diff --git a/browser/base/content/test/performance/browser_startup_content.js b/browser/base/content/test/performance/browser_startup_content.js
index bb4aee2ca44f..1df6116eaf95 100644
--- a/browser/base/content/test/performance/browser_startup_content.js
+++ b/browser/base/content/test/performance/browser_startup_content.js
@@ -49,6 +49,7 @@ const whitelist = {
     "resource://gre/modules/ActorManagerChild.jsm",
     "resource://gre/modules/E10SUtils.jsm",
     "resource://gre/modules/Readerable.jsm",
+    "resource://gre/modules/WebProgressChild.jsm",
 
     // Telemetry
     "resource://gre/modules/TelemetryController.jsm", // bug 1470339
diff --git a/devtools/client/responsive/browser/tunnel.js b/devtools/client/responsive/browser/tunnel.js
index 868bf4cb0685..599dce68a4cc 100644
--- a/devtools/client/responsive/browser/tunnel.js
+++ b/devtools/client/responsive/browser/tunnel.js
@@ -103,6 +103,7 @@ function tunnelToInnerBrowser(outer, inner) {
 
     onLocationChange: (webProgress, request, location, flags) => {
       if (webProgress && webProgress.isTopLevel) {
+        inner._securityUI = outer._securityUI;
         inner._documentURI = outer._documentURI;
         inner._documentContentType = outer._documentContentType;
         inner._contentTitle = outer._contentTitle;
@@ -116,10 +117,6 @@ function tunnelToInnerBrowser(outer, inner) {
       }
     },
 
-    // We do not need an onSecurityChange handler since the remote security UI
-    // has been copied from the inner (remote) browser to the outer (non-remote)
-    // browser and they share it.
-
     QueryInterface: ChromeUtils.generateQI([
       Ci.nsISupportsWeakReference,
       Ci.nsIWebProgressListener,
@@ -467,6 +464,8 @@ MessageManagerTunnel.prototype = {
     "Link:AddFeed",
     "Link:AddSearch",
     "PageStyle:StyleSheets",
+    // Messages sent to RemoteWebProgress.jsm
+    "Content:SecurityChange",
     // Messages sent to browser.js
     "DOMTitleChanged",
     "ImageDocumentLoaded",
diff --git a/dom/interfaces/base/nsIBrowser.idl b/dom/interfaces/base/nsIBrowser.idl
index bfcf059e6d57..30ecbd82e90b 100644
--- a/dom/interfaces/base/nsIBrowser.idl
+++ b/dom/interfaces/base/nsIBrowser.idl
@@ -5,7 +5,6 @@
 
 interface nsIContentSecurityPolicy;
 interface nsIPrincipal;
-interface nsITransportSecurityInfo;
 interface nsIURI;
 interface nsIWebProgress;
 interface nsIReferrerInfo;
@@ -165,18 +164,4 @@ interface nsIBrowser : nsISupports
                                in boolean aHasRequestContextID,
                                in uint64_t aRequestContextID,
                                in AString aContentType);
-
-  /**
-   * Called by Gecko when a security chang event needs to update the event
-   * state stored in the security UI object stored in the parent process.
-   *
-   * @param aSecurityInfo the transport security information from the content
-   *                      process
-   * @param aState the flags from the OnSecurityChange event that triggered
-   *               this method, as outlined in nsIWebProgressListener
-   * @param aIsSecureContext whether or not the context is secure
-   */
-  void updateSecurityUIForSecurityChange(in nsITransportSecurityInfo aSecurityInfo,
-                                         in uint32_t aState,
-                                         in boolean aIsSecureContext);
 };
diff --git a/dom/ipc/BrowserChild.cpp b/dom/ipc/BrowserChild.cpp
index a704e8eae5e2..e19b71c3ea5b 100644
--- a/dom/ipc/BrowserChild.cpp
+++ b/dom/ipc/BrowserChild.cpp
@@ -526,20 +526,23 @@ nsresult BrowserChild::Init(mozIDOMWindowProxy* aParent,
   nsCOMPtr<nsIDocShell> docShell = do_GetInterface(WebNavigation());
   MOZ_ASSERT(docShell);
 
+  const uint32_t notifyMask =
+      nsIWebProgress::NOTIFY_STATE_ALL | nsIWebProgress::NOTIFY_PROGRESS |
+      nsIWebProgress::NOTIFY_STATUS | nsIWebProgress::NOTIFY_LOCATION |
+      nsIWebProgress::NOTIFY_REFRESH | nsIWebProgress::NOTIFY_CONTENT_BLOCKING;
+
   mStatusFilter = new nsBrowserStatusFilter();
 
   RefPtr<nsIEventTarget> eventTarget =
       TabGroup()->EventTargetFor(TaskCategory::Network);
 
   mStatusFilter->SetTarget(eventTarget);
-  nsresult rv =
-      mStatusFilter->AddProgressListener(this, nsIWebProgress::NOTIFY_ALL);
+  nsresult rv = mStatusFilter->AddProgressListener(this, notifyMask);
   NS_ENSURE_SUCCESS(rv, rv);
 
   {
     nsCOMPtr<nsIWebProgress> webProgress = do_QueryInterface(docShell);
-    rv = webProgress->AddProgressListener(mStatusFilter,
-                                          nsIWebProgress::NOTIFY_ALL);
+    rv = webProgress->AddProgressListener(mStatusFilter, notifyMask);
     NS_ENSURE_SUCCESS(rv, rv);
   }
 
@@ -669,7 +672,6 @@ NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(BrowserChild)
   NS_INTERFACE_MAP_ENTRY(nsISupportsWeakReference)
   NS_INTERFACE_MAP_ENTRY(nsITooltipListener)
   NS_INTERFACE_MAP_ENTRY(nsIWebProgressListener)
-  NS_INTERFACE_MAP_ENTRY(nsIWebProgressListener2)
   NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIBrowserChild)
 NS_INTERFACE_MAP_END
 
@@ -3592,12 +3594,31 @@ NS_IMETHODIMP BrowserChild::OnLocationChange(nsIWebProgress* aWebProgress,
     locationChangeData->charsetAutodetected() =
         docShell->GetCharsetAutodetected();
 
