--- a/dom/ipc/TabParent.cpp
+++ b/dom/ipc/TabParent.cpp
@@ -979,59 +979,65 @@ bool
 TabParent::RecvSyncMessage(const nsString& aMessage,
                            const ClonedMessageData& aData,
                            const InfallibleTArray<CpowEntry>& aCpows,
                            const IPC::Principal& aPrincipal,
                            InfallibleTArray<nsString>* aJSONRetVal)
 {
   // FIXME Permission check for TabParent in Content process
   nsIPrincipal* principal = aPrincipal;
-  ContentParent* parent = Manager()->AsContentParent();
-  if (!ContentParent::IgnoreIPCPrincipal() &&
-      parent && principal && !AssertAppPrincipal(parent, principal)) {
-    return false;
+  if (Manager()->IsContentParent()) {
+    ContentParent* parent = Manager()->AsContentParent();
+    if (!ContentParent::IgnoreIPCPrincipal() &&
+        parent && principal && !AssertAppPrincipal(parent, principal)) {
+      return false;
+    }
   }
 
   StructuredCloneData cloneData = ipc::UnpackClonedMessageDataForParent(aData);
   CpowIdHolder cpows(Manager()->GetCPOWManager(), aCpows);
   return ReceiveMessage(aMessage, true, &cloneData, &cpows, aPrincipal, aJSONRetVal);
 }
 
 bool
 TabParent::AnswerRpcMessage(const nsString& aMessage,
                             const ClonedMessageData& aData,
                             const InfallibleTArray<CpowEntry>& aCpows,
                             const IPC::Principal& aPrincipal,
                             InfallibleTArray<nsString>* aJSONRetVal)
 {
   // FIXME Permission check for TabParent in Content process
   nsIPrincipal* principal = aPrincipal;
-  ContentParent* parent = Manager()->AsContentParent();
-  if (!ContentParent::IgnoreIPCPrincipal() &&
-      parent && principal && !AssertAppPrincipal(parent, principal)) {
-    return false;
+  if (Manager()->IsContentParent()) {
+    ContentParent* parent = Manager()->AsContentParent();
+    if (!ContentParent::IgnoreIPCPrincipal() &&
+        parent && principal && !AssertAppPrincipal(parent, principal)) {
+      return false;
+    }
   }
 
   StructuredCloneData cloneData = ipc::UnpackClonedMessageDataForParent(aData);
   CpowIdHolder cpows(Manager()->GetCPOWManager(), aCpows);
   return ReceiveMessage(aMessage, true, &cloneData, &cpows, aPrincipal, aJSONRetVal);
 }
 
 bool
 TabParent::RecvAsyncMessage(const nsString& aMessage,
                             const ClonedMessageData& aData,
                             const InfallibleTArray<CpowEntry>& aCpows,
                             const IPC::Principal& aPrincipal)
 {
   // FIXME Permission check for TabParent in Content process
   nsIPrincipal* principal = aPrincipal;
-  ContentParent* parent = Manager()->AsContentParent();
-  if (!ContentParent::IgnoreIPCPrincipal() &&
-      parent && principal && !AssertAppPrincipal(parent, principal)) {
-    return false;
+  if (Manager()->IsContentParent()) {
+    ContentParent* parent = Manager()->AsContentParent();
+    if (!ContentParent::IgnoreIPCPrincipal() &&
+        parent && principal && !AssertAppPrincipal(parent, principal)) {
+      return false;
+    }
   }
 
