provided so that we
+  // can pass more information about redirect state (the normal OnStateChange
+  // doesn't get the new channel).
+  // @param aRedirectFlags The flags being sent to OnStateChange that
+  //                       indicate the type of redirect.
+  // @param aStateFlags    The channel flags normally sent to OnStateChange.
+  virtual void OnRedirectStateChange(nsIChannel* aOldChannel,
+                                     nsIChannel* aNewChannel,
+                                     uint32_t aRedirectFlags,
+                                     uint32_t aStateFlags) {}
+
+  void doStartDocumentLoad();
+  void doStartURLLoad(nsIRequest* request, int32_t aExtraFlags);
+  void doStopURLLoad(nsIRequest* request, nsresult aStatus);
+  void doStopDocumentLoad(nsIRequest* request, nsresult aStatus);
+
+  void NotifyDoneWithOnload(nsDocLoader* aParent);
+
+  // Inform a parent docloader that aChild is about to call its onload
+  // handler.
+  [[nodiscard]] bool ChildEnteringOnload(nsIDocumentLoader* aChild) {
+    // It's ok if we're already in the list -- we'll just be in there twice
+    // and then the RemoveObject calls from ChildDoneWithOnload will remove
+    // us.
+    return mChildrenInOnload.AppendObject(aChild);
+  }
+
+  // Inform a parent docloader that aChild is done calling its onload
+  // handler.
+  // TODO: Convert this to MOZ_CAN_RUN_SCRIPT (bug 1415230)
+  MOZ_CAN_RUN_SCRIPT_BOUNDARY void ChildDoneWithOnload(
+      nsIDocumentLoader* aChild) {
+    mChildrenInOnload.RemoveObject(aChild);
+    DocLoaderIsEmpty(true);
+  }
+
+  // DocLoaderIsEmpty should be called whenever the docloader may be empty.
+  // This method is idempotent and does nothing if the docloader is not in
+  // fact empty.  This method _does_ make sure that layout is flushed if our
+  // loadgroup has no active requests before checking for "real" emptiness if
+  // aFlushLayout is true.
+  // @param aOverrideStatus An optional status to use when notifying listeners
+  // of the completed load, instead of using the load group's status.
+  MOZ_CAN_RUN_SCRIPT void DocLoaderIsEmpty(
+      bool aFlushLayout,
+      const mozilla::Maybe<nsresult>& aOverrideStatus = mozilla::Nothing());
+
+ protected:
+  struct nsStatusInfo : public mozilla::LinkedListElement<nsStatusInfo> {
+    nsString mStatusMessage;
+    nsresult mStatusCode;
+    // Weak mRequest is ok; we'll be told if it decides to go away.
+    nsIRequest* const mRequest;
+
+    explicit nsStatusInfo(nsIRequest* aRequest)
+        : mStatusCode(NS_ERROR_NOT_INITIALIZED), mRequest(aRequest) {
+      MOZ_COUNT_CTOR(nsStatusInfo);
+    }
+    MOZ_COUNTED_DTOR(nsStatusInfo)
+  };
+
+  struct nsRequestInfo : public PLDHashEntryHdr {
+    explicit nsRequestInfo(const void* key)
+        : mKey(key),
+          mCurrentProgress(0),
+          mMaxProgress(0),
+          mUploading(false),
+          mLastStatus(nullptr) {
+      MOZ_COUNT_CTOR(nsRequestInfo);
+    }
+
+    MOZ_COUNTED_DTOR(nsRequestInfo)
+
+    nsIRequest* Request() {
+      return static_cast<nsIRequest*>(const_cast<void*>(mKey));
+    }
+
+    const void* mKey;  // Must be first for the PLDHashTable stubs to work
+    int64_t mCurrentProgress;
+    int64_t mMaxProgress;
+    bool mUploading;
+
+    mozilla::UniquePtr<nsStatusInfo> mLastStatus;
+  };
+
+  static void RequestInfoHashInitEntry(PLDHashEntryHdr* entry, const void* key);
+  static void RequestInfoHashClearEntry(PLDHashTable* table,
+                                        PLDHashEntryHdr* entry);
+
+  // IMPORTANT: The ownership implicit in the following member
+  // variables has been explicitly checked and set using nsCOMPtr
+  // for owning pointers and raw COM interface pointers for weak
+  // (ie, non owning) references. If you add any members to this
+  // class, please make the ownership explicit (pinkerton, scc).
+
+  nsCOMPtr<nsIRequest> mDocumentRequest;  // [OWNER] ???compare with document
+
+  nsDocLoader* mParent;  // [WEAK]
+
+  typedef nsAutoTObserverArray<nsListenerInfo, 8> ListenerArray;
+  ListenerArray mListenerInfoList;
+
+  nsCOMPtr<nsILoadGroup> mLoadGroup;
+  // We hold weak refs to all our kids
+  nsTObserverArray<nsDocLoader*> mChildList;
+
+  // The following member variables are related to the new nsIWebProgress
+  // feedback interfaces that travis cooked up.
+  int32_t mProgressStateFlags;
+
+  int64_t mCurrentSelfProgress;
+  int64_t mMaxSelfProgress;
+
+  int64_t mCurrentTotalProgress;
+  int64_t mMaxTotalProgress;
+
+  PLDHashTable mRequestInfoHash;
+  int64_t mCompletedTotalProgress;
+
+  mozilla::LinkedList<nsStatusInfo> mStatusInfoList;
+
+  /*
+   * This flag indicates that the loader is loading a document.  It is set
+   * from the call to LoadDocument(...) until the OnConnectionsComplete(...)
+   * notification is fired...
+   */
+  bool mIsLoadingDocument;
+
+  /* Flag to indicate that we're in the process of restoring a document. */
+  bool mIsRestoringDocument;
+
+  /* Flag to indicate that we're in the process of flushing layout
+     under DocLoaderIsEmpty() and should not do another flush. */
+  bool mDontFlushLayout;
+
+  /* Flag to indicate whether we should consider ourselves as currently
+     flushing layout for the purposes of IsBusy. For example, if Stop has
+     been called then IsBusy should return false even if we are still
+     flushing. */
+  bool mIsFlushingLayout;
+
+  bool mTreatAsBackgroundLoad;
+
+ private:
+  bool mHasFakeOnLoadDispatched;
+
+  bool mIsReadyToHandlePostMessage;
+  /**
+   * This flag indicates that the loader is waiting for completion of
+   * a document.open-triggered "document load".  This is set when
+   * document.open() happens and sets up a new parser and cleared out
+   * when we go to fire our load event or end up with a new document
+   * channel.
+   */
+  bool mDocumentOpenedButNotLoaded;
+
+  bool mNotifyAboutBackgroundRequests;
+
+  static const PLDHashTableOps sRequestInfoHashOps;
+
+  // A list of kids that are in the middle of their onload calls and will let
+  // us know once they're done.  We don't want to fire onload for "normal"
+  // DocLoaderIsEmpty calls (those coming from requests finishing in our
+  // loadgroup) unless this is empty.
+  nsCOMArray<nsIDocumentLoader> mChildrenInOnload;
+
+  int64_t GetMaxTotalProgress();
+
+  nsresult AddRequestInfo(nsIRequest* aRequest);
+  void RemoveRequestInfo(nsIRequest* aRequest);
+  nsRequestInfo* GetRequestInfo(nsIRequest* aRequest) const;
+  void ClearRequestInfoHash();
+  int64_t CalculateMaxProgress();
+  ///    void DumpChannelInfo(void);
+
+  // used to clear our internal progress state between loads...
+  void ClearInternalProgress();
+
+  /**
+   * Used to test whether we might need to fire a load event.  This
+   * can happen when we have a document load going on, or when we've
+   * had document.open() called and haven't fired the corresponding
+   * load event yet.
+   */
+  bool IsBlockingLoadEvent() const {
+    return mIsLoadingDocument || mDocumentOpenedButNotLoaded;
+  }
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsDocLoader, NS_THIS_DOCLOADER_IMPL_CID)
+
+static inline nsISupports* ToSupports(nsDocLoader* aDocLoader) {
+  return static_cast<nsIDocumentLoader*>(aDocLoader);
+}
+
+#endif /* nsDocLoader_h__ */
diff --git a/uriloader/base/nsIContentHandler.idl b/uriloader/base/nsIContentHandler.idl
new file mode 100644
index 0000000000..31ef87a8ba
--- /dev/null
+++ b/uriloader/base/nsIContentHandler.idl
@@ -0,0 +1,35 @@
+/* -*- Mode: C++; tab-width: 2; 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 "nsISupports.idl"
+interface nsIRequest;
+interface nsIInterfaceRequestor;
+
+[scriptable, uuid(49439df2-b3d2-441c-bf62-866bdaf56fd2)]
+interface nsIContentHandler : nsISupports
+{
+  /**
+   * Tells the content handler to take over handling the content. If this
+   * function succeeds, the URI Loader will leave this request alone, ignoring
+   * progress notifications. Failure of this method will cause the request to be
+   * cancelled, unless the error code is NS_ERROR_WONT_HANDLE_CONTENT (see
+   * below).
+   *
+   * @param aWindowContext
+   *        Window context, used to get things like the current nsIDOMWindow
+   *        for this request. May be null.
+   * @param aContentType
+   *        The content type of aRequest
+   * @param aRequest
+   *        A request whose content type is already known.
+   *
+   * @throw NS_ERROR_WONT_HANDLE_CONTENT Indicates that this handler does not
+   *        want to handle this content. A different way for handling this
+   *        content should be tried.
+   */
+  void handleContent(in string aContentType,
+                     in nsIInterfaceRequestor aWindowContext,
+                     in nsIRequest aRequest);
+};
diff --git a/uriloader/base/nsIDocumentLoader.idl b/uriloader/base/nsIDocumentLoader.idl
new file mode 100644
index 0000000000..ae02a827e2
--- /dev/null
+++ b/uriloader/base/nsIDocumentLoader.idl
@@ -0,0 +1,35 @@
+/* -*- Mode: C++; tab-width: 2; 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 "nsISupports.idl"
+interface nsILoadGroup;
+interface nsIChannel;
+interface nsIURI;
+interface nsIWebProgress;
+interface nsIRequest;
+
+/**
+ * An nsIDocumentLoader is an interface responsible for tracking groups of
+ * loads that belong together (images, external scripts, etc) and subdocuments
+ * (<iframe>, <frame>, etc). It is also responsible for sending
+ * nsIWebProgressListener notifications.
+ * XXXbz this interface should go away, we think...
+ */
+[scriptable, uuid(bbe961ee-59e9-42bb-be50-0331979bb79f)]
+interface nsIDocumentLoader : nsISupports
+{
+  // Stop all loads in the loadgroup of this docloader
+  void stop();
+
+  // XXXbz is this needed?  For embedding?  What this does is does is not
+  // defined by this interface!
+  readonly attribute nsISupports container;
+
+  // The loadgroup associated with this docloader
+  readonly attribute nsILoadGroup loadGroup;
+
+  // The defaultLoadRequest of the loadgroup associated with this docloader
+  readonly attribute nsIChannel documentChannel;
+};
diff --git a/uriloader/base/nsITransfer.idl b/uriloader/base/nsITransfer.idl
new file mode 100644
index 0000000000..54c59cd396
--- /dev/null
+++ b/uriloader/base/nsITransfer.idl
@@ -0,0 +1,156 @@
+/* -*- 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 "nsIWebProgressListener2.idl"
+
+interface nsIArray;
+interface nsIURI;
+interface nsICancelable;
+interface nsIMIMEInfo;
+interface nsIFile;
+interface nsIReferrerInfo;
+interface nsIHttpChannel;
+webidl BrowsingContext;
+
+[scriptable, uuid(37ec75d3-97ad-4da8-afaa-eabe5b4afd73)]
+interface nsITransfer : nsIWebProgressListener2 {
+
+    const unsigned long DOWNLOAD_ACCEPTABLE = 0;
+    const unsigned long DOWNLOAD_FORBIDDEN = 1;
+    const unsigned long DOWNLOAD_POTENTIALLY_UNSAFE = 2;
+
+    /**
+     * Initializes the transfer with certain properties.  This function must
+     * be called prior to accessing any properties on this interface.
+     *
+     * @param aSource The source URI of the transfer. Must not be null.
+     *
+     * @param aSourceOriginalURI The original URI of the transfer in case
+     *                           aSource is a blob URL. Can be null.
+     *
+     * @param aTarget The target URI of the transfer. Must not be null.
+     *
+     * @param aDisplayName The user-readable description of the transfer.
+     *                     Can be empty.
+     *
+     * @param aMIMEInfo The MIME info associated with the target,
+     *                  including MIME type and helper app when appropriate.
+     *                  This parameter is optional.
+     *
+     * @param startTime Time when the download started (ie, when the first
+     *                  response from the server was received)
+     *                  XXX presumably wbp and exthandler do this differently
+     *
+     * @param aTempFile The location of a temporary file; i.e. a file in which
+     *                  the received data will be stored, but which is not
+     *                  equal to the target file. (will be moved to the real
+     *                  target by the caller, when the download is finished)
+     *                  May be null.
+     *
+     * @param aCancelable An object that can be used to abort the download.
+     *                    Must not be null.