-    locationChangeData->contentPrincipal() = document->NodePrincipal();
-    locationChangeData->contentStoragePrincipal() =
-        document->EffectiveStoragePrincipal();
-    locationChangeData->csp() = document->GetCsp();
-    locationChangeData->contentBlockingAllowListPrincipal() =
+    MOZ_TRY(PrincipalToPrincipalInfo(
+        document->EffectiveStoragePrincipal(),
+        &locationChangeData->contentStoragePrincipal(), false));
+
+    MOZ_TRY(PrincipalToPrincipalInfo(document->NodePrincipal(),
+                                     &locationChangeData->contentPrincipal(),
+                                     false));
+
+    nsIPrincipal* contentBlockingAllowListPrincipal =
+
         document->GetContentBlockingAllowListPrincipal();
+    if (contentBlockingAllowListPrincipal) {
+      PrincipalInfo principalInfo;
+      MOZ_TRY(PrincipalToPrincipalInfo(contentBlockingAllowListPrincipal,
+                                       &principalInfo, false));
+      locationChangeData->contentBlockingAllowListPrincipal() = principalInfo;
+    } else {
+      locationChangeData->contentBlockingAllowListPrincipal() = void_t();
+    }
+
+    if (const nsCOMPtr<nsIContentSecurityPolicy> csp = document->GetCsp()) {
+      locationChangeData->csp().emplace();
+      MOZ_TRY(CSPToCSPInfo(csp, &locationChangeData->csp().ref()));
+    }
+
     locationChangeData->referrerInfo() = document->ReferrerInfo();
     locationChangeData->isSyntheticDocument() = document->IsSyntheticDocument();
 
@@ -3659,59 +3680,8 @@ NS_IMETHODIMP BrowserChild::OnStatusChange(nsIWebProgress* aWebProgress,
 NS_IMETHODIMP BrowserChild::OnSecurityChange(nsIWebProgress* aWebProgress,
                                              nsIRequest* aRequest,
                                              uint32_t aState) {
-  if (!IPCOpen() || !mShouldSendWebProgressEventsToParent) {
-    return NS_OK;
-  }
-
-  Maybe<WebProgressData> webProgressData;
-  RequestData requestData;
-
-  MOZ_TRY(PrepareProgressListenerData(aWebProgress, aRequest, webProgressData,
-                                      requestData));
-
-  Maybe<WebProgressSecurityChangeData> securityChangeData;
-
-  if (aWebProgress && webProgressData->isTopLevel()) {
-    nsCOMPtr<nsIDocShell> docShell = do_GetInterface(WebNavigation());
-    if (!docShell) {
-      return NS_OK;
-    }
-
-    nsCOMPtr<nsITransportSecurityInfo> securityInfo;
-    {
-      nsCOMPtr<nsISecureBrowserUI> securityUI;
-      MOZ_TRY(docShell->GetSecurityUI(getter_AddRefs(securityUI)));
-
-      if (securityUI) {
-        MOZ_TRY(securityUI->GetSecInfo(getter_AddRefs(securityInfo)));
-      }
-    }
-
-    bool isSecureContext = false;
-    {
-      nsCOMPtr<nsPIDOMWindowOuter> outerWindow = do_GetInterface(docShell);
-      if (!outerWindow) {
-        return NS_OK;
-      }
-
-      if (nsPIDOMWindowInner* window = outerWindow->GetCurrentInnerWindow()) {
-        isSecureContext = window->IsSecureContext();
-      } else {
-        return NS_OK;
-      }
-    }
-
-    securityChangeData.emplace();
-    securityChangeData->securityInfo() = securityInfo.forget();
-    securityChangeData->isSecureContext() = isSecureContext;
-  }
-
-  Unused << SendOnSecurityChange(webProgressData, requestData, aState,
-                                 securityChangeData);
-
-  return NS_OK;
+  return NS_ERROR_NOT_IMPLEMENTED;
 }
-
 NS_IMETHODIMP BrowserChild::OnContentBlockingEvent(nsIWebProgress* aWebProgress,
                                                    nsIRequest* aRequest,
                                                    uint32_t aEvent) {
diff --git a/dom/ipc/BrowserParent.cpp b/dom/ipc/BrowserParent.cpp
index 27cb93302593..bb36feeee104 100644
--- a/dom/ipc/BrowserParent.cpp
+++ b/dom/ipc/BrowserParent.cpp
@@ -2497,17 +2497,33 @@ mozilla::ipc::IPCResult BrowserParent::RecvOnLocationChange(
                                                           aCanGoForward);
 
   if (aWebProgressData && aWebProgressData->isTopLevel()) {
+    nsCOMPtr<nsIContentSecurityPolicy> csp;
+    if (aLocationChangeData->csp().isSome()) {
+      csp = CSPInfoToCSP(aLocationChangeData->csp().ref(), nullptr, nullptr);
+    }
+
+    nsCOMPtr<nsIPrincipal> contentPrincipal =
+        PrincipalInfoToPrincipal(aLocationChangeData->contentPrincipal());
+    nsCOMPtr<nsIPrincipal> contentStoragePrincipal = PrincipalInfoToPrincipal(
+        aLocationChangeData->contentStoragePrincipal());
     nsCOMPtr<nsIPrincipal> contentBlockingAllowListPrincipal;
+    if (aLocationChangeData->contentBlockingAllowListPrincipal().type() ==
+        OptionalPrincipalInfo::TPrincipalInfo) {
+      contentBlockingAllowListPrincipal = PrincipalInfoToPrincipal(
+          aLocationChangeData->contentBlockingAllowListPrincipal()
+              .get_PrincipalInfo());
+    }
+    nsCOMPtr<nsIReferrerInfo> referrerInfo =
+        aLocationChangeData->referrerInfo();
+
     Unused << browser->SetIsNavigating(aLocationChangeData->isNavigating());
     Unused << browser->UpdateForLocationChange(
         aLocation, aLocationChangeData->charset(),
         aLocationChangeData->mayEnableCharacterEncodingMenu(),
         aLocationChangeData->charsetAutodetected(),
         aLocationChangeData->documentURI(), aLocationChangeData->title(),
-        aLocationChangeData->contentPrincipal(),
-        aLocationChangeData->contentStoragePrincipal(),
-        aLocationChangeData->contentBlockingAllowListPrincipal(),
-        aLocationChangeData->csp(), aLocationChangeData->referrerInfo(),
+        contentPrincipal, contentStoragePrincipal,
+        contentBlockingAllowListPrincipal, csp, referrerInfo,
         aLocationChangeData->isSyntheticDocument(),
         aWebProgressData->innerDOMWindowID(),
         aLocationChangeData->requestContextID().isSome(),
@@ -2545,35 +2561,6 @@ mozilla::ipc::IPCResult BrowserParent::RecvOnStatusChange(
   return IPC_OK();
 }
 
