--- a/netwerk/base/src/PrivateBrowsingChannel.h
+++ b/netwerk/base/src/PrivateBrowsingChannel.h
@@ -6,16 +6,18 @@
 
 #ifndef mozilla_net_PrivateBrowsingChannel_h__
 #define mozilla_net_PrivateBrowsingChannel_h__
 
 #include "nsIPrivateBrowsingChannel.h"
 #include "nsCOMPtr.h"
 #include "nsILoadGroup.h"
 #include "nsILoadContext.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsIInterfaceRequestor.h"
 
 namespace mozilla {
 namespace net {
 
 template <class Channel>
 class PrivateBrowsingChannel : public nsIPrivateBrowsingChannel
 {
 public:
@@ -51,29 +53,45 @@ public:
       NS_ENSURE_ARG_POINTER(aResult);
       *aResult = mPrivateBrowsingOverriden;
       if (mPrivateBrowsingOverriden) {
           *aValue = mPrivateBrowsing;
       }
       return NS_OK;
   }
 
-  bool CanSetCallbacks() const
+  bool CanSetCallbacks(nsIInterfaceRequestor* aCallbacks) const
   {
       // Make sure that the private bit override flag is not set.
       // This is a fatal error in debug builds, and a runtime error in release
       // builds.
+      if (!aCallbacks) {
+          return true;
+      }
+      nsCOMPtr<nsILoadContext> loadContext = do_GetInterface(aCallbacks);
+      if (!loadContext) {
+          return true;
+      }
       MOZ_ASSERT(!mPrivateBrowsingOverriden);
       return !mPrivateBrowsingOverriden;
   }
 
-  bool CanSetLoadGroup() const
+  bool CanSetLoadGroup(nsILoadGroup* aLoadGroup) const
   {
-      // We can set a load group whenever we can set a callback
-      return CanSetCallbacks();
+      // Make sure that the private bit override flag is not set.
+      // This is a fatal error in debug builds, and a runtime error in release
+      // builds.
+      if (!aLoadGroup) {
+          return true;
+      }
+      nsCOMPtr<nsIInterfaceRequestor> callbacks;
+      aLoadGroup->GetNotificationCallbacks(getter_AddRefs(callbacks));
+      // From this point on, we just hand off the work to CanSetCallbacks,
+      // because the logic is exactly the same.
+      return CanSetCallbacks(callbacks);
   }
 
 protected:
   bool mPrivateBrowsingOverriden;
   bool mPrivateBrowsing;
 };
 
 }

--- a/netwerk/protocol/ftp/FTPChannelChild.cpp
+++ b/netwerk/protocol/ftp/FTPChannelChild.cpp
@@ -545,27 +545,27 @@ FTPChannelChild::CompleteRedirectSetup(n
   // listeners or load group observers canceled us, let the parent handle it
   // and send it back to us naturally.
   return NS_OK;
 }
 
 NS_IMETHODIMP
 FTPChannelChild::SetNotificationCallbacks(nsIInterfaceRequestor* aCallbacks)
 {
-  if (!CanSetCallbacks()) {
+  if (!CanSetCallbacks(aCallbacks)) {
     return NS_ERROR_FAILURE;
   }
 
   return nsBaseChannel::SetNotificationCallbacks(aCallbacks);
 }
 
 NS_IMETHODIMP
 FTPChannelChild::SetLoadGroup(nsILoadGroup * aLoadGroup)
 {
-  if (!CanSetLoadGroup()) {
+  if (!CanSetLoadGroup(aLoadGroup)) {
     return NS_ERROR_FAILURE;
   }
 
   return nsBaseChannel::SetLoadGroup(aLoadGroup);
 }
 
 } // namespace net
 } // namespace mozilla

--- a/netwerk/protocol/ftp/nsFTPChannel.cpp
+++ b/netwerk/protocol/ftp/nsFTPChannel.cpp
@@ -217,24 +217,24 @@ nsFtpChannel::GetFTPEventSink(nsCOMPtr<n
         }
     }
     aResult = mFTPEventSink;
 }
 
 NS_IMETHODIMP
 nsFtpChannel::SetNotificationCallbacks(nsIInterfaceRequestor* aCallbacks)
 {
-  if (!CanSetCallbacks()) {
+  if (!CanSetCallbacks(aCallbacks)) {
     return NS_ERROR_FAILURE;
   }
 
   return nsBaseChannel::SetNotificationCallbacks(aCallbacks);
 }
 
 NS_IMETHODIMP
 nsFtpChannel::SetLoadGroup(nsILoadGroup * aLoadGroup)
 {
-  if (!CanSetLoadGroup()) {
+  if (!CanSetLoadGroup(aLoadGroup)) {
     return NS_ERROR_FAILURE;
   }
 
   return nsBaseChannel::SetLoadGroup(aLoadGroup);
 }

--- a/netwerk/protocol/http/HttpBaseChannel.cpp
+++ b/netwerk/protocol/http/HttpBaseChannel.cpp
@@ -184,17 +184,17 @@ HttpBaseChannel::GetLoadGroup(nsILoadGro
   *aLoadGroup = mLoadGroup;
   NS_IF_ADDREF(*aLoadGroup);
   return NS_OK;
 }
 
