--- a/toolkit/components/printingui/ipc/nsPrintingProxy.h
+++ b/toolkit/components/printingui/ipc/nsPrintingProxy.h
@@ -10,35 +10,35 @@
 #include "mozilla/embedding/PPrintingChild.h"
 
 namespace mozilla {
 namespace layout {
 class PRemotePrintJobChild;
 }
 }
 
-class nsPrintingProxy: public nsIPrintingPromptService,
-                       public mozilla::embedding::PPrintingChild
+class nsPrintingProxy final: public nsIPrintingPromptService,
+                             public mozilla::embedding::PPrintingChild
 {
-    virtual ~nsPrintingProxy();
-
 public:
-    nsPrintingProxy();
-
     static already_AddRefed<nsPrintingProxy> GetInstance();
 
-    nsresult Init();
-
     NS_DECL_ISUPPORTS
     NS_DECL_NSIPRINTINGPROMPTSERVICE
 
+    /**
+     * Used to proxy nsIPrintSettings.savePrintSettingsToPrefs calls to the
+     * parent process.  aFlags are nsIPrintSettings's kInitSave* flags
+     * specifying which settings to save.
+     */
     nsresult SavePrintSettings(nsIPrintSettings* aPS,
                                bool aUsePrinterNamePrefix,
                                uint32_t aFlags);
 
+protected:
     virtual PPrintProgressDialogChild*
     AllocPPrintProgressDialogChild() override;
 
     virtual bool
     DeallocPPrintProgressDialogChild(PPrintProgressDialogChild* aActor) override;
 
     virtual PPrintSettingsDialogChild*
     AllocPPrintSettingsDialogChild() override;
@@ -46,12 +46,19 @@ public:
     virtual bool
     DeallocPPrintSettingsDialogChild(PPrintSettingsDialogChild* aActor) override;
 
     virtual PRemotePrintJobChild*
     AllocPRemotePrintJobChild() override;
 
     virtual bool
     DeallocPRemotePrintJobChild(PRemotePrintJobChild* aActor) override;
+
+private:
+    nsPrintingProxy();
+
+    virtual ~nsPrintingProxy();
+
+    nsresult Init();
 };
 
 #endif