-mozilla::ipc::IPCResult BrowserParent::RecvOnSecurityChange(
-    const Maybe<WebProgressData>& aWebProgressData,
-    const RequestData& aRequestData, const uint32_t aState,
-    const Maybe<WebProgressSecurityChangeData>& aSecurityChangeData) {
-  nsCOMPtr<nsIBrowser> browser;
-  nsCOMPtr<nsIWebProgress> manager;
-  nsCOMPtr<nsIWebProgressListener> managerAsListener;
-  if (!GetWebProgressListener(getter_AddRefs(browser), getter_AddRefs(manager),
-                              getter_AddRefs(managerAsListener))) {
-    return IPC_OK();
-  }
-
-  nsCOMPtr<nsIWebProgress> webProgress;
-  nsCOMPtr<nsIRequest> request;
-  ReconstructWebProgressAndRequest(manager, aWebProgressData, aRequestData,
-                                   getter_AddRefs(webProgress),
-                                   getter_AddRefs(request));
-
-  if (aWebProgressData && aWebProgressData->isTopLevel()) {
-    Unused << browser->UpdateSecurityUIForSecurityChange(
-        aSecurityChangeData->securityInfo(), aState,
-        aSecurityChangeData->isSecureContext());
-  }
-
-  Unused << managerAsListener->OnSecurityChange(webProgress, request, aState);
-
-  return IPC_OK();
-}
-
 mozilla::ipc::IPCResult BrowserParent::RecvOnContentBlockingEvent(
     const Maybe<WebProgressData>& aWebProgressData,
     const RequestData& aRequestData, const uint32_t& aEvent) {
diff --git a/dom/ipc/BrowserParent.h b/dom/ipc/BrowserParent.h
index dc270c92adfc..503b0b2f846c 100644
--- a/dom/ipc/BrowserParent.h
+++ b/dom/ipc/BrowserParent.h
@@ -311,11 +311,6 @@ class BrowserParent final : public PBrowserParent,
       const RequestData& aRequestData, const nsresult aStatus,
       const nsString& aMessage);
 
-  mozilla::ipc::IPCResult RecvOnSecurityChange(
-      const Maybe<WebProgressData>& aWebProgressData,
-      const RequestData& aRequestData, const uint32_t aState,
-      const Maybe<WebProgressSecurityChangeData>& aSecurityChangeData);
-
   mozilla::ipc::IPCResult RecvOnContentBlockingEvent(
       const Maybe<WebProgressData>& aWebProgressData,
       const RequestData& aRequestData, const uint32_t& aEvent);
diff --git a/dom/ipc/PBrowser.ipdl b/dom/ipc/PBrowser.ipdl
index bcd7ec124622..b031c73a6817 100644
--- a/dom/ipc/PBrowser.ipdl
+++ b/dom/ipc/PBrowser.ipdl
@@ -30,7 +30,6 @@ include PBackgroundSharedTypes;
 
 include "mozilla/GfxMessageUtils.h";
 include "mozilla/layers/LayersMessageUtils.h";
-include "mozilla/ipc/TransportSecurityInfoUtils.h";
 
 using mozilla::gfx::Matrix4x4 from "mozilla/gfx/Matrix.h";
 using mozilla::gfx::MaybeMatrix4x4 from "mozilla/gfx/Matrix.h";
@@ -92,7 +91,6 @@ using mozilla::ScrollAxis from "mozilla/PresShellForwards.h";
 using mozilla::ScrollFlags from "mozilla/PresShellForwards.h";
 using struct InputFormData from "mozilla/dom/SessionStoreMessageUtils.h";
 using struct CollectedInputDataValue from "mozilla/dom/SessionStoreMessageUtils.h";
-using refcounted class nsITransportSecurityInfo from "nsITransportSecurityInfo.h";
 
 namespace mozilla {
 namespace dom {
@@ -144,6 +142,7 @@ struct WebProgressStateChangeData
   nsIURI documentURI;
 };
 
+
 struct WebProgressLocationChangeData
 {
   bool isNavigating;
@@ -154,20 +153,14 @@ struct WebProgressLocationChangeData
   nsString title;
   nsString charset;
   nsIURI documentURI;
-  nsIPrincipal contentPrincipal;
-  nsIPrincipal contentStoragePrincipal;
-  nsIPrincipal contentBlockingAllowListPrincipal;
-  nsIContentSecurityPolicy csp;
+  PrincipalInfo contentPrincipal;
+  PrincipalInfo contentStoragePrincipal;
+  OptionalPrincipalInfo contentBlockingAllowListPrincipal;
+  CSPInfo? csp;
   nsIReferrerInfo referrerInfo;
   uint64_t? requestContextID;
 };
 
-struct WebProgressSecurityChangeData
-{
-  nsITransportSecurityInfo securityInfo;
-  bool isSecureContext;
-};
-
 /**
  * A PBrowser manages a maximal locally connected subtree of BrowsingContexts
  * in a content process.
@@ -607,10 +600,6 @@ parent:
                          RequestData aRequestData, nsresult aStatus,
                          nsString aMessage);
 
-    async OnSecurityChange(WebProgressData? aWebProgressData,
-                           RequestData aRequestData, uint32_t aState,
-                           WebProgressSecurityChangeData? aSecurityChangeData);
-
     async OnContentBlockingEvent(WebProgressData? aWebProgressData,
                                  RequestData aRequestData, uint32_t aEvent);
 
