--- a/extensions/gio/nsGIOProtocolHandler.cpp
+++ b/extensions/gio/nsGIOProtocolHandler.cpp
@@ -130,17 +130,17 @@ static void mount_enclosing_volume_finis
 static void mount_operation_ask_password (GMountOperation   *mount_op,
                                           const char        *message,
                                           const char        *default_user,
                                           const char        *default_domain,
                                           GAskPasswordFlags flags,
                                           gpointer          user_data);
 //-----------------------------------------------------------------------------
 
-class nsGIOInputStream : public nsIInputStream
+class nsGIOInputStream MOZ_FINAL : public nsIInputStream
 {
   public:
     NS_DECL_ISUPPORTS
     NS_DECL_NSIINPUTSTREAM
 
     nsGIOInputStream(const nsCString &uriSpec)
       : mSpec(uriSpec)
       , mChannel(nullptr)
@@ -875,28 +875,28 @@ mount_operation_ask_password (GMountOper
   g_mount_operation_set_password(mount_op, NS_ConvertUTF16toUTF8(pass).get());
   nsMemory::Free(user);
   nsMemory::Free(pass);
   g_mount_operation_reply(mount_op, G_MOUNT_OPERATION_HANDLED);
 }
 
 //-----------------------------------------------------------------------------
 
-class nsGIOProtocolHandler : public nsIProtocolHandler
-                           , public nsIObserver
+class nsGIOProtocolHandler MOZ_FINAL : public nsIProtocolHandler
+                                     , public nsIObserver
 {
   public:
     NS_DECL_ISUPPORTS
     NS_DECL_NSIPROTOCOLHANDLER
     NS_DECL_NSIOBSERVER
 
     nsresult Init();
 
   private:
-    void   InitSupportedProtocolsPref(nsIPrefBranch *prefs);
+    void InitSupportedProtocolsPref(nsIPrefBranch *prefs);
     bool IsSupportedProtocol(const nsCString &spec);
 
     nsCString mSupportedProtocols;
 };
 
 NS_IMPL_ISUPPORTS2(nsGIOProtocolHandler, nsIProtocolHandler, nsIObserver)
 
 nsresult

--- a/toolkit/system/gnome/nsGSettingsService.cpp
+++ b/toolkit/system/gnome/nsGSettingsService.cpp
@@ -72,17 +72,17 @@ GSETTINGS_FUNCTIONS
 #define g_variant_is_of_type _g_variant_is_of_type
 #define g_variant_new_int32 _g_variant_new_int32
 #define g_variant_new_boolean _g_variant_new_boolean
 #define g_variant_new_string _g_variant_new_string
 #define g_variant_unref _g_variant_unref
 
 static PRLibrary *gioLib = nullptr;
 
-class nsGSettingsCollection : public nsIGSettingsCollection
+class nsGSettingsCollection MOZ_FINAL : public nsIGSettingsCollection
 {
 public:
   NS_DECL_ISUPPORTS
   NS_DECL_NSIGSETTINGSCOLLECTION
 
   nsGSettingsCollection(GSettings* aSettings) : mSettings(aSettings),
                                                 mKeys(NULL) {}
   ~nsGSettingsCollection();

--- a/toolkit/system/gnome/nsGSettingsService.h
+++ b/toolkit/system/gnome/nsGSettingsService.h
@@ -6,17 +6,17 @@
 #ifndef nsGSettingsService_h_
 #define nsGSettingsService_h_
 
 #include "nsIGSettingsService.h"
 
 #define NS_GSETTINGSSERVICE_CID \
 {0xbfd4a9d8, 0xd886, 0x4161, {0x81, 0xef, 0x88, 0x68, 0xda, 0x11, 0x41, 0x70}}
 
-class nsGSettingsService : public nsIGSettingsService
+class nsGSettingsService MOZ_FINAL : public nsIGSettingsService
 {
 public:
   NS_DECL_ISUPPORTS
   NS_DECL_NSIGSETTINGSSERVICE
 
   NS_HIDDEN_(nsresult) Init();
 
 private: