--- a/dom/plugins/base/nsNPAPIPluginInstance.cpp
+++ b/dom/plugins/base/nsNPAPIPluginInstance.cpp
@@ -1584,59 +1584,16 @@ nsNPAPIPluginInstance::FinalizeAsyncSurf
 void
 nsNPAPIPluginInstance::SetCurrentAsyncSurface(NPAsyncSurface *surface, NPRect *changed)
 {
   if (mOwner) {
     mOwner->SetCurrentAsyncSurface(surface, changed);
   }
 }
 
-class CarbonEventModelFailureEvent : public Runnable {
-public:
-  nsCOMPtr<nsIContent> mContent;
-
-  explicit CarbonEventModelFailureEvent(nsIContent* aContent)
-    : mContent(aContent)
-  {}
-
-  ~CarbonEventModelFailureEvent() {}
-
-  NS_IMETHOD Run();
-};
-
-NS_IMETHODIMP
-CarbonEventModelFailureEvent::Run()
-{
-  nsString type = NS_LITERAL_STRING("npapi-carbon-event-model-failure");
-  nsContentUtils::DispatchTrustedEvent(mContent->GetComposedDoc(), mContent,
-                                       type, true, true);
-  return NS_OK;
-}
-
-void
-nsNPAPIPluginInstance::CarbonNPAPIFailure()
-{
-  nsCOMPtr<nsIDOMElement> element;
-  GetDOMElement(getter_AddRefs(element));
-  if (!element) {
-    return;
-  }
-
-  nsCOMPtr<nsIContent> content(do_QueryInterface(element));
-  if (!content) {
-    return;
-  }
-
-  nsCOMPtr<nsIRunnable> e = new CarbonEventModelFailureEvent(content);
-  nsresult rv = NS_DispatchToCurrentThread(e);
-  if (NS_FAILED(rv)) {
-    NS_WARNING("Failed to dispatch CarbonEventModelFailureEvent.");
-  }
-}
-
 static bool
 GetJavaVersionFromMimetype(nsPluginTag* pluginTag, nsCString& version)
 {
   for (uint32_t i = 0; i < pluginTag->MimeTypes().Length(); ++i) {
     nsCString type = pluginTag->MimeTypes()[i];
     nsAutoCString jpi("application/x-java-applet;jpi-version=");
 
     int32_t idx = type.Find(jpi, false, 0, -1);

--- a/dom/plugins/base/nsNPAPIPluginInstance.h
+++ b/dom/plugins/base/nsNPAPIPluginInstance.h
@@ -296,20 +296,16 @@ public:
 
   void URLRedirectResponse(void* notifyData, NPBool allow);
 
   NPError InitAsyncSurface(NPSize *size, NPImageFormat format,
                            void *initData, NPAsyncSurface *surface);
   NPError FinalizeAsyncSurface(NPAsyncSurface *surface);
   void SetCurrentAsyncSurface(NPAsyncSurface *surface, NPRect *changed);
 
-  // Called when the instance fails to instantiate beceause the Carbon
-  // event model is not supported.
-  void CarbonNPAPIFailure();
-
   // Returns the contents scale factor of the screen the plugin is drawn on.
   double GetContentsScaleFactor();
 
   // Returns the css zoom factor of the document the plugin is drawn on.
   float GetCSSZoomFactor();
 
   nsresult GetRunID(uint32_t *aRunID);
 

--- a/dom/plugins/ipc/PPluginInstance.ipdl
+++ b/dom/plugins/ipc/PPluginInstance.ipdl
@@ -257,21 +257,16 @@ parent:
     returns (nsCString username, nsCString password, NPError result);
 
   intr NPN_ConvertPoint(double sourceX, bool ignoreDestX, double sourceY, bool ignoreDestY, NPCoordinateSpace sourceSpace,
                        NPCoordinateSpace destSpace)
     returns (double destX, double destY, bool result);
 
   async RedrawPlugin();
 
-  // Send notification that a plugin tried to negotiate Carbon NPAPI so that
-  // users can be notified that restarting the browser in i386 mode may allow
-  // them to use the plugin.
-  sync NegotiatedCarbon();
-
   // Notifies the parent of its NPP_New result code.
   async AsyncNPP_NewResult(NPError aResult);
 
   // Sends a native window to be adopted by the native window that would be
   // returned by NPN_GetValue_NPNVnetscapeWindow. Only used on Windows.
   async SetNetscapeWindowAsParent(NativeWindowHandle childWindow);
 
   sync GetCompositionString(uint32_t aType)

--- a/dom/plugins/ipc/PluginInstanceChild.cpp
+++ b/dom/plugins/ipc/PluginInstanceChild.cpp
@@ -259,35 +259,19 @@ PluginInstanceChild::DoNPP_New()
     NPP npp = GetNPP();
 
     NPError rv = mPluginIface->newp((char*)NullableStringGet(mMimeType), npp,
                                     mMode, argc, argn.get(), argv.get(), 0);
     if (NPERR_NO_ERROR != rv) {
         return rv;
     }
 