diff --git a/ipc/glue/TransportSecurityInfoUtils.cpp b/ipc/glue/TransportSecurityInfoUtils.cpp
deleted file mode 100644
index a545f7d2808e..000000000000
--- a/ipc/glue/TransportSecurityInfoUtils.cpp
+++ /dev/null
@@ -1,112 +0,0 @@
-/* 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 "TransportSecurityInfoUtils.h"
-
-#include "ipc/IPCMessageUtils.h"
-#include "mozilla/psm/TransportSecurityInfo.h"
-
-namespace IPC {
-
-void ParamTraits<nsITransportSecurityInfo*>::Write(
-    Message* aMsg, nsITransportSecurityInfo* aParam) {
-  bool nonNull = !!aParam;
-  WriteParam(aMsg, nonNull);
-  if (!nonNull) {
-    return;
-  }
-
-  aParam->SerializeToIPC(aMsg);
-}
-
-bool ParamTraits<nsITransportSecurityInfo*>::Read(
-    const Message* aMsg, PickleIterator* aIter,
-    RefPtr<nsITransportSecurityInfo>* aResult) {
-  *aResult = nullptr;
-
-  bool nonNull = false;
-  if (!ReadParam(aMsg, aIter, &nonNull)) {
-    return false;
-  }
-
-  if (!nonNull) {
-    return true;
-  }
-
-  RefPtr<nsITransportSecurityInfo> info =
-      new mozilla::psm::TransportSecurityInfo();
-  if (!info->DeserializeFromIPC(aMsg, aIter)) {
-    return false;
-  }
-
-  *aResult = info.forget();
-  return true;
-}
-
-void ParamTraits<nsIX509Cert*>::Write(Message* aMsg, nsIX509Cert* aParam) {
-  bool nonNull = !!aParam;
-  WriteParam(aMsg, nonNull);
-  if (!nonNull) {
-    return;
-  }
-
-  aParam->SerializeToIPC(aMsg);
-}
-
-bool ParamTraits<nsIX509Cert*>::Read(const Message* aMsg, PickleIterator* aIter,
-                                     RefPtr<nsIX509Cert>* aResult) {
-  *aResult = nullptr;
-
-  bool nonNull = false;
-  if (!ReadParam(aMsg, aIter, &nonNull)) {
-    return false;
-  }
-
-  if (!nonNull) {
-    return true;
-  }
-
-  RefPtr<nsIX509Cert> cert = new nsNSSCertificate();
-  if (!cert->DeserializeFromIPC(aMsg, aIter)) {
-    return false;
-  }
-
-  *aResult = cert.forget();
-  return true;
-}
-
-void ParamTraits<nsIX509CertList*>::Write(Message* aMsg,
-                                          nsIX509CertList* aParam) {
-  bool nonNull = !!aParam;
-  WriteParam(aMsg, nonNull);
-  if (!nonNull) {
-    return;
-  }
-
-  aParam->SerializeToIPC(aMsg);
-}
-
-bool ParamTraits<nsIX509CertList*>::Read(const Message* aMsg,
-                                         PickleIterator* aIter,
-                                         RefPtr<nsIX509CertList>* aResult) {
-  bool nonNull = false;
-  if (!ReadParam(aMsg, aIter, &nonNull)) {
-    return false;
-  }
-
-  if (!nonNull) {
-    *aResult = nullptr;
-    return true;
-  }
-
-  RefPtr<nsIX509CertList> certList = new nsNSSCertList();
-  if (!certList->DeserializeFromIPC(aMsg, aIter)) {
-    return false;
-  }
-
-  *aResult = certList.forget();
-  return true;
-}
-
-}  // namespace IPC
diff --git a/ipc/glue/TransportSecurityInfoUtils.h b/ipc/glue/TransportSecurityInfoUtils.h
deleted file mode 100644
index cfc98d93fb7f..000000000000
--- a/ipc/glue/TransportSecurityInfoUtils.h
+++ /dev/null
@@ -1,36 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-#ifndef mozilla_ipc_TransportSecurityInfoUtils_h
-#define mozilla_ipc_TransportSecurityInfoUtils_h
-
-#include "nsCOMPtr.h"
-#include "nsITransportSecurityInfo.h"
-
-namespace IPC {
-
-template <>
-struct ParamTraits<nsITransportSecurityInfo*> {
-  static void Write(Message* aMsg, nsITransportSecurityInfo* aParam);
-  static bool Read(const Message* aMsg, PickleIterator* aIter,
-                   RefPtr<nsITransportSecurityInfo>* aResult);
-};
-
-template <>
-struct ParamTraits<nsIX509Cert*> {
-  static void Write(Message* aMsg, nsIX509Cert* aCert);
-  static bool Read(const Message* aMsg, PickleIterator* aIter,
-                   RefPtr<nsIX509Cert>* aResult);
-};
-
-template <>
-struct ParamTraits<nsIX509CertList*> {
-  static void Write(Message* aMsg, nsIX509CertList* aCertList);
-  static bool Read(const Message* aMsg, PickleIterator* aIter,
-                   RefPtr<nsIX509CertList>* aResult);
-};
-
-}  // namespace IPC
-
-#endif  // mozilla_ipc_TransportSecurityInfoUtils_h
diff --git a/ipc/glue/moz.build b/ipc/glue/moz.build
index 2e3b283c5eab..3dbf5e17bc8d 100644
--- a/ipc/glue/moz.build
+++ b/ipc/glue/moz.build
@@ -47,7 +47,6 @@ EXPORTS.mozilla.ipc += [
     'Shmem.h',
     'TaskFactory.h',
     'Transport.h',
-    'TransportSecurityInfoUtils.h',
     'URIUtils.h',
     'WindowsMessageLoop.h',
 ]
@@ -168,7 +167,6 @@ UNIFIED_SOURCES += [
     'SharedMemory.cpp',
     'Shmem.cpp',
     'StringUtil.cpp',
-    'TransportSecurityInfoUtils.cpp',
     'URIUtils.cpp',
 ]
 
diff --git a/netwerk/socket/nsITransportSecurityInfo.idl b/netwerk/socket/nsITransportSecurityInfo.idl
index 6b5feb177345..989e5842d5e8 100644
--- a/netwerk/socket/nsITransportSecurityInfo.idl
+++ b/netwerk/socket/nsITransportSecurityInfo.idl
@@ -9,16 +9,6 @@
 interface nsIX509Cert;
 interface nsIX509CertList;
 
-%{ C++
-namespace IPC {
-  class Message;
-}
-class PickleIterator;
-%}
-
-[ptr] native IpcMessagePtr(IPC::Message);
-[ptr] native PickleIteratorPtr(PickleIterator);
-
 [builtinclass, scriptable, uuid(216112d3-28bc-4671-b057-f98cc09ba1ea)]
 interface nsITransportSecurityInfo : nsISupports {
     readonly attribute unsigned long securityState;
@@ -81,10 +71,4 @@ interface nsITransportSecurityInfo : nsISupports {
      */
     [must_use]
     readonly attribute boolean isExtendedValidation;
-
-    [notxpcom, noscript]
-    void SerializeToIPC(in IpcMessagePtr aMsg);
-
-    [notxpcom, noscript]
-    bool DeserializeFromIPC([const] in IpcMessagePtr aMsg, in PickleIteratorPtr aIter);
 };
diff --git a/security/apps/moz.build b/security/apps/moz.build
index 8946c7546a7a..ad3fa4e3386d 100644
--- a/security/apps/moz.build
+++ b/security/apps/moz.build
@@ -12,8 +12,6 @@ UNIFIED_SOURCES += [
     'AppTrustDomain.cpp',
 ]
 
-include('/ipc/chromium/chromium-config.mozbuild')
-
 FINAL_LIBRARY = 'xul'
 