+     *                    Implementations are expected to hold a strong
+     *                    reference to this object until the download is
+     *                    finished, at which point they should release the
+     *                    reference.
+     *
+     * @param aIsPrivate Used to determine the privacy status of the new transfer.
+     *                   If true, indicates that the transfer was initiated from
+     *                   a source that desires privacy.
+     *
+     * @param aDownloadClassification Indicates wheter the download is unwanted,
+     *                                should be considered dangerous or insecure.
+     *
+     * @param aReferrerInfo The Referrer this download is started with
+     *
+     * @param aOpenDownloadsListOnStart true (default) - Open downloads panel.
+     *                                  false - Only show an icon indicator.
+     *                                  This parameter is optional.
+     */
+    void init(in nsIURI aSource,
+              in nsIURI aSourceOriginalURI,
+              in nsIURI aTarget,
+              in AString aDisplayName,
+              in nsIMIMEInfo aMIMEInfo,
+              in PRTime startTime,
+              in nsIFile aTempFile,
+              in nsICancelable aCancelable,
+              in boolean aIsPrivate,
+              in long aDownloadClassification,
+              in nsIReferrerInfo aReferrerInfo,
+              [optional] in boolean aOpenDownloadsListOnStart);
+
+    /**
+     * Same as init, but allows for passing the browsingContext
+     * which will allow for opening the download with the same
+     * userContextId and auth header.
+     *
+     * @param aBrowsingContext BrowsingContext of the initiating document.
+     *
+     * @param aHandleInternally Set to true if the download should be opened within
+     *                          the browser.
+     * @param aHttpChannel Channel of the initiating document.
+     */
+    void initWithBrowsingContext(in nsIURI aSource,
+                                  in nsIURI aTarget,
+                                    in AString aDisplayName,
+                                    in nsIMIMEInfo aMIMEInfo,
+                                    in PRTime startTime,
+                                    in nsIFile aTempFile,
+                                    in nsICancelable aCancelable,
+                                    in boolean aIsPrivate,
+                                    in long aDownloadClassification,
+                                    in nsIReferrerInfo aReferrerInfo,
+                                    [optional] in boolean aOpenDownloadsListOnStart,
+                                    in BrowsingContext aBrowsingContext,
+                                    in boolean aHandleInternally,
+                                    in nsIHttpChannel aHttpChannel);
+
+
+    /*
+     * Used to notify the transfer object of the hash of the downloaded file.
+     * Must be called on the main thread, only after the download has finished
+     * successfully.
+     * @param aHash The SHA-256 hash in raw bytes of the downloaded file.
+     */
+    void setSha256Hash(in ACString aHash);
+
+    /*
+     * Used to notify the transfer object of the signature of the downloaded
+     * file.  Must be called on the main thread, only after the download has
+     * finished successfully.
+     * @param aSignatureInfo The Array of Array of Array of bytes
+     *        certificates of the downloaded file.
+     */
+    void setSignatureInfo(in Array<Array<Array<uint8_t> > > aSignatureInfo);
+
+    /*
+     * Used to notify the transfer object of the redirects associated with the
+     * channel that terminated in the downloaded file.  Must be called on the
+     * main thread, only after the download has finished successfully.
+     * @param aRedirects The nsIArray of nsIPrincipal of redirected URIs
+     *        associated with the downloaded file.
+     */
+    void setRedirects(in nsIArray aRedirects);
+};
+
+%{C++
+/**
+ * A component with this contract ID will be created each time a download is
+ * started, and nsITransfer::Init will be called on it and an observer will be set.
+ *
+ * Notifications of the download progress will happen via
+ * nsIWebProgressListener/nsIWebProgressListener2.
+ *
+ * INTERFACES THAT MUST BE IMPLEMENTED:
+ *   nsITransfer
+ *   nsIWebProgressListener
+ *   nsIWebProgressListener2
+ *
+ * XXX move this to nsEmbedCID.h once the interfaces (and the contract ID) are
+ * frozen.
+ */
+#define NS_TRANSFER_CONTRACTID "@mozilla.org/transfer;1"
+%}
diff --git a/uriloader/base/nsIURIContentListener.idl b/uriloader/base/nsIURIContentListener.idl
new file mode 100644
index 0000000000..000b878273
--- /dev/null
+++ b/uriloader/base/nsIURIContentListener.idl
@@ -0,0 +1,123 @@
+/* -*- Mode: IDL; 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 "nsISupports.idl"
+
+interface nsIRequest;
+interface nsIStreamListener;
+interface nsIURI;
+
+/**
+ * nsIURIContentListener is an interface used by components which
+ * want to know (and have a chance to handle) a particular content type.
+ * Typical usage scenarios will include running applications which register
+ * a nsIURIContentListener for each of its content windows with the uri
+ * dispatcher service.
+ */
+[scriptable, uuid(10a28f38-32e8-4c63-8aa1-12eaaebc369a)]
+interface nsIURIContentListener : nsISupports
+{
+ /**
+  * Notifies the content listener to hook up an nsIStreamListener capable of
+  * consuming the data stream.
+  *
+  * @param aContentType         Content type of the data.
+  * @param aIsContentPreferred  Indicates whether the content should be
+  *                             preferred by this listener.
+  * @param aRequest             Request that is providing the data.
+  * @param aContentHandler      nsIStreamListener that will consume the data.
+  *                             This should be set to <code>nullptr</code> if
+  *                             this content listener can't handle the content
+  *                             type; in this case, doContent should also fail
+  *                             (i.e., return failure nsresult).
+  *
+  * @return                     <code>true</code> if the load should
+  *                             be aborted and consumer wants to
+  *                             handle the load completely by itself.  This
+  *                             causes the URI Loader do nothing else...
+  *                             <code>false</code> if the URI Loader should
+  *                             continue handling the load and call the
+  *                             returned streamlistener's methods.
+  */
+  boolean doContent(in ACString aContentType,
+                    in boolean aIsContentPreferred,
+                    in nsIRequest aRequest,
+                    out nsIStreamListener aContentHandler);
+
+ /**
+  * When given a uri to dispatch, if the URI is specified as 'preferred
+  * content' then the uri loader tries to find a preferred content handler
+  * for the content type. The thought is that many content listeners may
+  * be able to handle the same content type if they have to. i.e. the mail
+  * content window can handle text/html just like a browser window content
+  * listener. However, if the user clicks on a link with text/html content,
+  * then the browser window should handle that content and not the mail
+  * window where the user may have clicked the link.  This is the difference
+  * between isPreferred and canHandleContent.
+  *
+  * @param aContentType         Content type of the data.
+  * @param aDesiredContentType  Indicates that aContentType must be converted
+  *                             to aDesiredContentType before processing the
+  *                             data.  This causes a stream converted to be
+  *                             inserted into the nsIStreamListener chain.
+  *                             This argument can be <code>nullptr</code> if
+  *                             the content should be consumed directly as
+  *                             aContentType.
+  *
+  * @return                     <code>true</code> if this is a preferred
+  *                             content handler for aContentType;
+  *                             <code>false<code> otherwise.
+  */
+  boolean isPreferred(in string aContentType, out string aDesiredContentType);
+
+ /**
+  * When given a uri to dispatch, if the URI is not specified as 'preferred
+  * content' then the uri loader calls canHandleContent to see if the content
+  * listener is capable of handling the content.
+  *
+  * @param aContentType         Content type of the data.
+  * @param aIsContentPreferred  Indicates whether the content should be
+  *                             preferred by this listener.
+  * @param aDesiredContentType  Indicates that aContentType must be converted
+  *                             to aDesiredContentType before processing the
+  *                             data.  This causes a stream converted to be
+  *                             inserted into the nsIStreamListener chain.
+  *                             This argument can be <code>nullptr</code> if
+  *                             the content should be consumed directly as
+  *                             aContentType.
+  *
+  * @return                     <code>true</code> if the data can be consumed.
+  *                             <code>false</code> otherwise.
+  *
+  * Note: I really envision canHandleContent as a method implemented
+  * by the docshell as the implementation is generic to all doc
+  * shells. The isPreferred decision is a decision made by a top level
+  * application content listener that sits at the top of the docshell
+  * hierarchy.
+  */
+  boolean canHandleContent(in string aContentType,
+                           in boolean aIsContentPreferred,
+                           out string aDesiredContentType);
+
+ /**
+  * The load context associated with a particular content listener.
+  * The URI Loader stores and accesses this value as needed.
+  */
+  attribute nsISupports loadCookie;
+
+ /**
+  * The parent content listener if this particular listener is part of a chain
+  * of content listeners (i.e. a docshell!)
+  *
+  * @note If this attribute is set to an object that implements
+  *       nsISupportsWeakReference, the implementation should get the
+  *       nsIWeakReference and hold that.  Otherwise, the implementation
+  *       should not refcount this interface; it should assume that a non
+  *       null value is always valid.  In that case, the caller is
+  *       responsible for explicitly setting this value back to null if the
+  *       parent content listener is destroyed.
+  */
+  attribute nsIURIContentListener parentContentListener;
+};
diff --git a/uriloader/base/nsIURILoader.idl b/uriloader/base/nsIURILoader.idl
new file mode 100644
index 0000000000..527092c5a6
--- /dev/null
+++ b/uriloader/base/nsIURILoader.idl
@@ -0,0 +1,139 @@
+/* -*- Mode: C++; tab-width: 2; 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 "nsISupports.idl"
+
+interface nsIURIContentListener;
+interface nsIURI;
+interface nsILoadGroup;
+interface nsIProgressEventSink;
+interface nsIChannel;
+interface nsIRequest;
+interface nsIStreamListener;
+interface nsIInputStream;
+interface nsIInterfaceRequestor;
+
+/**
+ * The uri dispatcher is responsible for taking uri's, determining
+ * the content and routing the opened url to the correct content
+ * handler.
+ *
+ * When you encounter a url you want to open, you typically call
+ * openURI, passing it the content listener for the window the uri is
+ * originating from. The uri dispatcher opens the url to discover the
+ * content type. It then gives the content listener first crack at
+ * handling the content. If it doesn't want it, the dispatcher tries
+ * to hand it off one of the registered content listeners. This allows
+ * running applications the chance to jump in and handle the content.
+ *
+ * If that also fails, then the uri dispatcher goes to the registry
+ * looking for the preferred content handler for the content type
+ * of the uri. The content handler may create an app instance
+ * or it may hand the contents off to a platform specific plugin
+ * or helper app. Or it may hand the url off to an OS registered
+ * application.
+ */
+[scriptable, uuid(8762c4e7-be35-4958-9b81-a05685bb516d)]
+interface nsIURILoader : nsISupports
+{
+  /**
+   * @name Flags for opening URIs.
+   */
+  /* @{ */
+  /**
+   * Should the content be displayed in a container that prefers the
+   * content-type, or will any container do.
+   */
+  const unsigned long IS_CONTENT_PREFERRED = 1 << 0;
+  /**
+   * If this flag is set, only the listener of the specified window context will
+   * be considered for content handling; if it refuses the load, an error will
+   * be indicated.
+   */
+  const unsigned long DONT_RETARGET        = 1 << 1;
+  /* @} */
+
+  /**
+   * As applications such as messenger and the browser are instantiated,
+   * they register content listener's with the uri dispatcher corresponding
+   * to content windows within that application.
+   *
+   * Note to self: we may want to optimize things a bit more by requiring
+   * the content types the registered content listener cares about.
+   *
+   * @param aContentListener
+   *        The listener to register. This listener must implement
+   *        nsISupportsWeakReference.
+   *
+   * @see the nsIURILoader class description
+   */
+  void registerContentListener   (in nsIURIContentListener aContentListener);
+  void unRegisterContentListener (in nsIURIContentListener aContentListener);
+
+  /**
+   * OpenURI requires the following parameters.....
+   * @param aChannel
+   *        The channel that should be opened. This must not be asyncOpen'd yet!
+   *        If a loadgroup is set on the channel, it will get replaced with a
+   *        different one.
+   * @param aFlags
+   *        Combination (bitwise OR) of the flags specified above. 0 indicates
+   *        default handling.
+   * @param aWindowContext
+   *        If you are running the url from a doc shell or a web shell, this is
+   *        your window context. If you have a content listener you want to
+   *        give first crack to, the uri loader needs to be able to get it
+   *        from the window context. We will also be using the window context
+   *        to get at the progress event sink interface.
+   *        <b>Must not be null!</b>
+   */
+  void openURI(in nsIChannel aChannel,
+               in unsigned long aFlags,
+               in nsIInterfaceRequestor aWindowContext);
+
+  /**
+   * Loads data from a channel. This differs from openURI in that the channel
+   * may already be opened, and that it returns a stream listener into which the
+   * caller should pump data. The caller is responsible for opening the channel
+   * and pumping the channel's data into the returned stream listener.
+   *
+   * Note: If the channel already has a loadgroup, it will be replaced with the
+   * window context's load group, or null if the context doesn't have one.
+   *
+   * If the window context's nsIURIContentListener refuses the load immediately
+   * (e.g. in nsIURIContentListener::onStartURIOpen), this method will return
+   * NS_ERROR_WONT_HANDLE_CONTENT. At that point, the caller should probably
+   * cancel the channel if it's already open (this method will not cancel the
+   * channel).
+   *
+   * If flags include DONT_RETARGET, and the content listener refuses the load
+   * during onStartRequest (e.g. in canHandleContent/isPreferred), then the
+   * returned stream listener's onStartRequest method will return
+   * NS_ERROR_WONT_HANDLE_CONTENT.
+   *
+   * @param aChannel
+   *        The channel that should be loaded. The channel may already be
+   *        opened. It must not be closed (i.e. this must be called before the
+   *        channel calls onStopRequest on its stream listener).
+   * @param aFlags
+   *        Combination (bitwise OR) of the flags specified above. 0 indicates
+   *        default handling.
+   * @param aWindowContext
+   *        If you are running the url from a doc shell or a web shell, this is
+   *        your window context. If you have a content listener you want to
+   *        give first crack to, the uri loader needs to be able to get it
+   *        from the window context. We will also be using the window context
+   *        to get at the progress event sink interface.
+   *        <b>Must not be null!</b>
+   */
+  nsIStreamListener openChannel(in nsIChannel aChannel,
+                                in unsigned long aFlags,
+                                in nsIInterfaceRequestor aWindowContext);
+
+  /**
+   * Stops an in progress load
+   */
+  void stop(in nsISupports aLoadCookie);
+};
diff --git a/uriloader/base/nsIWebProgress.idl b/uriloader/base/nsIWebProgress.idl
new file mode 100644
index 0000000000..10d6593381
--- /dev/null
+++ b/uriloader/base/nsIWebProgress.idl
@@ -0,0 +1,185 @@
+/* -*- Mode: IDL; tab-width: 4; 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 "nsISupports.idl"
+
+interface mozIDOMWindowProxy;
+interface nsIEventTarget;
+interface nsIRequest;
+interface nsIWebProgressListener;
+webidl BrowsingContext;
+
+/**
+ * The nsIWebProgress interface is used to add or remove nsIWebProgressListener
+ * instances to observe the loading of asynchronous requests (usually in the
+ * context of a DOM window).
+ *
+ * nsIWebProgress instances may be arranged in a parent-child configuration,
+ * corresponding to the parent-child configuration of their respective DOM
+ * windows.  However, in some cases a nsIWebProgress instance may not have an
+ * associated DOM window.  The parent-child relationship of nsIWebProgress
+ * instances is not made explicit by this interface, but the relationship may
+ * exist in some implementations.
+ *
+ * A nsIWebProgressListener instance receives notifications for the
+ * nsIWebProgress instance to which it added itself, and it may also receive
+ * notifications from any nsIWebProgress instances that are children of that
+ * nsIWebProgress instance.
+ */
+[scriptable, builtinclass, uuid(c4d64640-b332-4db6-a2a5-e08566000dc9)]
+interface nsIWebProgress : nsISupports
+{
+  /**
+   * The following flags may be combined to form the aNotifyMask parameter for
+   * the addProgressListener method.  They limit the set of events that are
+   * delivered to an nsIWebProgressListener instance.
+   */
+
+  /**
+   * These flags indicate the state transistions to observe, corresponding to
+   * nsIWebProgressListener::onStateChange.
+   *
+   * NOTIFY_STATE_REQUEST
+   *   Only receive the onStateChange event if the aStateFlags parameter
+   *   includes nsIWebProgressListener::STATE_IS_REQUEST.
+   *
+   * NOTIFY_STATE_DOCUMENT
+   *   Only receive the onStateChange event if the aStateFlags parameter
+   *   includes nsIWebProgressListener::STATE_IS_DOCUMENT.
+   *
+   * NOTIFY_STATE_NETWORK
+   *   Only receive the onStateChange event if the aStateFlags parameter
+   *   includes nsIWebProgressListener::STATE_IS_NETWORK.
+   *
+   * NOTIFY_STATE_WINDOW
+   *   Only receive the onStateChange event if the aStateFlags parameter
+   *   includes nsIWebProgressListener::STATE_IS_WINDOW.
+   *
+   * NOTIFY_STATE_ALL
+   *   Receive all onStateChange events.
+   */
+  const unsigned long NOTIFY_STATE_REQUEST  = 0x00000001;
+  const unsigned long NOTIFY_STATE_DOCUMENT = 0x00000002;
+  const unsigned long NOTIFY_STATE_NETWORK  = 0x00000004;
+  const unsigned long NOTIFY_STATE_WINDOW   = 0x00000008;
+  const unsigned long NOTIFY_STATE_ALL      = 0x0000000f;
+
+  /**
+   * These flags indicate the other events to observe, corresponding to the
+   * other four methods defined on nsIWebProgressListener.
+   *
+   * NOTIFY_PROGRESS
+   *   Receive onProgressChange events.
+   *
+   * NOTIFY_STATUS
+   *   Receive onStatusChange events.
+   *
+   * NOTIFY_SECURITY
+   *   Receive onSecurityChange events.
+   *
+   * NOTIFY_LOCATION
+   *   Receive onLocationChange events.
+   *
+   * NOTIFY_CONTENT_BLOCKING
+   *   Receive onContentBlockingEvent events.
+   *
+   * NOTIFY_REFRESH
+   *   Receive onRefreshAttempted events.
+   *   This is defined on nsIWebProgressListener2.
+   */
+  const unsigned long NOTIFY_PROGRESS         = 0x00000010;
+  const unsigned long NOTIFY_STATUS           = 0x00000020;
+  const unsigned long NOTIFY_SECURITY         = 0x00000040;
+  const unsigned long NOTIFY_LOCATION         = 0x00000080;
+  const unsigned long NOTIFY_REFRESH          = 0x00000100;
+  const unsigned long NOTIFY_CONTENT_BLOCKING = 0x00000200;
+
+  /**
+   * This flag enables all notifications.
+   */
+  const unsigned long NOTIFY_ALL              = 0x000003ff;
+
+  /**
+   * Registers a listener to receive web progress events.
+   *
+   * @param aListener
+   *        The listener interface to be called when a progress event occurs.
+   *        This object must also implement nsISupportsWeakReference.
+   * @param aNotifyMask
+   *        The types of notifications to receive.
+   *
+   * @throw NS_ERROR_INVALID_ARG
+   *        Indicates that aListener was either null or that it does not
+   *        support weak references.
+   * @throw NS_ERROR_FAILURE
+   *        Indicates that aListener was already registered.
+   */
+  void addProgressListener(in nsIWebProgressListener aListener,
+                           in unsigned long aNotifyMask);
+
+  /**
+   * Removes a previously registered listener of progress events.
+   *
+   * @param aListener
+   *        The listener interface previously registered with a call to
+   *        addProgressListener.
+   *
+   * @throw NS_ERROR_FAILURE
+   *        Indicates that aListener was not registered.
+   */
+  void removeProgressListener(in nsIWebProgressListener aListener);
+
+  /**
+   * BrowsingContext associated with this nsIWebProgress instance, or `null` if
+   * there is no BrowsingContext.
+   */
+  [binaryname(BrowsingContextXPCOM)]
+  readonly attribute BrowsingContext browsingContext;
+
+  [noscript,notxpcom,nostdcall] BrowsingContext getBrowsingContext();
+
+  /**
+   * The DOM window associated with this nsIWebProgress instance.
+   *
+   * @throw NS_ERROR_FAILURE
+   *        Indicates that there is no associated DOM window.
+   */
+  readonly attribute mozIDOMWindowProxy DOMWindow;
+
+  /**
+   * Indicates whether DOMWindow.top == DOMWindow.
+   */
+  readonly attribute boolean isTopLevel;
+
+  /**
+   * Indicates whether or not a document is currently being loaded
+   * in the context of this nsIWebProgress instance.
+   */
+  readonly attribute boolean isLoadingDocument;
+
+  /**
+   * Contains a load type as specified by the load* constants in
+   * nsIDocShell:LoadCommand.
+   */
+  readonly attribute unsigned long loadType;
+
+  /**
+   * Main thread event target to which progress updates should be
+   * dispatched. This typically will be a SchedulerEventTarget
+   * corresponding to the tab requesting updates.
+   */
+  attribute nsIEventTarget target;
+
+  /**
+   * The request for the currently loading document. It is null if
+   * isLoadingDocument is false.
+   * Note, the request may not be the actual nsIChannel instance used for
+   * loading, but a dummy RemoteWebProgressRequest. And since redirects are
+   * hidden from the child processes, this may not reflect the complete
+   * redirect state of the load.
+   */
+  readonly attribute nsIRequest documentRequest;
+};
diff --git a/uriloader/base/nsIWebProgressListener.idl b/uriloader/base/nsIWebProgressListener.idl
new file mode 100644
index 0000000000..1af549a7fc
--- /dev/null
+++ b/uriloader/base/nsIWebProgressListener.idl
@@ -0,0 +1,568 @@
+/* -*- Mode: IDL; tab-width: 4; 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 "nsISupports.idl"
+
+interface nsIWebProgress;
+interface nsIRequest;
+interface nsIURI;
+
+/**
+ * The nsIWebProgressListener interface is implemented by clients wishing to
+ * listen in on the progress associated with the loading of asynchronous
+ * requests in the context of a nsIWebProgress instance as well as any child
+ * nsIWebProgress instances.  nsIWebProgress.idl describes the parent-child
+ * relationship of nsIWebProgress instances.
+ */
+[scriptable, uuid(a9df523b-efe2-421e-9d8e-3d7f807dda4c)]
+interface nsIWebProgressListener : nsISupports
+{
+  /**
+   * State Transition Flags
+   *
+   * These flags indicate the various states that requests may transition
+   * through as they are being loaded.  These flags are mutually exclusive.
+   *
+   * For any given request, onStateChange is called once with the STATE_START
+   * flag, zero or more times with the STATE_TRANSFERRING flag or once with the
+   * STATE_REDIRECTING flag, and then finally once with the STATE_STOP flag.
+   * NOTE: For document requests, a second STATE_STOP is generated (see the
+   * description of STATE_IS_WINDOW for more details).
+   *
+   * STATE_START
+   *   This flag indicates the start of a request.  This flag is set when a
+   *   request is initiated.  The request is complete when onStateChange is
+   *   called for the same request with the STATE_STOP flag set.
+   *
+   * STATE_REDIRECTING
+   *   This flag indicates that a request is being redirected.  The request
+   *   passed to onStateChange is the request that is being redirected.  When a
+   *   redirect occurs, a new request is generated automatically to process the
+   *   new request.  Expect a corresponding STATE_START event for the new
+   *   request, and a STATE_STOP for the redirected request.
+   *
+   * STATE_TRANSFERRING
+   *   This flag indicates that data for a request is being transferred to an
+   *   end consumer.  This flag indicates that the request has been targeted,
+   *   and that the user may start seeing content corresponding to the request.
+   *
+   * STATE_NEGOTIATING
+   *   This flag is not used.
+   *
+   * STATE_STOP
+   *   This flag indicates the completion of a request.  The aStatus parameter
+   *   to onStateChange indicates the final status of the request.
+   */
+  const unsigned long STATE_START          = 0x00000001;
+  const unsigned long STATE_REDIRECTING    = 0x00000002;
+  const unsigned long STATE_TRANSFERRING   = 0x00000004;
+  const unsigned long STATE_NEGOTIATING    = 0x00000008;
+  const unsigned long STATE_STOP           = 0x00000010;
+
+
+  /**
+   * State Type Flags
+   *
+   * These flags further describe the entity for which the state transition is
+   * occuring.  These flags are NOT mutually exclusive (i.e., an onStateChange
+   * event may indicate some combination of these flags).
+   *
+   * STATE_IS_REQUEST
+   *   This flag indicates that the state transition is for a request, which
+   *   includes but is not limited to document requests.  (See below for a
+   *   description of document requests.)  Other types of requests, such as
+   *   requests for inline content (e.g., images and stylesheets) are
+   *   considered normal requests.
+   *
+   * STATE_IS_DOCUMENT
+   *   This flag indicates that the state transition is for a document request.
+   *   This flag is set in addition to STATE_IS_REQUEST.  A document request
+   *   supports the nsIChannel interface and its loadFlags attribute includes
+   *   the nsIChannel::LOAD_DOCUMENT_URI flag.
+   *
+   *   A document request does not complete until all requests associated with
+   *   the loading of its corresponding document have completed.  This includes
+   *   other document requests (e.g., corresponding to HTML <iframe> elements).
+   *   The document corresponding to a document request is available via the
+   *   DOMWindow attribute of onStateChange's aWebProgress parameter.
+   *
+   * STATE_IS_NETWORK
+   *   This flag indicates that the state transition corresponds to the start
+   *   or stop of activity in the indicated nsIWebProgress instance.  This flag
+   *   is accompanied by either STATE_START or STATE_STOP, and it may be
+   *   combined with other State Type Flags.
+   *
+   *   Unlike STATE_IS_WINDOW, this flag is only set when activity within the
+   *   nsIWebProgress instance being observed starts or stops.  If activity
+   *   only occurs in a child nsIWebProgress instance, then this flag will be
+   *   set to indicate the start and stop of that activity.
+   *
+   *   For example, in the case of navigation within a single frame of a HTML
+   *   frameset, a nsIWebProgressListener instance attached to the
+   *   nsIWebProgress of the frameset window will receive onStateChange calls
+   *   with the STATE_IS_NETWORK flag set to indicate the start and stop of
+   *   said navigation.  In other words, an observer of an outer window can
+   *   determine when activity, that may be constrained to a child window or
+   *   set of child windows, starts and stops.
+   *
+   * STATE_IS_WINDOW
+   *   This flag indicates that the state transition corresponds to the start
+   *   or stop of activity in the indicated nsIWebProgress instance.  This flag
+   *   is accompanied by either STATE_START or STATE_STOP, and it may be
+   *   combined with other State Type Flags.
+   *
+   *   This flag is similar to STATE_IS_DOCUMENT.  However, when a document
+   *   request completes, two onStateChange calls with STATE_STOP are
+   *   generated.  The document request is passed as aRequest to both calls.
+   *   The first has STATE_IS_REQUEST and STATE_IS_DOCUMENT set, and the second
+   *   has the STATE_IS_WINDOW flag set (and possibly the STATE_IS_NETWORK flag
+   *   set as well -- see above for a description of when the STATE_IS_NETWORK
+   *   flag may be set).  This second STATE_STOP event may be useful as a way
+   *   to partition the work that occurs when a document request completes.
+   *
+   * STATE_IS_REDIRECTED_DOCUMENT
+   *  Same as STATE_IS_DOCUMENT, but sent only after a redirect has occured.
+   *  Introduced in order not to confuse existing code with extra state change
+   *  events. See |nsDocLoader::OnStartRequest| for more info.
+   */
+  const unsigned long STATE_IS_REQUEST     = 0x00010000;
+  const unsigned long STATE_IS_DOCUMENT    = 0x00020000;
+  const unsigned long STATE_IS_NETWORK     = 0x00040000;
+  const unsigned long STATE_IS_WINDOW      = 0x00080000;
+  const unsigned long STATE_IS_REDIRECTED_DOCUMENT = 0x00100000;
+
+  /**
+   * State Modifier Flags
+   *
+   * These flags further describe the transition which is occuring.  These
+   * flags are NOT mutually exclusive (i.e., an onStateChange event may
+   * indicate some combination of these flags).
+   *
+   * STATE_RESTORING
+   *   This flag indicates that the state transition corresponds to the start
+   *   or stop of activity for restoring a previously-rendered presentation.
+   *   As such, there is no actual network activity associated with this
+   *   request, and any modifications made to the document or presentation
+   *   when it was originally loaded will still be present.
+   */
+  const unsigned long STATE_RESTORING      = 0x01000000;
+
+  /**
+   * State Security Flags
+   *
+   * These flags describe the security state reported by a call to the
+   * onSecurityChange method.  These flags are mutually exclusive.
+   *
+   * STATE_IS_INSECURE
+   *   This flag indicates that the data corresponding to the request
+   *   was received over an insecure channel.
+   *
+   * STATE_IS_BROKEN
+   *   This flag indicates an unknown security state.  This may mean that the
+   *   request is being loaded as part of a page in which some content was
+   *   received over an insecure channel.
+   *
+   * STATE_IS_SECURE
+   *   This flag indicates that the data corresponding to the request was
+   *   received over a secure channel.  The degree of security is expressed by
+   *   STATE_SECURE_HIGH, STATE_SECURE_MED, or STATE_SECURE_LOW.
+   */
+  const unsigned long STATE_IS_INSECURE     = 0x00000004;
+  const unsigned long STATE_IS_BROKEN       = 0x00000001;
+  const unsigned long STATE_IS_SECURE       = 0x00000002;
+
+  /**
+   * Mixed active content flags
+   *
+   * NOTE: IF YOU ARE ADDING MORE OF THESE FLAGS, MAKE SURE TO EDIT
+   * nsSecureBrowserUIImpl::CheckForBlockedContent().
+   *
+   * May be set in addition to the State Security Flags, to indicate that
+   * mixed active content has been encountered.
+   *
+   * STATE_BLOCKED_MIXED_ACTIVE_CONTENT
+   *   Mixed active content has been blocked from loading.
+   *
+   * STATE_LOADED_MIXED_ACTIVE_CONTENT
+   *   Mixed active content has been loaded. State should be STATE_IS_BROKEN.
+   */
+  const unsigned long STATE_BLOCKED_MIXED_ACTIVE_CONTENT  = 0x00000010;
+  const unsigned long STATE_LOADED_MIXED_ACTIVE_CONTENT   = 0x00000020;
+
+  /**
+   * Mixed display content flags
+   *
+   * NOTE: IF YOU ARE ADDING MORE OF THESE FLAGS, MAKE SURE TO EDIT
+   * nsSecureBrowserUIImpl::CheckForBlockedContent().
+   *
+   * May be set in addition to the State Security Flags, to indicate that
+   * mixed display content has been encountered.
+   *
+   * STATE_BLOCKED_MIXED_DISPLAY_CONTENT
+   *   Mixed display content has been blocked from loading.
+   *
+   * STATE_LOADED_MIXED_DISPLAY_CONTENT
+   *   Mixed display content has been loaded. State should be STATE_IS_BROKEN.
+   */
+  const unsigned long STATE_BLOCKED_MIXED_DISPLAY_CONTENT = 0x00000100;
+  const unsigned long STATE_LOADED_MIXED_DISPLAY_CONTENT  = 0x00000200;
+
+  /**
+    * State bits for EV == Extended Validation == High Assurance
+    *
+    * These flags describe the level of identity verification
+    * in a call to the onSecurityChange method.
+    *
+    * STATE_IDENTITY_EV_TOPLEVEL
+    *   The topmost document uses an EV cert.
+    *   NOTE: Available since Gecko 1.9
+    */
+
+  const unsigned long STATE_IDENTITY_EV_TOPLEVEL    = 0x00100000;
+
+  /**
+    * Broken state flags
+    *
+    * These flags describe the reason of the broken state.
+    *
+    * STATE_USES_SSL_3
+    *   The topmost document uses SSL 3.0.
+    *
+    * STATE_USES_WEAK_CRYPTO
+    *   The topmost document uses a weak cipher suite such as RC4.
+    *
+    * STATE_CERT_USER_OVERRIDDEN
+    *   The user has added a security exception for the site.
+    */
+  const unsigned long STATE_USES_SSL_3                = 0x01000000;
+  const unsigned long STATE_USES_WEAK_CRYPTO          = 0x02000000;
+  const unsigned long STATE_CERT_USER_OVERRIDDEN      = 0x04000000;
+
+  /**
+   * Content Blocking Event flags
+   *
+   * NOTE: IF YOU ARE ADDING MORE OF THESE FLAGS, MAKE SURE TO EDIT
+   * nsSecureBrowserUIImpl::CheckForBlockedContent() AND UPDATE THE
+   * CORRESPONDING LIST IN ContentBlockingController.java
+   *
+   * These flags describe the reason of cookie jar rejection.
+   *
+   * STATE_BLOCKED_TRACKING_CONTENT
+   *   Tracking content has been blocked from loading.
+   *
+   * STATE_LOADED_LEVEL_1_TRACKING_CONTENT
+   *   Tracking content from the Disconnect Level 1 list has been loaded.
+   *
+   * STATE_LOADED_LEVEL_2_TRACKING_CONTENT
+   *   Tracking content from the Disconnect Level 2 list has been loaded.
+   *
+   * STATE_BLOCKED_FINGERPRINTING_CONTENT
+   *   Fingerprinting content has been blocked from loading.
+   *
+   * STATE_LOADED_FINGERPRINTING_CONTENT
+   *   Fingerprinting content has been loaded.
+   *
+   * STATE_REPLACED_FINGERPRINTING_CONTENT
+   *   Fingerprinting content which should be blocked from loading was replaced with a
+   *   shim.
+   *
+   * STATE_ALLOWED_FINGERPRINTING_CONTENT
+   *   Fingerprinting content which should be blocked from loading was allowed.
+   *
+   * STATE_BLOCKED_CRYPTOMINING_CONTENT
+   *   Cryptomining content has been blocked from loading.
+   *
+   * STATE_LOADED_CRYPTOMINING_CONTENT
+   *   Cryptomining content has been loaded.
+   *
+   * STATE_BLOCKED_UNSAFE_CONTENT
+   *   Content which againts SafeBrowsing list has been blocked from loading.
+   *
+   * STATE_COOKIES_LOADED
+   *   Performed a storage access check, which usually means something like a
+   *   cookie or a storage item was loaded/stored on the current tab.
+   *   Alternatively this could indicate that something in the current tab
+   *   attempted to communicate with its same-origin counterparts in other
+   *   tabs.
+   *
+   * STATE_COOKIES_LOADED_TRACKER
+   *   Similar to STATE_COOKIES_LOADED, but only sent if the subject of the
+   *   action was a third-party tracker when the active cookie policy imposes
+   *   restrictions on such content.
+   *
+   * STATE_COOKIES_LOADED_SOCIALTRACKER
+   *   Similar to STATE_COOKIES_LOADED, but only sent if the subject of the
+   *   action was a third-party social tracker when the active cookie policy
+   *   imposes restrictions on such content.
+   *
+   * STATE_COOKIES_BLOCKED_BY_PERMISSION
+   *   Rejected for custom site permission.
+   *
+   * STATE_COOKIES_BLOCKED_TRACKER
+   *   Rejected because the resource is a tracker and cookie policy doesn't
+   *   allow its loading.
+   *
+   * STATE_COOKIES_BLOCKED_SOCIALTRACKER
+   *   Rejected because the resource is a tracker from a social origin and
+   *   cookie policy doesn't allow its loading.
+   *
+   * STATE_COOKIES_PARTITIONED_FOREIGN
+   *   Rejected because the resource is a third-party and cookie policy forces
+   *   third-party resources to be partitioned.
+   *
+   * STATE_COOKIES_BLOCKED_ALL
+   *   Rejected because cookie policy blocks all cookies.
+   *
+   * STATE_COOKIES_BLOCKED_FOREIGN
+   *   Rejected because cookie policy blocks 3rd party cookies.
+   *
+   * STATE_BLOCKED_SOCIALTRACKING_CONTENT
+   *   SocialTracking content has been blocked from loading.
+   *
+   * STATE_LOADED_SOCIALTRACKING_CONTENT
+   *   SocialTracking content has been loaded.
+   *
+   * STATE_REPLACED_TRACKING_CONTENT
+   *   Tracking content which should be blocked from loading was replaced with a
+   *   shim.
+   *
+   * STATE_ALLOWED_TRACKING_CONTENT
+   *   Tracking content which should be blocked from loading was allowed.
+   *
+   * STATE_BLOCKED_EMAILTRACING_CONTENT
+   *   EmailTracking content has been blocked from loading.
+   *
+   * STATE_LOADED_EMAILTRACKING_LEVEL_1_CONTENT
+   *   EmailTracking content from the Disconnect level 1 has been loaded.
+   *
+   * STATE_LOADED_EMAILTRACKING_LEVEL_2_CONTENT
+   *   EmailTracking content from the Disconnect level 2 has been loaded.
+   */
+  const unsigned long STATE_BLOCKED_TRACKING_CONTENT             = 0x00001000;
+  const unsigned long STATE_LOADED_LEVEL_1_TRACKING_CONTENT      = 0x00002000;
+  const unsigned long STATE_LOADED_LEVEL_2_TRACKING_CONTENT      = 0x00100000;
+  const unsigned long STATE_BLOCKED_FINGERPRINTING_CONTENT       = 0x00000040;
+  const unsigned long STATE_LOADED_FINGERPRINTING_CONTENT        = 0x00000400;
+  const unsigned long STATE_REPLACED_FINGERPRINTING_CONTENT      = 0x08000000;
+  const unsigned long STATE_ALLOWED_FINGERPRINTING_CONTENT       = 0x00000200;
+  const unsigned long STATE_BLOCKED_CRYPTOMINING_CONTENT         = 0x00000800;
+  const unsigned long STATE_LOADED_CRYPTOMINING_CONTENT          = 0x00200000;
+  const unsigned long STATE_BLOCKED_UNSAFE_CONTENT               = 0x00004000;
+  const unsigned long STATE_COOKIES_LOADED                       = 0x00008000;
+  const unsigned long STATE_COOKIES_LOADED_TRACKER               = 0x00040000;
+  const unsigned long STATE_COOKIES_LOADED_SOCIALTRACKER         = 0x00080000;
+  const unsigned long STATE_COOKIES_BLOCKED_BY_PERMISSION        = 0x10000000;
+  const unsigned long STATE_COOKIES_BLOCKED_TRACKER              = 0x20000000;
+  const unsigned long STATE_COOKIES_BLOCKED_SOCIALTRACKER        = 0x01000000;
+  const unsigned long STATE_COOKIES_BLOCKED_ALL                  = 0x40000000;
+  const unsigned long STATE_COOKIES_PARTITIONED_FOREIGN          = 0x80000000;
+  const unsigned long STATE_COOKIES_BLOCKED_FOREIGN              = 0x00000080;
+  const unsigned long STATE_BLOCKED_SOCIALTRACKING_CONTENT       = 0x00010000;
+  const unsigned long STATE_LOADED_SOCIALTRACKING_CONTENT        = 0x00020000;
+  const unsigned long STATE_REPLACED_TRACKING_CONTENT            = 0x00000010;
+  const unsigned long STATE_ALLOWED_TRACKING_CONTENT             = 0x00000020;
+  const unsigned long STATE_BLOCKED_EMAILTRACKING_CONTENT        = 0x00400000;
+  const unsigned long STATE_LOADED_EMAILTRACKING_LEVEL_1_CONTENT = 0x00800000;
+  const unsigned long STATE_LOADED_EMAILTRACKING_LEVEL_2_CONTENT = 0x00000100;
+
+  /**
+   * Flag for HTTPS-Only Mode upgrades
+   *
+   * STATE_HTTPS_ONLY_MODE_UPGRADED
+   *   When a request has been upgraded by HTTPS-Only Mode
+   *
+   * STATE_HTTPS_ONLY_MODE_UPGRADE_FAILED
+   *   When an upgraded request failed.
+   */
+  const unsigned long STATE_HTTPS_ONLY_MODE_UPGRADED        = 0x00400000;
+  const unsigned long STATE_HTTPS_ONLY_MODE_UPGRADE_FAILED  = 0x00800000;
+
+  /**
+   * Notification indicating the state has changed for one of the requests
+   * associated with aWebProgress.
+   *
+   * @param aWebProgress
+   *        The nsIWebProgress instance that fired the notification
+   * @param aRequest
+   *        The nsIRequest that has changed state.
+   * @param aStateFlags
+   *        Flags indicating the new state.  This value is a combination of one
+   *        of the State Transition Flags and one or more of the State Type
+   *        Flags defined above.  Any undefined bits are reserved for future
+   *        use.
+   * @param aStatus
+   *        Error status code associated with the state change.  This parameter
+   *        should be ignored unless aStateFlags includes the STATE_STOP bit.
+   *        The status code indicates success or failure of the request
+   *        associated with the state change.  NOTE: aStatus may be a success
+   *        code even for server generated errors, such as the HTTP 404 error.
+   *        In such cases, the request itself should be queried for extended
+   *        error information (e.g., for HTTP requests see nsIHttpChannel).
+   */
+  void onStateChange(in nsIWebProgress aWebProgress,
+                     in nsIRequest aRequest,
+                     in unsigned long aStateFlags,
+                     in nsresult aStatus);
+
+  /**
+   * Notification that the progress has changed for one of the requests
+   * associated with aWebProgress.  Progress totals are reset to zero when all
+   * requests in aWebProgress complete (corresponding to onStateChange being
+   * called with aStateFlags including the STATE_STOP and STATE_IS_WINDOW
+   * flags).
+   *
+   * @param aWebProgress
+   *        The nsIWebProgress instance that fired the notification.
+   * @param aRequest
+   *        The nsIRequest that has new progress.
+   * @param aCurSelfProgress
+   *        The current progress for aRequest.
+   * @param aMaxSelfProgress
+   *        The maximum progress for aRequest.
+   * @param aCurTotalProgress
+   *        The current progress for all requests associated with aWebProgress.
+   * @param aMaxTotalProgress
+   *        The total progress for all requests associated with aWebProgress.
+   *
+   * NOTE: If any progress value is unknown, or if its value would exceed the
+   * maximum value of type long, then its value is replaced with -1.
+   *
+   * NOTE: If the object also implements nsIWebProgressListener2 and the caller
+   * knows about that interface, this function will not be called. Instead,
+   * nsIWebProgressListener2::onProgressChange64 will be called.
+   */
+  void onProgressChange(in nsIWebProgress aWebProgress,
+                        in nsIRequest aRequest,
+                        in long aCurSelfProgress,
+                        in long aMaxSelfProgress,
+                        in long aCurTotalProgress,
+                        in long aMaxTotalProgress);
+
+  /**
+   * Flags for onLocationChange
+   *
+   * LOCATION_CHANGE_SAME_DOCUMENT
+   *   This flag is on when |aWebProgress| did not load a new document.
+   *   For example, the location change is due to an anchor scroll or a
+   *   pushState/popState/replaceState.
+   *
+   * LOCATION_CHANGE_ERROR_PAGE
+   *   This flag is on when |aWebProgress| redirected from the requested
+   *   contents to an internal page to show error status, such as
+   *   <about:neterror>, <about:certerror> and so on.
+   *
+   *   Generally speaking, |aURI| and |aRequest| are the original data. DOM
+   *   |window.location.href| is also the original location, while
+   *   |document.documentURI| is the redirected location. Sometimes |aURI| is
+   *   <about:blank> and |aRequest| is null when the original data does not
+   +   remain.
+   *
+   *   |aWebProgress| does NOT set this flag when it did not try to load a new
+   *   document. In this case, it should set LOCATION_CHANGE_SAME_DOCUMENT.
+   *
+   * LOCATION_CHANGE_RELOAD
+   *   This flag is on when reloading the current page, either from
+   *   location.reload() or the browser UI.
+   *
+   * LOCATION_CHANGE_HASHCHANGE
+   *   This flag is on for same-document location changes where only the URI's
+   *   reference fragment has changed. This flag implies
+   *   LOCATION_CHANGE_SAME_DOCUMENT.
+   *
+   * LOCATION_CHANGE_SESSION_STORE
+   *   This flag is on for location changes that are the result of the session
+   *   store updating the URI of aWebProgress without actually navigating.
+   */
+  const unsigned long LOCATION_CHANGE_SAME_DOCUMENT   = 0x00000001;
+  const unsigned long LOCATION_CHANGE_ERROR_PAGE      = 0x00000002;
+  const unsigned long LOCATION_CHANGE_RELOAD          = 0x00000004;
+  const unsigned long LOCATION_CHANGE_HASHCHANGE      = 0x00000008;
+  const unsigned long LOCATION_CHANGE_SESSION_STORE   = 0x00000010;
+
+  /**
+   * Called when the location of the window being watched changes.  This is not
+   * when a load is requested, but rather once it is verified that the load is
+   * going to occur in the given window.  For instance, a load that starts in a
+   * window might send progress and status messages for the new site, but it
+   * will not send the onLocationChange until we are sure that we are loading
+   * this new page here.
+   *
+   * @param aWebProgress
+   *        The nsIWebProgress instance that fired the notification.
+   * @param aRequest
+   *        The associated nsIRequest.  This may be null in some cases.
+   * @param aLocation
+   *        The URI of the location that is being loaded.
+   * @param aFlags
+   *        This is a value which explains the situation or the reason why
+   *        the location has changed.
+   */
+  void onLocationChange(in nsIWebProgress aWebProgress,
+                        in nsIRequest aRequest,
+                        in nsIURI aLocation,
+                        [optional] in unsigned long aFlags);
+
+  /**
+   * Notification that the status of a request has changed.  The status message
+   * is intended to be displayed to the user (e.g., in the status bar of the
+   * browser).
+   *
+   * @param aWebProgress
+   *        The nsIWebProgress instance that fired the notification.
+   * @param aRequest
+   *        The nsIRequest that has new status.
+   * @param aStatus
+   *        This value is not an error code.  Instead, it is a numeric value
+   *        that indicates the current status of the request.  This interface
+   *        does not define the set of possible status codes.  NOTE: Some
+   *        status values are defined by nsITransport and nsISocketTransport.
+   * @param aMessage
+   *        Localized text corresponding to aStatus.
+   */
+  void onStatusChange(in nsIWebProgress aWebProgress,
+                      in nsIRequest aRequest,
+                      in nsresult aStatus,
+                      in wstring aMessage);
+
+  /**
+   * Notification called for security progress.  This method will be called on
+   * security transitions (eg HTTP -> HTTPS, HTTPS -> HTTP, FOO -> HTTPS) and
+   * after document load completion.  It might also be called if an error
+   * occurs during network loading.
+   *
+   * @param aWebProgress
+   *        The nsIWebProgress instance that fired the notification.
+   * @param aRequest
+   *        The nsIRequest that has new security state.
+   * @param aState
+   *        A value composed of the Security State Flags and the Security
+   *        Strength Flags listed above.  Any undefined bits are reserved for
+   *        future use.
+   *
+   * NOTE: These notifications will only occur if a security package is
+   * installed.
+   */
+  void onSecurityChange(in nsIWebProgress aWebProgress,
+                        in nsIRequest aRequest,
+                        in unsigned long aState);
+
+  /**
+   * Notification called for content blocking events.  This method will be
+   * called when content gets allowed/blocked for various reasons per the
+   * Content Blocking rules.
+   *
+   * @param aWebProgress
+   *        The nsIWebProgress instance that fired the notification.
+   * @param aRequest
+   *        The nsIRequest that has new security state.
+   * @param aEvent
+   *        A value composed of the Content Blocking Event Flags listed above.
+   *        Any undefined bits are reserved for future use.
+   */
+  void onContentBlockingEvent(in nsIWebProgress aWebProgress,
+                              in nsIRequest aRequest,
+                              in unsigned long aEvent);
+};
diff --git a/uriloader/base/nsIWebProgressListener2.idl b/uriloader/base/nsIWebProgressListener2.idl
new file mode 100644
index 0000000000..a40d9538fb
--- /dev/null
+++ b/uriloader/base/nsIWebProgressListener2.idl
@@ -0,0 +1,69 @@
+/* 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 "nsIWebProgressListener.idl"
+
+/**
+ * An extended version of nsIWebProgressListener.
+ */
+[scriptable, uuid(dde39de0-e4e0-11da-8ad9-0800200c9a66)]
+interface nsIWebProgressListener2 : nsIWebProgressListener {
+  /**
+   * Notification that the progress has changed for one of the requests
+   * associated with aWebProgress.  Progress totals are reset to zero when all
+   * requests in aWebProgress complete (corresponding to onStateChange being
+   * called with aStateFlags including the STATE_STOP and STATE_IS_WINDOW
+   * flags).
+   *
+   * This function is identical to nsIWebProgressListener::onProgressChange,
+   * except that this function supports 64-bit values.
+   *
+   * @param aWebProgress
+   *        The nsIWebProgress instance that fired the notification.
+   * @param aRequest
+   *        The nsIRequest that has new progress.
+   * @param aCurSelfProgress
+   *        The current progress for aRequest.
+   * @param aMaxSelfProgress
+   *        The maximum progress for aRequest.
+   * @param aCurTotalProgress
+   *        The current progress for all requests associated with aWebProgress.
+   * @param aMaxTotalProgress
+   *        The total progress for all requests associated with aWebProgress.
+   *
+   * NOTE: If any progress value is unknown, then its value is replaced with -1.
+   *
+   * @see nsIWebProgressListener2::onProgressChange64
+   */
+  void onProgressChange64(in nsIWebProgress aWebProgress,
+                          in nsIRequest aRequest,
+                          in long long aCurSelfProgress,
+                          in long long aMaxSelfProgress,
+                          in long long aCurTotalProgress,
+                          in long long aMaxTotalProgress);
+
+  /**
+   * Notification that a refresh or redirect has been requested in aWebProgress
+   * For example, via a <meta http-equiv="refresh"> or an HTTP Refresh: header
+   *
+   * @param aWebProgress
+   *        The nsIWebProgress instance that fired the notification.
+   * @param aRefreshURI
+   *        The new URI that aWebProgress has requested redirecting to.
+   * @param aMillis
+   *        The delay (in milliseconds) before refresh.
+   * @param aSameURI
+   *        True if aWebProgress is requesting a refresh of the
+   *        current URI.
+   *        False if aWebProgress is requesting a redirection to
+   *        a different URI.
+   *
+   * @return True if the refresh may proceed.
+   *         False if the refresh should be aborted.
+   */
+  boolean onRefreshAttempted(in nsIWebProgress aWebProgress,
+                             in nsIURI aRefreshURI,
+                             in unsigned long aMillis,
+                             in boolean aSameURI);
+};
diff --git a/uriloader/base/nsURILoader.cpp b/uriloader/base/nsURILoader.cpp
new file mode 100644
index 0000000000..df286e5a73
--- /dev/null
+++ b/uriloader/base/nsURILoader.cpp
@@ -0,0 +1,832 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode:nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sts=2 sw=2 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 "nsURILoader.h"
+#include "nsComponentManagerUtils.h"
+#include "nsIURIContentListener.h"
+#include "nsIContentHandler.h"
+#include "nsILoadGroup.h"
+#include "nsIDocumentLoader.h"
+#include "nsIStreamListener.h"
+#include "nsIURL.h"
+#include "nsIChannel.h"
+#include "nsIInterfaceRequestor.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsIInputStream.h"
+#include "nsIStreamConverterService.h"
+#include "nsIWeakReferenceUtils.h"
+#include "nsIHttpChannel.h"
+#include "netCore.h"
+#include "nsCRT.h"
+#include "nsIDocShell.h"
+#include "nsIThreadRetargetableStreamListener.h"
+#include "nsIChildChannel.h"
+#include "nsExternalHelperAppService.h"
+
+#include "nsString.h"
+#include "nsThreadUtils.h"
+#include "nsReadableUtils.h"
+#include "nsError.h"
+
+#include "nsICategoryManager.h"
+#include "nsCExternalHandlerService.h"
+
+#include "nsNetCID.h"
+
+#include "nsMimeTypes.h"
+
+#include "nsDocLoader.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/IntegerPrintfMacros.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/Unused.h"
+#include "mozilla/StaticPrefs_browser.h"
+#include "mozilla/StaticPrefs_dom.h"
+#include "mozilla/StaticPrefs_general.h"
+#include "nsContentUtils.h"
+
+mozilla::LazyLogModule nsURILoader::mLog("URILoader");
+
+#define LOG(args) MOZ_LOG(nsURILoader::mLog, mozilla::LogLevel::Debug, args)
+#define LOG_ERROR(args) \
+  MOZ_LOG(nsURILoader::mLog, mozilla::LogLevel::Error, args)
+#define LOG_ENABLED() MOZ_LOG_TEST(nsURILoader::mLog, mozilla::LogLevel::Debug)
+
+NS_IMPL_ADDREF(nsDocumentOpenInfo)
+NS_IMPL_RELEASE(nsDocumentOpenInfo)
+
+NS_INTERFACE_MAP_BEGIN(nsDocumentOpenInfo)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIRequestObserver)
+  NS_INTERFACE_MAP_ENTRY(nsIRequestObserver)
+  NS_INTERFACE_MAP_ENTRY(nsIStreamListener)
+  NS_INTERFACE_MAP_ENTRY(nsIThreadRetargetableStreamListener)
+NS_INTERFACE_MAP_END
+
+nsDocumentOpenInfo::nsDocumentOpenInfo(nsIInterfaceRequestor* aWindowContext,
+                                       uint32_t aFlags, nsURILoader* aURILoader)
+    : m_originalContext(aWindowContext),
+      mFlags(aFlags),
+      mURILoader(aURILoader),
+      mDataConversionDepthLimit(
+          mozilla::StaticPrefs::
+              general_document_open_conversion_depth_limit()) {}
+
+nsDocumentOpenInfo::nsDocumentOpenInfo(uint32_t aFlags,
+                                       bool aAllowListenerConversions)
+    : m_originalContext(nullptr),
+      mFlags(aFlags),
+      mURILoader(nullptr),
+      mDataConversionDepthLimit(
+          mozilla::StaticPrefs::general_document_open_conversion_depth_limit()),
+      mAllowListenerConversions(aAllowListenerConversions) {}
+
+nsDocumentOpenInfo::~nsDocumentOpenInfo() {}
+
+nsresult nsDocumentOpenInfo::Prepare() {
+  LOG(("[0x%p] nsDocumentOpenInfo::Prepare", this));
+
+  nsresult rv;
+
+  // ask our window context if it has a uri content listener...
+  m_contentListener = do_GetInterface(m_originalContext, &rv);
+  return rv;
+}
+
+NS_IMETHODIMP nsDocumentOpenInfo::OnStartRequest(nsIRequest* request) {
+  LOG(("[0x%p] nsDocumentOpenInfo::OnStartRequest", this));
+  MOZ_ASSERT(request);
+  if (!request) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  nsresult rv = NS_OK;
+
+  //
+  // Deal with "special" HTTP responses:
+  //
+  // - In the case of a 204 (No Content) or 205 (Reset Content) response, do
+  //   not try to find a content handler.  Return NS_BINDING_ABORTED to cancel
+  //   the request.  This has the effect of ensuring that the DocLoader does
+  //   not try to interpret this as a real request.
+  //
+  nsCOMPtr<nsIHttpChannel> httpChannel(do_QueryInterface(request, &rv));
+
+  if (NS_SUCCEEDED(rv)) {
+    uint32_t responseCode = 0;
+
+    rv = httpChannel->GetResponseStatus(&responseCode);
+
+    if (NS_FAILED(rv)) {
+      LOG_ERROR(("  Failed to get HTTP response status"));
+
+      // behave as in the canceled case
+      return NS_OK;
+    }
+
+    LOG(("  HTTP response status: %d", responseCode));
+
+    if (204 == responseCode || 205 == responseCode) {
+      return NS_BINDING_ABORTED;
+    }
+  }
+
+  //
+  // Make sure that the transaction has succeeded, so far...
+  //
+  nsresult status;
+
+  rv = request->GetStatus(&status);
+
+  NS_ASSERTION(NS_SUCCEEDED(rv), "Unable to get request status!");
+  if (NS_FAILED(rv)) return rv;
+
+  if (NS_FAILED(status)) {
+    LOG_ERROR(("  Request failed, status: 0x%08" PRIX32,
+               static_cast<uint32_t>(status)));
+
+    //
+    // The transaction has already reported an error - so it will be torn
+    // down. Therefore, it is not necessary to return an error code...
+    //
+    return NS_OK;
+  }
+
+  rv = DispatchContent(request);
+
+  LOG(("  After dispatch, m_targetStreamListener: 0x%p, rv: 0x%08" PRIX32,
+       m_targetStreamListener.get(), static_cast<uint32_t>(rv)));
+
+  NS_ASSERTION(
+      NS_SUCCEEDED(rv) || !m_targetStreamListener,
+      "Must not have an m_targetStreamListener with a failure return!");
+
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (m_targetStreamListener)
+    rv = m_targetStreamListener->OnStartRequest(request);
+
+  LOG(("  OnStartRequest returning: 0x%08" PRIX32, static_cast<uint32_t>(rv)));
+
+  return rv;
+}
+
+NS_IMETHODIMP
+nsDocumentOpenInfo::CheckListenerChain() {
+  NS_ASSERTION(NS_IsMainThread(), "Should be on the main thread!");
+  nsresult rv = NS_OK;
+  nsCOMPtr<nsIThreadRetargetableStreamListener> retargetableListener =
+      do_QueryInterface(m_targetStreamListener, &rv);
+  if (retargetableListener) {
+    rv = retargetableListener->CheckListenerChain();
+  }
+  LOG(
+      ("[0x%p] nsDocumentOpenInfo::CheckListenerChain %s listener %p rv "
+       "%" PRIx32,
+       this, (NS_SUCCEEDED(rv) ? "success" : "failure"),
+       (nsIStreamListener*)m_targetStreamListener, static_cast<uint32_t>(rv)));
+  return rv;
+}
+
+NS_IMETHODIMP
+nsDocumentOpenInfo::OnDataAvailable(nsIRequest* request, nsIInputStream* inStr,
+                                    uint64_t sourceOffset, uint32_t count) {
+  // if we have retarged to the end stream listener, then forward the call....
+  // otherwise, don't do anything
+
+  nsresult rv = NS_OK;
+
+  if (m_targetStreamListener)
+    rv = m_targetStreamListener->OnDataAvailable(request, inStr, sourceOffset,
+                                                 count);
+  return rv;
+}
+
+NS_IMETHODIMP nsDocumentOpenInfo::OnStopRequest(nsIRequest* request,
+                                                nsresult aStatus) {
+  LOG(("[0x%p] nsDocumentOpenInfo::OnStopRequest", this));
+
+  if (m_targetStreamListener) {
+    nsCOMPtr<nsIStreamListener> listener(m_targetStreamListener);
+
+    // If this is a multipart stream, we could get another
+    // OnStartRequest after this... reset state.
+    m_targetStreamListener = nullptr;
+    mContentType.Truncate();
+    listener->OnStopRequest(request, aStatus);
+  }
+  mUsedContentHandler = false;
+
+  // Remember...
+  // In the case of multiplexed streams (such as multipart/x-mixed-replace)
+  // these stream listener methods could be called again :-)
+  //
+  return NS_OK;
+}
+
+nsresult nsDocumentOpenInfo::DispatchContent(nsIRequest* request) {
+  LOG(("[0x%p] nsDocumentOpenInfo::DispatchContent for type '%s'", this,
+       mContentType.get()));
+
+  MOZ_ASSERT(!m_targetStreamListener,
+             "Why do we already have a target stream listener?");
+
+  nsresult rv;
+  nsCOMPtr<nsIChannel> aChannel = do_QueryInterface(request);
+  if (!aChannel) {
+    LOG_ERROR(("  Request is not a channel.  Bailing."));
+    return NS_ERROR_FAILURE;
+  }
+
+  constexpr auto anyType = "*/*"_ns;
+  if (mContentType.IsEmpty() || mContentType == anyType) {
+    rv = aChannel->GetContentType(mContentType);
+    if (NS_FAILED(rv)) return rv;
+    LOG(("  Got type from channel: '%s'", mContentType.get()));
+  }
+
+  bool isGuessFromExt =
+      mContentType.LowerCaseEqualsASCII(APPLICATION_GUESS_FROM_EXT);
+  if (isGuessFromExt) {
+    // Reset to application/octet-stream for now; no one other than the
+    // external helper app service should see APPLICATION_GUESS_FROM_EXT.
+    mContentType = APPLICATION_OCTET_STREAM;
+    aChannel->SetContentType(nsLiteralCString(APPLICATION_OCTET_STREAM));
+  }
+
+  // Check whether the data should be forced to be handled externally.  This
+  // could happen because the Content-Disposition header is set so, or, in the
+  // future, because the user has specified external handling for the MIME
+  // type.
+  bool forceExternalHandling = false;
+  uint32_t disposition;
+  rv = aChannel->GetContentDisposition(&disposition);
+
+  if (NS_SUCCEEDED(rv) && disposition == nsIChannel::DISPOSITION_ATTACHMENT) {
+    forceExternalHandling = true;
+  }
+
+  LOG(("  forceExternalHandling: %s", forceExternalHandling ? "yes" : "no"));
+
+  if (forceExternalHandling &&
+      mozilla::StaticPrefs::browser_download_open_pdf_attachments_inline()) {
+    // Check if this is a PDF which should be opened internally. We also handle
+    // octet-streams that look like they might be PDFs based on their extension.
+    bool isPDF = mContentType.LowerCaseEqualsASCII(APPLICATION_PDF);
+    if (!isPDF &&
+        (mContentType.LowerCaseEqualsASCII(APPLICATION_OCTET_STREAM) ||
+         mContentType.IsEmpty())) {
+      nsAutoString flname;
+      aChannel->GetContentDispositionFilename(flname);
+      isPDF = StringEndsWith(flname, u".pdf"_ns);
+      if (!isPDF) {
+        nsCOMPtr<nsIURI> uri;
+        aChannel->GetURI(getter_AddRefs(uri));
+        nsCOMPtr<nsIURL> url(do_QueryInterface(uri));
+        if (url) {
+          nsAutoCString ext;
+          url->GetFileExtension(ext);
+          isPDF = ext.EqualsLiteral("pdf");
+        }
+      }
+    }
+
+    // For a PDF, check if the preference is set that forces attachments to be
+    // opened inline. If so, treat it as a non-attachment by clearing
+    // 'forceExternalHandling' again. This allows it open a PDF directly
+    // instead of downloading it first. It may still end up being handled by
+    // a helper app depending anyway on the later checks.
+    if (isPDF) {
+      nsCOMPtr<nsILoadInfo> loadInfo;
+      aChannel->GetLoadInfo(getter_AddRefs(loadInfo));
+
+      nsCOMPtr<nsIMIMEInfo> mimeInfo;
+
+      nsCOMPtr<nsIMIMEService> mimeSvc(
+          do_GetService(NS_MIMESERVICE_CONTRACTID));
+      NS_ENSURE_TRUE(mimeSvc, NS_ERROR_FAILURE);
+      mimeSvc->GetFromTypeAndExtension(nsLiteralCString(APPLICATION_PDF), ""_ns,
+                                       getter_AddRefs(mimeInfo));
+
+      if (mimeInfo) {
+        int32_t action = nsIMIMEInfo::saveToDisk;
+        mimeInfo->GetPreferredAction(&action);
+
+        bool alwaysAsk = true;
+        mimeInfo->GetAlwaysAskBeforeHandling(&alwaysAsk);
+        forceExternalHandling =
+            alwaysAsk || action != nsIMIMEInfo::handleInternally;
+      }
+    }
+  }
+
+  if (!forceExternalHandling) {
+    //
+    // First step: See whether m_contentListener wants to handle this
+    // content type.
+    //
+    if (TryDefaultContentListener(aChannel)) {
+      LOG(("  Success!  Our default listener likes this type"));
+      // All done here
+      return NS_OK;
+    }
+
+    // If we aren't allowed to try other listeners, just skip through to
+    // trying to convert the data.
+    if (!(mFlags & nsIURILoader::DONT_RETARGET)) {
+      //
+      // Second step: See whether some other registered listener wants
+      // to handle this content type.
+      //
+      int32_t count = mURILoader ? mURILoader->m_listeners.Count() : 0;
+      nsCOMPtr<nsIURIContentListener> listener;
+      for (int32_t i = 0; i < count; i++) {
+        listener = do_QueryReferent(mURILoader->m_listeners[i]);
+        if (listener) {
+          if (TryContentListener(listener, aChannel)) {
+            LOG(("  Found listener registered on the URILoader"));
+            return NS_OK;
+          }
+        } else {
+          // remove from the listener list, reset i and update count
+          mURILoader->m_listeners.RemoveObjectAt(i--);
+          --count;
+        }
+      }
+
+      //
+      // Third step: Try to find an nsIContentHandler for our type.
+      //
+      nsAutoCString handlerContractID(NS_CONTENT_HANDLER_CONTRACTID_PREFIX);
+      handlerContractID += mContentType;
+
+      nsCOMPtr<nsIContentHandler> contentHandler =
+          do_CreateInstance(handlerContractID.get());
+      if (contentHandler) {
+        LOG(("  Content handler found"));
+        // Note that m_originalContext can be nullptr when running this in
+        // the parent process on behalf on a docshell in the content process,
+        // and in that case we only support content handlers that don't need
+        // the context.