   StructuredCloneData cloneData = ipc::UnpackClonedMessageDataForParent(aData);
   CpowIdHolder cpows(Manager()->GetCPOWManager(), aCpows);
   return ReceiveMessage(aMessage, false, &cloneData, &cpows, aPrincipal, nullptr);
 }
 
 bool

--- a/dom/ipc/nsIContentParent.cpp
+++ b/dom/ipc/nsIContentParent.cpp
@@ -231,20 +231,22 @@ bool
 nsIContentParent::RecvSyncMessage(const nsString& aMsg,
                                   const ClonedMessageData& aData,
                                   const InfallibleTArray<CpowEntry>& aCpows,
                                   const IPC::Principal& aPrincipal,
                                   InfallibleTArray<nsString>* aRetvals)
 {
   // FIXME Permission check in Content process
   nsIPrincipal* principal = aPrincipal;
-  ContentParent* parent = AsContentParent();
-  if (!ContentParent::IgnoreIPCPrincipal() &&
-      parent && principal && !AssertAppPrincipal(parent, principal)) {
-    return false;
+  if (IsContentParent()) {
+    ContentParent* parent = AsContentParent();
+    if (!ContentParent::IgnoreIPCPrincipal() &&
+        parent && principal && !AssertAppPrincipal(parent, principal)) {
+      return false;
+    }
   }
 
   nsRefPtr<nsFrameMessageManager> ppm = mMessageManager;
   if (ppm) {
     StructuredCloneData cloneData = ipc::UnpackClonedMessageDataForParent(aData);
     CpowIdHolder cpows(GetCPOWManager(), aCpows);
 
     ppm->ReceiveMessage(static_cast<nsIContentFrameMessageManager*>(ppm.get()),
@@ -257,20 +259,22 @@ bool
 nsIContentParent::AnswerRpcMessage(const nsString& aMsg,
                                    const ClonedMessageData& aData,
                                    const InfallibleTArray<CpowEntry>& aCpows,
                                    const IPC::Principal& aPrincipal,
                                    InfallibleTArray<nsString>* aRetvals)
 {
   // FIXME Permission check in Content process
   nsIPrincipal* principal = aPrincipal;
-  ContentParent* parent = AsContentParent();
-  if (!ContentParent::IgnoreIPCPrincipal() &&
-      parent && principal && !AssertAppPrincipal(parent, principal)) {
-    return false;
+  if (IsContentParent()) {
+    ContentParent* parent = AsContentParent();
+    if (!ContentParent::IgnoreIPCPrincipal() &&
+        parent && principal && !AssertAppPrincipal(parent, principal)) {
+      return false;
+    }
   }
 
   nsRefPtr<nsFrameMessageManager> ppm = mMessageManager;
   if (ppm) {
     StructuredCloneData cloneData = ipc::UnpackClonedMessageDataForParent(aData);
     CpowIdHolder cpows(GetCPOWManager(), aCpows);
     ppm->ReceiveMessage(static_cast<nsIContentFrameMessageManager*>(ppm.get()),
                         aMsg, true, &cloneData, &cpows, aPrincipal, aRetvals);
@@ -281,20 +285,22 @@ nsIContentParent::AnswerRpcMessage(const
 bool
 nsIContentParent::RecvAsyncMessage(const nsString& aMsg,
                                    const ClonedMessageData& aData,
                                    const InfallibleTArray<CpowEntry>& aCpows,
                                    const IPC::Principal& aPrincipal)
 {
   // FIXME Permission check in Content process
   nsIPrincipal* principal = aPrincipal;
-  ContentParent* parent = AsContentParent();
-  if (!ContentParent::IgnoreIPCPrincipal() &&
-      parent && principal && !AssertAppPrincipal(parent, principal)) {
-    return false;
+  if (IsContentParent()) {
+    ContentParent* parent = AsContentParent();
+    if (!ContentParent::IgnoreIPCPrincipal() &&
+        parent && principal && !AssertAppPrincipal(parent, principal)) {
+      return false;
+    }
   }
 
   nsRefPtr<nsFrameMessageManager> ppm = mMessageManager;
   if (ppm) {
     StructuredCloneData cloneData = ipc::UnpackClonedMessageDataForParent(aData);
     CpowIdHolder cpows(GetCPOWManager(), aCpows);
     ppm->ReceiveMessage(static_cast<nsIContentFrameMessageManager*>(ppm.get()),
                         aMsg, false, &cloneData, &cpows, aPrincipal, nullptr);