 LOCAL_INCLUDES += [
diff --git a/security/certverifier/moz.build b/security/certverifier/moz.build
index ad8aa12dd2d4..f4df7a2fb8ff 100644
--- a/security/certverifier/moz.build
+++ b/security/certverifier/moz.build
@@ -55,8 +55,6 @@ CXXFLAGS += [
     '-Wno-unused-parameter',
 ]
 
-include('/ipc/chromium/chromium-config.mozbuild')
-
 FINAL_LIBRARY = 'xul'
 
 if CONFIG['CC_TYPE'] == 'clang-cl':
diff --git a/security/certverifier/tests/gtest/moz.build b/security/certverifier/tests/gtest/moz.build
index 5b33fc1f9968..2945788989c1 100644
--- a/security/certverifier/tests/gtest/moz.build
+++ b/security/certverifier/tests/gtest/moz.build
@@ -13,6 +13,4 @@ LOCAL_INCLUDES += [
     '/security/manager/ssl',
 ]
 
-include('/ipc/chromium/chromium-config.mozbuild')
-
 FINAL_LIBRARY = 'xul-gtest'
diff --git a/security/manager/ssl/TransportSecurityInfo.cpp b/security/manager/ssl/TransportSecurityInfo.cpp
index dd3e12a19d41..4734774bb2ff 100644
--- a/security/manager/ssl/TransportSecurityInfo.cpp
+++ b/security/manager/ssl/TransportSecurityInfo.cpp
@@ -8,7 +8,6 @@
 
 #include "DateTimeFormat.h"
 #include "PSMRunnable.h"
-#include "ipc/IPCMessageUtils.h"
 #include "mozilla/Casting.h"
 #include "nsComponentManagerUtils.h"
 #include "nsIArray.h"
@@ -158,8 +157,6 @@ TransportSecurityInfo::GetInterface(const nsIID& uuid, void** result) {
   }
 static NS_DEFINE_CID(kTransportSecurityInfoMagic, TRANSPORTSECURITYINFOMAGIC);
 
-// NB: Any updates (except disk-only fields) must be kept in sync with
-//     |SerializeToIPC|.
 NS_IMETHODIMP
 TransportSecurityInfo::Write(nsIObjectOutputStream* aStream) {
   nsresult rv = aStream->WriteID(kTransportSecurityInfoMagic);
@@ -384,8 +381,6 @@ nsresult TransportSecurityInfo::ReadSSLStatus(nsIObjectInputStream* aStream) {
   return rv;
 }
 
-// NB: Any updates (except disk-only fields) must be kept in sync with
-//     |DeserializeFromIPC|.
 NS_IMETHODIMP
 TransportSecurityInfo::Read(nsIObjectInputStream* aStream) {
   nsID id;
@@ -547,64 +542,6 @@ TransportSecurityInfo::Read(nsIObjectInputStream* aStream) {
 
 #undef CHILD_DIAGNOSTIC_ASSERT
 
-void TransportSecurityInfo::SerializeToIPC(IPC::Message* aMsg) {
-  MutexAutoLock guard(mMutex);
-
-  int32_t errorCode = static_cast<int32_t>(mErrorCode);
-
-  WriteParam(aMsg, mSecurityState);
-  WriteParam(aMsg, errorCode);
-  WriteParam(aMsg, mServerCert);
-  WriteParam(aMsg, mCipherSuite);
-  WriteParam(aMsg, mProtocolVersion);
-  WriteParam(aMsg, mIsDomainMismatch);
-  WriteParam(aMsg, mIsNotValidAtThisTime);
-  WriteParam(aMsg, mIsUntrusted);
-  WriteParam(aMsg, mIsEV);
-  WriteParam(aMsg, mHasIsEVStatus);
-  WriteParam(aMsg, mHaveCipherSuiteAndProtocol);
-  WriteParam(aMsg, mHaveCertErrorBits);
-  WriteParam(aMsg, mCertificateTransparencyStatus);
-  WriteParam(aMsg, mKeaGroup);
-  WriteParam(aMsg, mSignatureSchemeName);
-  WriteParam(aMsg, mSucceededCertChain);
-  WriteParam(aMsg, mFailedCertChain);
-}
-
-bool TransportSecurityInfo::DeserializeFromIPC(const IPC::Message* aMsg,
-                                               PickleIterator* aIter) {
-  MutexAutoLock guard(mMutex);
-
-  int32_t errorCode = 0;
-
-  if (!ReadParam(aMsg, aIter, &mSecurityState) ||
-      !ReadParam(aMsg, aIter, &errorCode) ||
-      !ReadParam(aMsg, aIter, &mServerCert) ||
-      !ReadParam(aMsg, aIter, &mCipherSuite) ||
-      !ReadParam(aMsg, aIter, &mProtocolVersion) ||
-      !ReadParam(aMsg, aIter, &mIsDomainMismatch) ||
-      !ReadParam(aMsg, aIter, &mIsNotValidAtThisTime) ||
-      !ReadParam(aMsg, aIter, &mIsUntrusted) ||
-      !ReadParam(aMsg, aIter, &mIsEV) ||
-      !ReadParam(aMsg, aIter, &mHasIsEVStatus) ||
-      !ReadParam(aMsg, aIter, &mHaveCipherSuiteAndProtocol) ||
-      !ReadParam(aMsg, aIter, &mHaveCertErrorBits) ||
-      !ReadParam(aMsg, aIter, &mCertificateTransparencyStatus) ||
-      !ReadParam(aMsg, aIter, &mKeaGroup) ||
-      !ReadParam(aMsg, aIter, &mSignatureSchemeName) ||
-      !ReadParam(aMsg, aIter, &mSucceededCertChain) ||
-      !ReadParam(aMsg, aIter, &mFailedCertChain)) {
-    return false;
-  }
-
-  mErrorCode = static_cast<PRErrorCode>(errorCode);
-  if (mErrorCode != 0) {
-    mCanceled = true;
-  }
-
-  return true;
-}
-
 NS_IMETHODIMP
 TransportSecurityInfo::GetInterfaces(nsTArray<nsIID>& array) {
   array.Clear();
diff --git a/security/manager/ssl/TransportSecurityInfo.h b/security/manager/ssl/TransportSecurityInfo.h
index 5a08495a13df..c20d5fdc7eb1 100644
--- a/security/manager/ssl/TransportSecurityInfo.h
+++ b/security/manager/ssl/TransportSecurityInfo.h
@@ -14,14 +14,13 @@
 #include "mozilla/BasePrincipal.h"
 #include "mozilla/Mutex.h"
 #include "mozilla/RefPtr.h"
-#include "mozilla/ipc/TransportSecurityInfoUtils.h"
-#include "mozpkix/pkixtypes.h"
 #include "nsDataHashtable.h"
 #include "nsIClassInfo.h"
 #include "nsIInterfaceRequestor.h"
 #include "nsITransportSecurityInfo.h"
 #include "nsNSSCertificate.h"
 #include "nsString.h"
+#include "mozpkix/pkixtypes.h"
 
 namespace mozilla {
 namespace psm {
diff --git a/security/manager/ssl/moz.build b/security/manager/ssl/moz.build
index a4b6ad838da4..9d43a3840408 100644
--- a/security/manager/ssl/moz.build
+++ b/security/manager/ssl/moz.build
@@ -84,7 +84,6 @@ EXPORTS.mozilla += [
 
