--- a/widget/cocoa/TextInputHandler.mm
+++ b/widget/cocoa/TextInputHandler.mm
@@ -2512,17 +2512,17 @@ IMEInputHandler::GetCurrentTSMDocumentID
  *    run after the stack is finished, e.g, some methods cannot run the jobs
  *    during processing the focus event.  And also some other jobs should be
  *    run at the next focus event is processed.
  *    The pending methods are recorded in mPendingMethods.  They are executed
  *    by ExecutePendingMethods via FlushPendingMethods.
  *
  ******************************************************************************/
 
-NS_IMETHODIMP
+nsresult
 IMEInputHandler::NotifyIME(TextEventDispatcher* aTextEventDispatcher,
                            const IMENotification& aNotification)
 {
   switch (aNotification.mMessage) {
     case REQUEST_TO_COMMIT_COMPOSITION:
       CommitIMEComposition();
       return NS_OK;
     case REQUEST_TO_CANCEL_COMPOSITION:

--- a/widget/nsBaseWidget.cpp
+++ b/widget/nsBaseWidget.cpp
@@ -1753,17 +1753,17 @@ nsBaseWidget::NotifyUIStateChanged(UISta
   if (nsIDocument* doc = GetDocument()) {
     nsPIDOMWindowOuter* win = doc->GetWindow();
     if (win) {
       win->SetKeyboardIndicators(aShowAccelerators, aShowFocusRings);
     }
   }
 }
 
-NS_IMETHODIMP
+nsresult
 nsBaseWidget::NotifyIME(const IMENotification& aIMENotification)
 {
   switch (aIMENotification.mMessage) {
     case REQUEST_TO_COMMIT_COMPOSITION:
     case REQUEST_TO_CANCEL_COMPOSITION:
       // Currently, if native IME handler doesn't use TextEventDispatcher,
       // the request may be notified to mTextEventDispatcher or native IME
       // directly.  Therefore, if mTextEventDispatcher has a composition,

--- a/widget/nsBaseWidget.h
+++ b/widget/nsBaseWidget.h
@@ -258,17 +258,18 @@ public:
                                           int32_t aHorizontal,
                                           int32_t aVertical) override
                           { return NS_ERROR_NOT_IMPLEMENTED; }
   virtual MOZ_MUST_USE nsresult
                           BeginMoveDrag(mozilla::WidgetMouseEvent* aEvent) override
                           { return NS_ERROR_NOT_IMPLEMENTED; }
   virtual nsresult        ActivateNativeMenuItemAt(const nsAString& indexString) override { return NS_ERROR_NOT_IMPLEMENTED; }
   virtual nsresult        ForceUpdateNativeMenuAt(const nsAString& indexString) override { return NS_ERROR_NOT_IMPLEMENTED; }
-  NS_IMETHOD              NotifyIME(const IMENotification& aIMENotification) override final;
+  virtual nsresult        NotifyIME(const IMENotification& aIMENotification)
+                            override final;
   virtual MOZ_MUST_USE nsresult
                           StartPluginIME(const mozilla::WidgetKeyboardEvent& aKeyboardEvent,
                                          int32_t aPanelX, int32_t aPanelY,
                                          nsString& aCommitted) override
                           { return NS_ERROR_NOT_IMPLEMENTED; }
   virtual void            SetPluginFocused(bool& aFocused) override {}
   virtual void            SetCandidateWindowForPlugin(
                             const mozilla::widget::CandidateWindowPosition&

--- a/widget/nsIWidget.h
+++ b/widget/nsIWidget.h
@@ -1733,17 +1733,17 @@ public:
     }
 
     /**
      * Notify IME of the specified notification.
      *
      * @return If the notification is mouse button event and it's consumed by
      *         IME, this returns NS_SUCCESS_EVENT_CONSUMED.
      */
-    NS_IMETHOD NotifyIME(const IMENotification& aIMENotification) = 0;
+    virtual nsresult NotifyIME(const IMENotification& aIMENotification) = 0;
 
     /**
      * Start plugin IME.  If this results in a string getting committed, the
      * result is in aCommitted (otherwise aCommitted is empty).
      *
      * aKeyboardEvent     The event with which plugin IME is to be started
      * panelX and panelY  Location in screen coordinates of the IME input panel
      *                    (should be just under the plugin)

--- a/widget/uikit/nsWindow.h
+++ b/widget/uikit/nsWindow.h
@@ -79,17 +79,18 @@ public:
     NS_IMETHOD DispatchEvent(mozilla::WidgetGUIEvent* aEvent,
                              nsEventStatus& aStatus) override;
 
     void WillPaintWindow();
     bool PaintWindow(LayoutDeviceIntRegion aRegion);
 
     bool HasModalDescendents() { return false; }
 
-    //NS_IMETHOD NotifyIME(const IMENotification& aIMENotification) override;
+    //virtual nsresult
+    //NotifyIME(const IMENotification& aIMENotification) override;
     NS_IMETHOD_(void) SetInputContext(
                         const InputContext& aContext,
                         const InputContextAction& aAction);
     NS_IMETHOD_(InputContext) GetInputContext();
     /*
     NS_IMETHOD_(bool) ExecuteNativeKeyBinding(
                         NativeKeyBindingsType aType,
                         const mozilla::WidgetKeyboardEvent& aEvent,