+        rv = contentHandler->HandleContent(mContentType.get(),
+                                           m_originalContext, request);
+        // XXXbz returning an error code to represent handling the
+        // content is just bizarre!
+        if (rv != NS_ERROR_WONT_HANDLE_CONTENT) {
+          if (NS_FAILED(rv)) {
+            // The content handler has unexpectedly failed.  Cancel the request
+            // just in case the handler didn't...
+            LOG(("  Content handler failed.  Aborting load"));
+            request->Cancel(rv);
+          } else {
+            LOG(("  Content handler taking over load"));
+            mUsedContentHandler = true;
+          }
+
+          return rv;
+        }
+      }
+    } else {
+      LOG(
+          ("  DONT_RETARGET flag set, so skipped over random other content "
+           "listeners and content handlers"));
+    }
+
+    //
+    // Fourth step: If no listener prefers this type, see if any stream
+    //              converters exist to transform this content type into
+    //              some other.
+    //
+    // Don't do this if the server sent us a MIME type of "*/*" because they saw
+    // it in our Accept header and got confused.
+    // XXXbz have to be careful here; may end up in some sort of bizarre
+    // infinite decoding loop.
+    if (mContentType != anyType) {
+      rv = TryStreamConversion(aChannel);
+      if (NS_SUCCEEDED(rv)) {
+        return NS_OK;
+      }
+    }
+  }
+
+  NS_ASSERTION(!m_targetStreamListener,
+               "If we found a listener, why are we not using it?");
+
+  if (mFlags & nsIURILoader::DONT_RETARGET) {
+    LOG(
+        ("  External handling forced or (listener not interested and no "
+         "stream converter exists), and retargeting disallowed -> aborting"));
+    return NS_ERROR_WONT_HANDLE_CONTENT;
+  }
+
+  // Before dispatching to the external helper app service, check for an HTTP
+  // error page.  If we got one, we don't want to handle it with a helper app,
+  // really.
+  // The WPT a-download-click-404.html requires us to silently handle this
+  // without displaying an error page, so we just return early here.
+  // See bug 1604308 for discussion around what the ideal behaviour is.
+  nsCOMPtr<nsIHttpChannel> httpChannel(do_QueryInterface(request));
+  if (httpChannel) {
+    bool requestSucceeded;
+    rv = httpChannel->GetRequestSucceeded(&requestSucceeded);
+    if (NS_FAILED(rv) || !requestSucceeded) {
+      return NS_OK;
+    }
+  }
+
+  // Fifth step:
+  //
+  // All attempts to dispatch this content have failed.  Just pass it off to
+  // the helper app service.
+  //
+
+  nsCOMPtr<nsIExternalHelperAppService> helperAppService =
+      do_GetService(NS_EXTERNALHELPERAPPSERVICE_CONTRACTID, &rv);
+  if (helperAppService) {
+    LOG(("  Passing load off to helper app service"));
+
+    // Set these flags to indicate that the channel has been targeted and that
+    // we are not using the original consumer.
+    nsLoadFlags loadFlags = 0;
+    request->GetLoadFlags(&loadFlags);
+    request->SetLoadFlags(loadFlags | nsIChannel::LOAD_RETARGETED_DOCUMENT_URI |
+                          nsIChannel::LOAD_TARGETED);
+
+    if (isGuessFromExt || mContentType.IsEmpty()) {
+      mContentType = APPLICATION_GUESS_FROM_EXT;
+      aChannel->SetContentType(nsLiteralCString(APPLICATION_GUESS_FROM_EXT));
+    }
+
+    rv = TryExternalHelperApp(helperAppService, aChannel);
+    if (NS_FAILED(rv)) {
+      request->SetLoadFlags(loadFlags);
+      m_targetStreamListener = nullptr;
+    }
+  }
+
+  NS_ASSERTION(m_targetStreamListener || NS_FAILED(rv),
+               "There is no way we should be successful at this point without "
+               "a m_targetStreamListener");
+  return rv;
+}
+
+nsresult nsDocumentOpenInfo::TryExternalHelperApp(
+    nsIExternalHelperAppService* aHelperAppService, nsIChannel* aChannel) {
+  return aHelperAppService->DoContent(mContentType, aChannel, m_originalContext,
+                                      false, nullptr,
+                                      getter_AddRefs(m_targetStreamListener));
+}
+
+nsresult nsDocumentOpenInfo::ConvertData(nsIRequest* request,
+                                         nsIURIContentListener* aListener,
+                                         const nsACString& aSrcContentType,
+                                         const nsACString& aOutContentType) {
+  LOG(("[0x%p] nsDocumentOpenInfo::ConvertData from '%s' to '%s'", this,
+       PromiseFlatCString(aSrcContentType).get(),
+       PromiseFlatCString(aOutContentType).get()));
+
+  if (mDataConversionDepthLimit == 0) {
+    LOG(
+        ("[0x%p] nsDocumentOpenInfo::ConvertData - reached the recursion "
+         "limit!",
+         this));
+    // This will fall back to external helper app handling.
+    return NS_ERROR_ABORT;
+  }
+
+  MOZ_ASSERT(aSrcContentType != aOutContentType,
+             "ConvertData called when the two types are the same!");
+
+  nsresult rv = NS_OK;
+
+  nsCOMPtr<nsIStreamConverterService> StreamConvService =
+      do_GetService(NS_STREAMCONVERTERSERVICE_CONTRACTID, &rv);
+  if (NS_FAILED(rv)) return rv;
+
+  LOG(("  Got converter service"));
+
+  // When applying stream decoders, it is necessary to "insert" an
+  // intermediate nsDocumentOpenInfo instance to handle the targeting of
+  // the "final" stream or streams.
+  //
+  // For certain content types (ie. multi-part/x-mixed-replace) the input
+  // stream is split up into multiple destination streams.  This
+  // intermediate instance is used to target these "decoded" streams...
+  //
+  RefPtr<nsDocumentOpenInfo> nextLink = Clone();
+
+  LOG(("  Downstream DocumentOpenInfo would be: 0x%p", nextLink.get()));
+
+  // Decrease the conversion recursion limit by one to prevent infinite loops.
+  nextLink->mDataConversionDepthLimit = mDataConversionDepthLimit - 1;
+
+  // Make sure nextLink starts with the contentListener that said it wanted
+  // the results of this decode.
+  nextLink->m_contentListener = aListener;
+  // Also make sure it has to look for a stream listener to pump data into.
+  nextLink->m_targetStreamListener = nullptr;
+
+  // Make sure that nextLink treats the data as aOutContentType when
+  // dispatching; that way even if the stream converters don't change the type
+  // on the channel we will still do the right thing.  If aOutContentType is
+  // */*, that's OK -- that will just indicate to nextLink that it should get
+  // the type off the channel.
+  nextLink->mContentType = aOutContentType;
+
+  // The following call sets m_targetStreamListener to the input end of the
+  // stream converter and sets the output end of the stream converter to
+  // nextLink.  As we pump data into m_targetStreamListener the stream
+  // converter will convert it and pass the converted data to nextLink.
+  return StreamConvService->AsyncConvertData(
+      PromiseFlatCString(aSrcContentType).get(),
+      PromiseFlatCString(aOutContentType).get(), nextLink, request,
+      getter_AddRefs(m_targetStreamListener));
+}
+
+nsresult nsDocumentOpenInfo::TryStreamConversion(nsIChannel* aChannel) {
+  constexpr auto anyType = "*/*"_ns;
+
+  // A empty content type should be treated like the unknown content type.
+  nsCString srcContentType(mContentType);
+  if (srcContentType.IsEmpty()) {
+    srcContentType.AssignLiteral(UNKNOWN_CONTENT_TYPE);
+  }
+
+  nsresult rv =
+      ConvertData(aChannel, m_contentListener, srcContentType, anyType);
+  if (NS_FAILED(rv)) {
+    m_targetStreamListener = nullptr;
+  } else if (m_targetStreamListener) {
+    // We found a converter for this MIME type.  We'll just pump data into
+    // it and let the downstream nsDocumentOpenInfo handle things.
+    LOG(("  Converter taking over now"));
+  }
+  return rv;
+}
+
+bool nsDocumentOpenInfo::TryContentListener(nsIURIContentListener* aListener,
+                                            nsIChannel* aChannel) {
+  LOG(("[0x%p] nsDocumentOpenInfo::TryContentListener; mFlags = 0x%x", this,
+       mFlags));
+
+  MOZ_ASSERT(aListener, "Must have a non-null listener");
+  MOZ_ASSERT(aChannel, "Must have a channel");
+
+  bool listenerWantsContent = false;
+  nsCString typeToUse;
+
+  if (mFlags & nsIURILoader::IS_CONTENT_PREFERRED) {
+    aListener->IsPreferred(mContentType.get(), getter_Copies(typeToUse),
+                           &listenerWantsContent);
+  } else {
+    aListener->CanHandleContent(mContentType.get(), false,
+                                getter_Copies(typeToUse),
+                                &listenerWantsContent);
+  }
+  if (!listenerWantsContent) {
+    LOG(("  Listener is not interested"));
+    return false;
+  }
+
+  if (!typeToUse.IsEmpty() && typeToUse != mContentType) {
+    // Need to do a conversion here.
+
+    nsresult rv = NS_ERROR_NOT_AVAILABLE;
+    if (mAllowListenerConversions) {
+      rv = ConvertData(aChannel, aListener, mContentType, typeToUse);
+    }
+
+    if (NS_FAILED(rv)) {
+      // No conversion path -- we don't want this listener, if we got one
+      m_targetStreamListener = nullptr;
+    }
+
+    LOG(("  Found conversion: %s", m_targetStreamListener ? "yes" : "no"));
+
+    // m_targetStreamListener is now the input end of the converter, and we can
+    // just pump the data in there, if it exists.  If it does not, we need to
+    // try other nsIURIContentListeners.
+    return m_targetStreamListener != nullptr;
+  }
+
+  // At this point, aListener wants data of type mContentType.  Let 'em have
+  // it.  But first, if we are retargeting, set an appropriate flag on the
+  // channel
+  nsLoadFlags loadFlags = 0;
+  aChannel->GetLoadFlags(&loadFlags);
+
+  // Set this flag to indicate that the channel has been targeted at a final
+  // consumer.  This load flag is tested in nsDocLoader::OnProgress.
+  nsLoadFlags newLoadFlags = nsIChannel::LOAD_TARGETED;
+
+  nsCOMPtr<nsIURIContentListener> originalListener =
+      do_GetInterface(m_originalContext);
+  if (originalListener != aListener) {
+    newLoadFlags |= nsIChannel::LOAD_RETARGETED_DOCUMENT_URI;
+  }
+  aChannel->SetLoadFlags(loadFlags | newLoadFlags);
+
+  bool abort = false;
+  bool isPreferred = (mFlags & nsIURILoader::IS_CONTENT_PREFERRED) != 0;
+  nsresult rv =
+      aListener->DoContent(mContentType, isPreferred, aChannel,
+                           getter_AddRefs(m_targetStreamListener), &abort);
+
+  if (NS_FAILED(rv)) {
+    LOG_ERROR(("  DoContent failed"));
+
+    // Unset the RETARGETED_DOCUMENT_URI flag if we set it...
+    aChannel->SetLoadFlags(loadFlags);
+    m_targetStreamListener = nullptr;
+    return false;
+  }
+
+  if (abort) {
+    // Nothing else to do here -- aListener is handling it all.  Make
+    // sure m_targetStreamListener is null so we don't do anything
+    // after this point.
+    LOG(("  Listener has aborted the load"));
+    m_targetStreamListener = nullptr;
+  }
+
+  NS_ASSERTION(abort || m_targetStreamListener,
+               "DoContent returned no listener?");
+
+  // aListener is handling the load from this point on.