 EXPORTS.mozilla.psm += [
     'PSMContentListener.h',
-    'TransportSecurityInfo.h',
 ]
 
 EXPORTS.ipc += [
diff --git a/security/manager/ssl/nsIX509Cert.idl b/security/manager/ssl/nsIX509Cert.idl
index 70bae2d246eb..a637acb226ec 100644
--- a/security/manager/ssl/nsIX509Cert.idl
+++ b/security/manager/ssl/nsIX509Cert.idl
@@ -12,18 +12,10 @@ interface nsIASN1Object;
 interface nsICertVerificationListener;
 
 %{ C++
-namespace IPC {
-  class Message;
-}
-class PickleIterator;
-
  /* forward declaration */
  typedef struct CERTCertificateStr CERTCertificate;
 %}
-
 [ptr] native CERTCertificatePtr(CERTCertificate);
-[ptr] native IpcMessagePtr(IPC::Message);
-[ptr] native PickleIteratorPtr(PickleIterator);
 
 /**
  * This represents a X.509 certificate.
@@ -243,10 +235,4 @@ interface nsIX509Cert : nsISupports {
    */
   [must_use]
   void markForPermDeletion();
-
-  [notxpcom, noscript]
-  void SerializeToIPC(in IpcMessagePtr aMsg);
-
-  [notxpcom, noscript]
-  bool DeserializeFromIPC([const] in IpcMessagePtr aMsg, in PickleIteratorPtr aIter);
 };
diff --git a/security/manager/ssl/nsIX509CertList.idl b/security/manager/ssl/nsIX509CertList.idl
index bd87f419c612..40518b93dbf1 100644
--- a/security/manager/ssl/nsIX509CertList.idl
+++ b/security/manager/ssl/nsIX509CertList.idl
@@ -8,16 +8,9 @@ interface nsISimpleEnumerator;
 interface nsIX509Cert;
 
 %{C++
-namespace IPC {
-  class Message;
-}
-class PickleIterator;
 class nsNSSCertList;
 %}
-
 [ptr] native nsNSSCertListPtr(nsNSSCertList);
-[ptr] native IpcMessagePtr(IPC::Message);
-[ptr] native PickleIteratorPtr(PickleIterator);
 
 [scriptable, builtinclass, uuid(ae74cda5-cd2f-473f-96f5-f0b7fff62c68)]
 interface nsIX509CertList : nsISupports {
@@ -49,11 +42,6 @@ interface nsIX509CertList : nsISupports {
   [must_use]
   ACString asPKCS7Blob();
 
-  [notxpcom, noscript]
-  void SerializeToIPC(in IpcMessagePtr aMsg);
-
-  [notxpcom, noscript]
-  bool DeserializeFromIPC([const] in IpcMessagePtr aMsg, in PickleIteratorPtr aIter);
 };
 
 %{C++
diff --git a/security/manager/ssl/nsNSSCertificate.cpp b/security/manager/ssl/nsNSSCertificate.cpp
index 3cf77db9b035..52996b1c7411 100644
--- a/security/manager/ssl/nsNSSCertificate.cpp
+++ b/security/manager/ssl/nsNSSCertificate.cpp
@@ -941,8 +941,6 @@ nsNSSCertList::AsPKCS7Blob(/*out*/ nsACString& result) {
   return NS_OK;
 }
 
-// NB: Any updates (except disk-only fields) must be kept in sync with
-//     |SerializeToIPC|.
 NS_IMETHODIMP
 nsNSSCertList::Write(nsIObjectOutputStream* aStream) {
   // Write the length of the list
@@ -967,8 +965,6 @@ nsNSSCertList::Write(nsIObjectOutputStream* aStream) {
   return rv;
 }
 
-// NB: Any updates (except disk-only fields) must be kept in sync with
-//     |DeserializeFromIPC|.
 NS_IMETHODIMP
 nsNSSCertList::Read(nsIObjectInputStream* aStream) {
   uint32_t certListLen;
@@ -996,35 +992,6 @@ nsNSSCertList::Read(nsIObjectInputStream* aStream) {
   return NS_OK;
 }
 
-void nsNSSCertList::SerializeToIPC(IPC::Message* aMsg) {
-  const size_t certCount = static_cast<size_t>(mCerts.size());
-  WriteParam(aMsg, certCount);
-
-  for (const auto& certRef : mCerts) {
-    RefPtr<nsIX509Cert> cert = nsNSSCertificate::Create(certRef.get());
-    MOZ_RELEASE_ASSERT(cert);
-
-    WriteParam(aMsg, cert);
-  }
-}
-
-bool nsNSSCertList::DeserializeFromIPC(const IPC::Message* aMsg,
-                                       PickleIterator* aIter) {
-  size_t count = 0;
-  if (!ReadParam(aMsg, aIter, &count)) {
-    return false;
-  }
-
-  for (size_t i = 0; i < count; i++) {
-    RefPtr<nsIX509Cert> cert;
-    if (!ReadParam(aMsg, aIter, &cert) || !cert || NS_FAILED(AddCert(cert))) {
-      return false;
-    }
-  }
-
-  return true;
-}
-
 NS_IMETHODIMP
 nsNSSCertList::GetEnumerator(nsISimpleEnumerator** _retval) {
   nsCOMPtr<nsISimpleEnumerator> enumerator(new nsNSSCertListEnumerator(mCerts));
@@ -1230,8 +1197,6 @@ nsNSSCertListEnumerator::GetNext(nsISupports** _retval) {
   return NS_OK;
 }
 