-    Initialize();
-
-#if defined(XP_MACOSX) && defined(__i386__)
-    // If an i386 Mac OS X plugin has selected the Carbon event model then
-    // we have to fail. We do not support putting Carbon event model plugins
-    // out of process. Note that Carbon is the default model so out of process
-    // plugins need to actively negotiate something else in order to work
-    // out of process.
-    if (EventModel() == NPEventModelCarbon) {
-      // Send notification that a plugin tried to negotiate Carbon NPAPI so that
-      // users can be notified that restarting the browser in i386 mode may allow
-      // them to use the plugin.
-      SendNegotiatedCarbon();
-
-      // Fail to instantiate.
-      rv = NPERR_MODULE_LOAD_FAILED_ERROR;
-    }
-#endif
-
+    if (!Initialize()) {
+        rv = NPERR_MODULE_LOAD_FAILED_ERROR;
+    }
     return rv;
 }
 
 int
 PluginInstanceChild::GetQuirks()
 {
     return PluginModuleChild::GetChrome()->GetQuirks();
 }
@@ -384,22 +368,24 @@ PluginInstanceChild::NPN_GetValue(NPNVar
 #if defined(MOZ_X11)
     case NPNVToolkit:
         *((NPNToolkitType*)aValue) = NPNVGtk2;
         return NPERR_NO_ERROR;
 
     case NPNVxDisplay:
         if (!mWsInfo.display) {
             // We are called before Initialize() so we have to call it now.
-           Initialize();
+           if (!Initialize()) {
+               return NPERR_GENERIC_ERROR;
+           }
            NS_ASSERTION(mWsInfo.display, "We should have a valid display!");
         }
         *(void **)aValue = mWsInfo.display;
         return NPERR_NO_ERROR;
-    
+
 #elif defined(OS_WIN)
     case NPNVToolkit:
         return NPERR_GENERIC_ERROR;
 #endif
     case NPNVprivateModeBool: {
         bool v = false;
         NPError result;
         if (!CallNPN_GetValue_NPNVprivateModeBool(&v, &result)) {
@@ -1425,17 +1411,17 @@ PluginInstanceChild::AnswerNPP_SetWindow
 bool
 PluginInstanceChild::Initialize()
 {
 #ifdef MOZ_WIDGET_GTK
     NPError rv;
 
     if (mWsInfo.display) {
         // Already initialized
-        return false;
+        return true;
     }
 
     // Request for windowless plugins is set in newp(), before this call.
     if (mWindow.type == NPWindowTypeWindow) {
         AnswerNPP_GetValue_NPPVpluginNeedsXEmbed(&mXEmbed, &rv);
 
         // Set up Xt loop for windowed plugins without XEmbed support
         if (!mXEmbed) {
@@ -1445,17 +1431,28 @@ PluginInstanceChild::Initialize()
 
     // Use default GTK display for XEmbed and windowless plugins
     if (mXEmbed || mWindow.type != NPWindowTypeWindow) {
         mWsInfo.display = DefaultXDisplay();
     }
     else {
         mWsInfo.display = xt_client_get_display();
     }
-#endif 
+#endif
+
+#if defined(XP_MACOSX) && defined(__i386__)
+    // If an i386 Mac OS X plugin has selected the Carbon event model then
+    // we have to fail. We do not support putting Carbon event model plugins
+    // out of process. Note that Carbon is the default model so out of process
+    // plugins need to actively negotiate something else in order to work
+    // out of process.
+    if (EventModel() == NPEventModelCarbon) {
+        return false;
+    }
+#endif
 
     return true;
 }
 
 mozilla::ipc::IPCResult
 PluginInstanceChild::RecvHandledWindowedPluginKeyEvent(
                        const NativeEventData& aKeyEventData,
                        const bool& aIsConsumed)

--- a/dom/plugins/ipc/PluginInstanceParent.cpp
+++ b/dom/plugins/ipc/PluginInstanceParent.cpp
@@ -2081,27 +2081,16 @@ PluginInstanceParent::RecvRedrawPlugin()
     if (!inst) {
         return IPC_FAIL_NO_REASON(this);
     }
 
     inst->RedrawPlugin();
     return IPC_OK();
 }
 
-mozilla::ipc::IPCResult
-PluginInstanceParent::RecvNegotiatedCarbon()
-{
-    nsNPAPIPluginInstance *inst = static_cast<nsNPAPIPluginInstance*>(mNPP->ndata);
-    if (!inst) {
-        return IPC_FAIL_NO_REASON(this);
-    }
-    inst->CarbonNPAPIFailure();
-    return IPC_OK();
-}
-
 nsPluginInstanceOwner*
 PluginInstanceParent::GetOwner()
 {
     nsNPAPIPluginInstance* inst = static_cast<nsNPAPIPluginInstance*>(mNPP->ndata);
     if (!inst) {
         return nullptr;
     }
     return inst->GetOwner();

--- a/dom/plugins/ipc/PluginInstanceParent.h
+++ b/dom/plugins/ipc/PluginInstanceParent.h
@@ -247,19 +247,16 @@ public:
                            double *destX,
                            double *destY,
                            bool *result) override;
 
     virtual mozilla::ipc::IPCResult
     RecvRedrawPlugin() override;
 
     virtual mozilla::ipc::IPCResult
-    RecvNegotiatedCarbon() override;
-
-    virtual mozilla::ipc::IPCResult
     RecvAsyncNPP_NewResult(const NPError& aResult) override;
 
     virtual mozilla::ipc::IPCResult
     RecvSetNetscapeWindowAsParent(const NativeWindowHandle& childWindow) override;
 
     NPError NPP_SetWindow(const NPWindow* aWindow);
 
     NPError NPP_GetValue(NPPVariable variable, void* retval);