+  return true;
+}
+
+bool nsDocumentOpenInfo::TryDefaultContentListener(nsIChannel* aChannel) {
+  if (m_contentListener) {
+    return TryContentListener(m_contentListener, aChannel);
+  }
+  return false;
+}
+
+///////////////////////////////////////////////////////////////////////////////////////////////
+// Implementation of nsURILoader
+///////////////////////////////////////////////////////////////////////////////////////////////
+
+nsURILoader::nsURILoader() {}
+
+nsURILoader::~nsURILoader() {}
+
+NS_IMPL_ADDREF(nsURILoader)
+NS_IMPL_RELEASE(nsURILoader)
+
+NS_INTERFACE_MAP_BEGIN(nsURILoader)
+  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIURILoader)
+  NS_INTERFACE_MAP_ENTRY(nsIURILoader)
+NS_INTERFACE_MAP_END
+
+NS_IMETHODIMP nsURILoader::RegisterContentListener(
+    nsIURIContentListener* aContentListener) {
+  nsresult rv = NS_OK;
+
+  nsWeakPtr weakListener = do_GetWeakReference(aContentListener);
+  NS_ASSERTION(weakListener,
+               "your URIContentListener must support weak refs!\n");
+
+  if (weakListener) m_listeners.AppendObject(weakListener);
+
+  return rv;
+}
+
+NS_IMETHODIMP nsURILoader::UnRegisterContentListener(
+    nsIURIContentListener* aContentListener) {
+  nsWeakPtr weakListener = do_GetWeakReference(aContentListener);
+  if (weakListener) m_listeners.RemoveObject(weakListener);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP nsURILoader::OpenURI(nsIChannel* channel, uint32_t aFlags,
+                                   nsIInterfaceRequestor* aWindowContext) {
+  NS_ENSURE_ARG_POINTER(channel);
+
+  if (LOG_ENABLED()) {
+    nsCOMPtr<nsIURI> uri;
+    channel->GetURI(getter_AddRefs(uri));
+    nsAutoCString spec;
+    uri->GetAsciiSpec(spec);
+    LOG(("nsURILoader::OpenURI for %s", spec.get()));
+  }
+
+  nsCOMPtr<nsIStreamListener> loader;
+  nsresult rv = OpenChannel(channel, aFlags, aWindowContext, false,
+                            getter_AddRefs(loader));
+  if (NS_FAILED(rv)) {
+    if (rv == NS_ERROR_WONT_HANDLE_CONTENT) {
+      // Not really an error, from this method's point of view
+      return NS_OK;
+    }
+  }
+
+  // This method is not complete. Eventually, we should first go
+  // to the content listener and ask them for a protocol handler...
+  // if they don't give us one, we need to go to the registry and get
+  // the preferred protocol handler.
+
+  // But for now, I'm going to let necko do the work for us....
+  rv = channel->AsyncOpen(loader);
+
+  // no content from this load - that's OK.
+  if (rv == NS_ERROR_NO_CONTENT) {
+    LOG(("  rv is NS_ERROR_NO_CONTENT -- doing nothing"));
+    return NS_OK;
+  }
+  return rv;
+}
+
+nsresult nsURILoader::OpenChannel(nsIChannel* channel, uint32_t aFlags,
+                                  nsIInterfaceRequestor* aWindowContext,
+                                  bool aChannelIsOpen,
+                                  nsIStreamListener** aListener) {
+  NS_ASSERTION(channel, "Trying to open a null channel!");
+  NS_ASSERTION(aWindowContext, "Window context must not be null");
+
+  if (LOG_ENABLED()) {
+    nsCOMPtr<nsIURI> uri;
+    channel->GetURI(getter_AddRefs(uri));
+    nsAutoCString spec;
+    uri->GetAsciiSpec(spec);
+    LOG(("nsURILoader::OpenChannel for %s", spec.get()));
+  }
+
+  // we need to create a DocumentOpenInfo object which will go ahead and open
+  // the url and discover the content type....
+  RefPtr<nsDocumentOpenInfo> loader =
+      new nsDocumentOpenInfo(aWindowContext, aFlags, this);
+
+  // Set the correct loadgroup on the channel
+  nsCOMPtr<nsILoadGroup> loadGroup(do_GetInterface(aWindowContext));
+
+  if (!loadGroup) {
+    // XXXbz This context is violating what we'd like to be the new uriloader
+    // api.... Set up a nsDocLoader to handle the loadgroup for this context.
+    // This really needs to go away!
+    nsCOMPtr<nsIURIContentListener> listener(do_GetInterface(aWindowContext));
+    if (listener) {
+      nsCOMPtr<nsISupports> cookie;
+      listener->GetLoadCookie(getter_AddRefs(cookie));
+      if (!cookie) {
+        RefPtr<nsDocLoader> newDocLoader = new nsDocLoader();
+        nsresult rv = newDocLoader->Init();
+        if (NS_FAILED(rv)) return rv;
+        rv = nsDocLoader::AddDocLoaderAsChildOfRoot(newDocLoader);
+        if (NS_FAILED(rv)) return rv;
+        cookie = nsDocLoader::GetAsSupports(newDocLoader);
+        listener->SetLoadCookie(cookie);
+      }
+      loadGroup = do_GetInterface(cookie);
+    }
+  }
+
+  // If the channel is pending, then we need to remove it from its current
+  // loadgroup
+  nsCOMPtr<nsILoadGroup> oldGroup;
+  channel->GetLoadGroup(getter_AddRefs(oldGroup));
+  if (aChannelIsOpen && !SameCOMIdentity(oldGroup, loadGroup)) {
+    // It is important to add the channel to the new group before
+    // removing it from the old one, so that the load isn't considered
+    // done as soon as the request is removed.
+    loadGroup->AddRequest(channel, nullptr);
+
+    if (oldGroup) {
+      oldGroup->RemoveRequest(channel, nullptr, NS_BINDING_RETARGETED);
+    }
+  }
+
+  channel->SetLoadGroup(loadGroup);
+
+  // prepare the loader for receiving data
+  nsresult rv = loader->Prepare();
+  if (NS_SUCCEEDED(rv)) NS_ADDREF(*aListener = loader);
+  return rv;
+}
+
+NS_IMETHODIMP nsURILoader::OpenChannel(nsIChannel* channel, uint32_t aFlags,
+                                       nsIInterfaceRequestor* aWindowContext,
+                                       nsIStreamListener** aListener) {
+  bool pending;
+  if (NS_FAILED(channel->IsPending(&pending))) {
+    pending = false;
+  }
+
+  return OpenChannel(channel, aFlags, aWindowContext, pending, aListener);
+}
+
+NS_IMETHODIMP nsURILoader::Stop(nsISupports* aLoadCookie) {
+  nsresult rv;
+  nsCOMPtr<nsIDocumentLoader> docLoader;
+
+  NS_ENSURE_ARG_POINTER(aLoadCookie);
+
+  docLoader = do_GetInterface(aLoadCookie, &rv);
+  if (docLoader) {
+    rv = docLoader->Stop();
+  }
+  return rv;
+}
diff --git a/uriloader/base/nsURILoader.h b/uriloader/base/nsURILoader.h
new file mode 100644
index 0000000000..2dcba44f76
--- /dev/null
+++ b/uriloader/base/nsURILoader.h
@@ -0,0 +1,219 @@
+/* -*- 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 nsURILoader_h__
+#define nsURILoader_h__
+
+#include "nsCURILoader.h"
+#include "nsISupportsUtils.h"
+#include "nsCOMArray.h"
+#include "nsCOMPtr.h"
+#include "nsIInterfaceRequestor.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsString.h"
+#include "nsIWeakReference.h"
+#include "mozilla/Attributes.h"
+#include "nsIStreamListener.h"
+#include "nsIThreadRetargetableStreamListener.h"
+#include "nsIExternalHelperAppService.h"
+
+#include "mozilla/Logging.h"
+
+class nsDocumentOpenInfo;
+
+class nsURILoader final : public nsIURILoader {
+ public:
+  NS_DECL_NSIURILOADER
+  NS_DECL_ISUPPORTS
+
+  nsURILoader();
+
+ protected:
+  ~nsURILoader();
+
+  /**
+   * Equivalent to nsIURILoader::openChannel, but allows specifying whether the
+   * channel is opened already.
+   */
+  [[nodiscard]] nsresult OpenChannel(nsIChannel* channel, uint32_t aFlags,
+                                     nsIInterfaceRequestor* aWindowContext,
+                                     bool aChannelOpen,
+                                     nsIStreamListener** aListener);
+
+  /**
+   * we shouldn't need to have an owning ref count on registered
+   * content listeners because they are supposed to unregister themselves
+   * when they go away. This array stores weak references
+   */
+  nsCOMArray<nsIWeakReference> m_listeners;
+
+  /**
+   * Logging.  The module is called "URILoader"
+   */
+  static mozilla::LazyLogModule mLog;
+
+  friend class nsDocumentOpenInfo;
+};
+
+/**
+ * The nsDocumentOpenInfo contains the state required when a single
+ * document is being opened in order to discover the content type...
+ * Each instance remains alive until its target URL has been loaded
+ * (or aborted).
+ */
+class nsDocumentOpenInfo : public nsIStreamListener,
+                           public nsIThreadRetargetableStreamListener {
+ public:
+  // Real constructor
+  // aFlags is a combination of the flags on nsIURILoader
+  nsDocumentOpenInfo(nsIInterfaceRequestor* aWindowContext, uint32_t aFlags,
+                     nsURILoader* aURILoader);
+  nsDocumentOpenInfo(uint32_t aFlags, bool aAllowListenerConversions);
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+  /**
+   * Prepares this object for receiving data. The stream
+   * listener methods of this class must not be called before calling this
+   * method.
+   */
+  nsresult Prepare();
+
+  // Call this (from OnStartRequest) to attempt to find an nsIStreamListener to
+  // take the data off our hands.
+  nsresult DispatchContent(nsIRequest* request);
+
+  // Call this if we need to insert a stream converter from aSrcContentType to
+  // aOutContentType into the StreamListener chain.  DO NOT call it if the two
+  // types are the same, since no conversion is needed in that case.
+  nsresult ConvertData(nsIRequest* request, nsIURIContentListener* aListener,
+                       const nsACString& aSrcContentType,
+                       const nsACString& aOutContentType);
+
+  /**
+   * Function to attempt to use aListener to handle the load.  If
+   * true is returned, nothing else needs to be done; if false
+   * is returned, then a different way of handling the load should be
+   * tried.
+   */
+  bool TryContentListener(nsIURIContentListener* aListener,
+                          nsIChannel* aChannel);
+
+  /**
+   * Virtual helper functions for content that we expect to be
+   * overriden when running in the parent process on behalf of
+   * a content process docshell.
+   * We also expect nsIStreamListener functions to be overriden
+   * to add functionality.
+   */
+
+  /**
+   * Attempt to create a steam converter converting from the
+   * current mContentType into something else.
+   * Sets m_targetStreamListener if it succeeds.
+   */
+  virtual nsresult TryStreamConversion(nsIChannel* aChannel);
+
+  /**
+   * Attempt to use the default content listener as our stream
+   * listener.
+   * Sets m_targetStreamListener if it succeeds.
+   */
+  virtual bool TryDefaultContentListener(nsIChannel* aChannel);
+
+  /**
+   * Attempt to pass aChannel onto the external helper app service.
+   * Sets m_targetStreamListener if it succeeds.
+   */
+  virtual nsresult TryExternalHelperApp(
+      nsIExternalHelperAppService* aHelperAppService, nsIChannel* aChannel);
+
+  /**
+   * Create another nsDocumentOpenInfo like this one, so that we can chain
+   * them together when we use a stream converter and don't know what the
+   * converted content type is until the converter outputs OnStartRequest.
+   */
+  virtual nsDocumentOpenInfo* Clone() {
+    return new nsDocumentOpenInfo(m_originalContext, mFlags, mURILoader);
+  }
+
+  // nsIRequestObserver methods:
+  NS_DECL_NSIREQUESTOBSERVER
+
+  // nsIStreamListener methods:
+  NS_DECL_NSISTREAMLISTENER
+
+  // nsIThreadRetargetableStreamListener
+  NS_DECL_NSITHREADRETARGETABLESTREAMLISTENER
+
+ protected:
+  virtual ~nsDocumentOpenInfo();
+
+ protected:
+  /**
+   * The first content listener to try dispatching data to.  Typically
+   * the listener associated with the entity that originated the load.
+   * This can be nullptr when running in the parent process for a content
+   * process docshell.
+   */
+  nsCOMPtr<nsIURIContentListener> m_contentListener;
+
+  /**
+   * The stream listener to forward nsIStreamListener notifications
+   * to.  This is set once the load is dispatched.
+   */
+  nsCOMPtr<nsIStreamListener> m_targetStreamListener;
+
+  /**
+   * A pointer to the entity that originated the load. We depend on getting
+   * things like nsIURIContentListeners, nsIDOMWindows, etc off of it.
+   * This can be nullptr when running in the parent process for a content
+   * process docshell.
+   */
+  nsCOMPtr<nsIInterfaceRequestor> m_originalContext;
+
+  /**
+   * IS_CONTENT_PREFERRED is used for the boolean to pass to CanHandleContent
+   * (also determines whether we use CanHandleContent or IsPreferred).
+   * DONT_RETARGET means that we will only try m_originalContext, no other
+   * listeners.
+   */
+  uint32_t mFlags;
+
+  /**
+   * The type of the data we will be trying to dispatch.
+   */
+  nsCString mContentType;
+
+  /**
+   * Reference to the URILoader service so we can access its list of
+   * nsIURIContentListeners.
+   * This can be nullptr when running in the parent process for a content
+   * process docshell.
+   */
+  RefPtr<nsURILoader> mURILoader;
+
+  /**
+   * Limit of data conversion depth to prevent infinite conversion loops
+   */
+  uint32_t mDataConversionDepthLimit;
+
+  /**
+   * Set to true if OnStartRequest handles the content using an
+   * nsIContentHandler, and the content is consumed despite
+   * m_targetStreamListener being nullptr.
+   */
+  bool mUsedContentHandler = false;
+
+  /**
+   * True if we allow nsIURIContentListeners to return a requested
+   * input typeToUse, and attempt to create a matching stream converter.
+   * This is false when running in the parent process for a content process
+   * docshell
+   */
+  bool mAllowListenerConversions = true;
+};
+
+#endif /* nsURILoader_h__ */