-// NB: Any updates (except disk-only fields) must be kept in sync with
-//     |SerializeToIPC|.
 NS_IMETHODIMP
 nsNSSCertificate::Write(nsIObjectOutputStream* aStream) {
   NS_ENSURE_STATE(mCert);
@@ -1248,8 +1213,6 @@ nsNSSCertificate::Write(nsIObjectOutputStream* aStream) {
       AsBytes(MakeSpan(mCert->derCert.data, mCert->derCert.len)));
 }
 
-// NB: Any updates (except disk-only fields) must be kept in sync with
-//     |DeserializeFromIPC|.
 NS_IMETHODIMP
 nsNSSCertificate::Read(nsIObjectInputStream* aStream) {
   NS_ENSURE_STATE(!mCert);
@@ -1280,45 +1243,6 @@ nsNSSCertificate::Read(nsIObjectInputStream* aStream) {
   return NS_OK;
 }
 
-void nsNSSCertificate::SerializeToIPC(IPC::Message* aMsg) {
-  bool hasCert = static_cast<bool>(mCert);
-  WriteParam(aMsg, hasCert);
-
-  if (!hasCert) {
-    return;
-  }
-
-  const nsDependentCSubstring certBytes(
-      reinterpret_cast<char*>(mCert->derCert.data), mCert->derCert.len);
-
-  WriteParam(aMsg, certBytes);
-}
-
-bool nsNSSCertificate::DeserializeFromIPC(const IPC::Message* aMsg,
-                                          PickleIterator* aIter) {
-  bool hasCert = false;
-  if (!ReadParam(aMsg, aIter, &hasCert)) {
-    return false;
-  }
-
-  if (!hasCert) {
-    return true;
-  }
-
-  nsCString derBytes;
-  if (!ReadParam(aMsg, aIter, &derBytes)) {
-    return false;
-  }
-
-  if (derBytes.Length() == 0) {
-    return false;
-  }
-
-  // NSS accepts a |char*| here, but doesn't modify the contents of the array
-  // and casts it back to an |unsigned char*|.
-  return InitFromDER(const_cast<char*>(derBytes.get()), derBytes.Length());
-}
-
 NS_IMETHODIMP
 nsNSSCertificate::GetInterfaces(nsTArray<nsIID>& array) {
   array.Clear();
diff --git a/toolkit/content/browser-child.js b/toolkit/content/browser-child.js
index 3663406ab76b..7e759390e1c9 100644
--- a/toolkit/content/browser-child.js
+++ b/toolkit/content/browser-child.js
@@ -10,6 +10,12 @@ ChromeUtils.defineModuleGetter(
   "resource://gre/modules/BrowserUtils.jsm"
 );
 
+const { WebProgressChild } = ChromeUtils.import(
+  "resource://gre/modules/WebProgressChild.jsm"
+);
+
+this.WebProgress = new WebProgressChild(this);
+
 try {
   docShell
     .QueryInterface(Ci.nsIInterfaceRequestor)
diff --git a/toolkit/content/widgets/browser-custom-element.js b/toolkit/content/widgets/browser-custom-element.js
index 98b1ce21cb68..149bbebc3799 100644
--- a/toolkit/content/widgets/browser-custom-element.js
+++ b/toolkit/content/widgets/browser-custom-element.js
@@ -1264,6 +1264,8 @@
         this.messageManager.addMessageListener("DOMTitleChanged", this);
         this.messageManager.addMessageListener("ImageDocumentLoaded", this);
 
+        // browser-child messages, such as Content:LocationChange, are handled in
+        // RemoteWebProgress, ensure it is loaded and ready.
         let jsm = "resource://gre/modules/RemoteWebProgress.jsm";
         let { RemoteWebProgressManager } = ChromeUtils.import(jsm, {});
 
@@ -1512,16 +1514,6 @@
       }
     }
 
-    updateSecurityUIForSecurityChange(aSecurityInfo, aState, aIsSecureContext) {
-      if (this.isRemoteBrowser && this.messageManager) {
-        // Invoking this getter triggers the generation of the underlying object,
-        // which we need to access with ._securityUI, because .securityUI returns
-        // a wrapper that makes _update inaccessible.
-        void this.securityUI;
-        this._securityUI._update(aSecurityInfo, aState, aIsSecureContext);
-      }
-    }
-
     updateSecurityUIForContentBlockingEvent(aEvent) {
       if (this.isRemoteBrowser && this.messageManager) {
         // Invoking this getter triggers the generation of the underlying object,
diff --git a/toolkit/modules/RemoteWebProgress.jsm b/toolkit/modules/RemoteWebProgress.jsm
index a4e781196edb..2606eb7fa978 100644
--- a/toolkit/modules/RemoteWebProgress.jsm
+++ b/toolkit/modules/RemoteWebProgress.jsm
@@ -5,11 +5,17 @@
 
 var EXPORTED_SYMBOLS = ["RemoteWebProgressManager"];
 
+const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
 const RemoteWebProgress = Components.Constructor(
   "@mozilla.org/dom/remote-web-progress;1",
   "nsIRemoteWebProgress",
   "init"
 );
+const RemoteWebProgressRequest = Components.Constructor(
+  "@mozilla.org/dom/remote-web-progress-request;1",
+  "nsIRemoteWebProgressRequest",
+  "init"
+);
 
 class RemoteWebProgressManager {
   constructor(aBrowser) {
@@ -23,7 +29,16 @@ class RemoteWebProgressManager {
   }
 
   swapBrowser(aBrowser) {
+    if (this._messageManager) {
+      this._messageManager.removeMessageListener(
+        "Content:SecurityChange",
+        this
+      );
+    }
+
     this._browser = aBrowser;
+    this._messageManager = aBrowser.messageManager;
+    this._messageManager.addMessageListener("Content:SecurityChange", this);
   }
 
   swapListeners(aOtherRemoteWebProgressManager) {
@@ -54,6 +69,20 @@ class RemoteWebProgressManager {
     );
   }
 