 NS_IMETHODIMP
 HttpBaseChannel::SetLoadGroup(nsILoadGroup *aLoadGroup)
 {
-  if (!CanSetLoadGroup()) {
+  if (!CanSetLoadGroup(aLoadGroup)) {
     return NS_ERROR_FAILURE;
   }
 
   mLoadGroup = aLoadGroup;
   mProgressSink = nullptr;
   mPrivateBrowsing = NS_UsePrivateBrowsing(this);
   return NS_OK;
 }
@@ -268,17 +268,17 @@ HttpBaseChannel::GetNotificationCallback
   *aCallbacks = mCallbacks;
   NS_IF_ADDREF(*aCallbacks);
   return NS_OK;
 }
 
 NS_IMETHODIMP
 HttpBaseChannel::SetNotificationCallbacks(nsIInterfaceRequestor *aCallbacks)
 {
-  if (!CanSetCallbacks()) {
+  if (!CanSetCallbacks(aCallbacks)) {
     return NS_ERROR_FAILURE;
   }
 
   mCallbacks = aCallbacks;
   mProgressSink = nullptr;
 
   mPrivateBrowsing = NS_UsePrivateBrowsing(this);
   return NS_OK;

--- a/netwerk/protocol/wyciwyg/WyciwygChannelChild.cpp
+++ b/netwerk/protocol/wyciwyg/WyciwygChannelChild.cpp
@@ -380,17 +380,17 @@ WyciwygChannelChild::GetLoadGroup(nsILoa
 {
   *aLoadGroup = mLoadGroup;
   NS_IF_ADDREF(*aLoadGroup);
   return NS_OK;
 }
 NS_IMETHODIMP
 WyciwygChannelChild::SetLoadGroup(nsILoadGroup * aLoadGroup)
 {
-  if (!CanSetLoadGroup()) {
+  if (!CanSetLoadGroup(aLoadGroup)) {
     return NS_ERROR_FAILURE;
   }
 
   mLoadGroup = aLoadGroup;
   NS_QueryNotificationCallbacks(mCallbacks,
                                 mLoadGroup,
                                 NS_GET_IID(nsIProgressEventSink),
                                 getter_AddRefs(mProgressSink));
@@ -466,17 +466,17 @@ WyciwygChannelChild::GetNotificationCall
 {
   *aCallbacks = mCallbacks;
   NS_IF_ADDREF(*aCallbacks);
   return NS_OK;
 }
 NS_IMETHODIMP
 WyciwygChannelChild::SetNotificationCallbacks(nsIInterfaceRequestor * aCallbacks)
 {
-  if (!CanSetCallbacks()) {
+  if (!CanSetCallbacks(aCallbacks)) {
     return NS_ERROR_FAILURE;
   }
 
   mCallbacks = aCallbacks;
   NS_QueryNotificationCallbacks(mCallbacks,
                                 mLoadGroup,
                                 NS_GET_IID(nsIProgressEventSink),
                                 getter_AddRefs(mProgressSink));

--- a/netwerk/protocol/wyciwyg/nsWyciwygChannel.cpp
+++ b/netwerk/protocol/wyciwyg/nsWyciwygChannel.cpp
@@ -183,17 +183,17 @@ nsWyciwygChannel::GetLoadGroup(nsILoadGr
   *aLoadGroup = mLoadGroup;
   NS_IF_ADDREF(*aLoadGroup);
   return NS_OK;
 }
 
 NS_IMETHODIMP
 nsWyciwygChannel::SetLoadGroup(nsILoadGroup* aLoadGroup)
 {
-  if (!CanSetLoadGroup()) {
+  if (!CanSetLoadGroup(aLoadGroup)) {
     return NS_ERROR_FAILURE;
   }
 
   mLoadGroup = aLoadGroup;
   NS_QueryNotificationCallbacks(mCallbacks,
                                 mLoadGroup,
                                 NS_GET_IID(nsIProgressEventSink),
                                 getter_AddRefs(mProgressSink));
@@ -266,17 +266,17 @@ nsWyciwygChannel::GetNotificationCallbac
   *aCallbacks = mCallbacks.get();
   NS_IF_ADDREF(*aCallbacks);
   return NS_OK;
 }
 
 NS_IMETHODIMP
 nsWyciwygChannel::SetNotificationCallbacks(nsIInterfaceRequestor* aNotificationCallbacks)
 {
-  if (!CanSetCallbacks()) {
+  if (!CanSetCallbacks(aNotificationCallbacks)) {
     return NS_ERROR_FAILURE;
   }
 
   mCallbacks = aNotificationCallbacks;
   NS_QueryNotificationCallbacks(mCallbacks,
                                 mLoadGroup,
                                 NS_GET_IID(nsIProgressEventSink),
                                 getter_AddRefs(mProgressSink));