+  _fixSecInfo(aSecInfo) {
+    let deserialized = null;
+    if (aSecInfo) {
+      let helper = Cc["@mozilla.org/network/serialization-helper;1"].getService(
+        Ci.nsISerializationHelper
+      );
+
+      deserialized = helper.deserializeObject(aSecInfo);
+      deserialized.QueryInterface(Ci.nsITransportSecurityInfo);
+    }
+
+    return deserialized;
+  }
+
   setCurrentURI(aURI) {
     // This function is simpler than nsDocShell::SetCurrentURI since
     // it doesn't have to deal with child docshells.
@@ -154,6 +183,56 @@ class RemoteWebProgressManager {
       aEvent
     );
   }
+
+  receiveMessage(aMessage) {
+    let json = aMessage.json;
+    let webProgress = null;
+    let isTopLevel = json.webProgress && json.webProgress.isTopLevel;
+    // The top-level WebProgress is always the same, but because we don't
+    // really have a concept of subframes/content we always create a new object
+    // for those.
+    if (json.webProgress) {
+      webProgress = isTopLevel
+        ? this._topLevelWebProgress
+        : new RemoteWebProgress(this, isTopLevel);
+      webProgress.update(
+        json.webProgress.DOMWindowID,
+        0,
+        json.webProgress.loadType,
+        json.webProgress.isLoadingDocument
+      );
+      webProgress.QueryInterface(Ci.nsIWebProgress);
+    }
+
+    // The WebProgressRequest object however is always dynamic.
+    let request = null;
+    if (json.requestURI) {
+      request = new RemoteWebProgressRequest(
+        Services.io.newURI(json.requestURI),
+        Services.io.newURI(json.originalRequestURI)
+      );
+      request = request.QueryInterface(Ci.nsIRequest);
+    }
+
+    switch (aMessage.name) {
+      case "Content:SecurityChange":
+        let state = json.state;
+
+        if (isTopLevel) {
+          let secInfo = this._fixSecInfo(json.secInfo);
+          let isSecureContext = json.isSecureContext;
+
+          // Invoking this getter triggers the generation of the underlying object,
+          // which we need to access with ._securityUI, because .securityUI returns
+          // a wrapper that makes _update inaccessible.
+          void this._browser.securityUI;
+          this._browser._securityUI._update(secInfo, state, isSecureContext);
+        }
+
+        this.onSecurityChange(webProgress, request, state);
+        break;
+    }
+  }
 }
 
 RemoteWebProgressManager.prototype.QueryInterface = ChromeUtils.generateQI([
diff --git a/toolkit/modules/WebProgressChild.jsm b/toolkit/modules/WebProgressChild.jsm
new file mode 100644
index 000000000000..c711d2657ac2
--- /dev/null
+++ b/toolkit/modules/WebProgressChild.jsm
@@ -0,0 +1,110 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 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/. */
+"use strict";
+
+var EXPORTED_SYMBOLS = ["WebProgressChild"];
+
+const { XPCOMUtils } = ChromeUtils.import(
+  "resource://gre/modules/XPCOMUtils.jsm"
+);
+
+XPCOMUtils.defineLazyServiceGetter(
+  this,
+  "serializationHelper",
+  "@mozilla.org/network/serialization-helper;1",
+  "nsISerializationHelper"
+);
+
+class WebProgressChild {
+  constructor(mm) {
+    this.mm = mm;
+
+    // NOTIFY_PROGRESS, NOTIFY_STATE_ALL, NOTIFY_STATUS, NOTIFY_LOCATION, NOTIFY_REFRESH, and
+    // NOTIFY_CONTENT_BLOCKING are handled by PBrowser.
+    let notifyCode =
+      Ci.nsIWebProgress.NOTIFY_ALL &
+      ~Ci.nsIWebProgress.NOTIFY_STATE_ALL &
+      ~Ci.nsIWebProgress.NOTIFY_PROGRESS &
+      ~Ci.nsIWebProgress.NOTIFY_STATUS &
+      ~Ci.nsIWebProgress.NOTIFY_LOCATION &
+      ~Ci.nsIWebProgress.NOTIFY_REFRESH &
+      ~Ci.nsIWebProgress.NOTIFY_CONTENT_BLOCKING;
+
+    this._filter = Cc[
+      "@mozilla.org/appshell/component/browser-status-filter;1"
+    ].createInstance(Ci.nsIWebProgress);
+    this._filter.addProgressListener(this, notifyCode);
+    this._filter.target = this.mm.tabEventTarget;
+
+    let webProgress = this.mm.docShell
+      .QueryInterface(Ci.nsIInterfaceRequestor)
+      .getInterface(Ci.nsIWebProgress);
+    webProgress.addProgressListener(this._filter, notifyCode);
+  }
+
+  _requestSpec(aRequest, aPropertyName) {
+    if (!aRequest || !(aRequest instanceof Ci.nsIChannel)) {
+      return null;
+    }
+    return aRequest[aPropertyName].spec;
+  }
+
+  _setupJSON(aWebProgress, aRequest) {
+    if (aWebProgress) {
+      let domWindowID = null;
+      try {
+        domWindowID = aWebProgress.DOMWindowID;
+      } catch (e) {
+        // The DOM Window ID getters above may throw if the inner or outer
+        // windows aren't created yet or are destroyed at the time we're making
+        // this call but that isn't fatal so ignore the exceptions here.
+      }
+
+      aWebProgress = {
+        isTopLevel: aWebProgress.isTopLevel,
+        isLoadingDocument: aWebProgress.isLoadingDocument,
+        loadType: aWebProgress.loadType,
+        DOMWindowID: domWindowID,
+      };
+    }
+
+    return {
+      webProgress: aWebProgress || null,
+      requestURI: this._requestSpec(aRequest, "URI"),
+      originalRequestURI: this._requestSpec(aRequest, "originalURI"),
+    };
+  }
+
+  _send(name, data) {
+    this.mm.sendAsyncMessage(name, data);
+  }
+
+  getSecInfoAsString() {
+    let secInfo = this.mm.docShell.securityUI.secInfo;
+    if (secInfo) {
+      return serializationHelper.serializeToString(secInfo);
+    }
+
+    return null;
+  }
+
+  onSecurityChange(aWebProgress, aRequest, aState) {
+    let json = this._setupJSON(aWebProgress, aRequest);
+
+    json.state = aState;
+
+    if (aWebProgress.isTopLevel) {
+      json.secInfo = this.getSecInfoAsString();
+      json.isSecureContext = this.mm.content.isSecureContext;
+    }
+
+    this._send("Content:SecurityChange", json);
+  }
+}
+
+WebProgressChild.prototype.QueryInterface = ChromeUtils.generateQI([
+  "nsIWebProgressListener",
+  "nsISupportsWeakReference",
+]);
diff --git a/toolkit/modules/moz.build b/toolkit/modules/moz.build
index 97ac31fb87c8..951c65bc661f 100644
--- a/toolkit/modules/moz.build
+++ b/toolkit/modules/moz.build
@@ -229,6 +229,7 @@ EXTRA_JS_MODULES += [
     'Troubleshoot.jsm',
     'UpdateUtils.jsm',
     'WebChannel.jsm',
+    'WebProgressChild.jsm',
     'ZipUtils.jsm',
 ]