diff --git a/mozilla/webshell/tests/viewer/nsWebBrowserChrome.cpp b/mozilla/webshell/tests/viewer/nsWebBrowserChrome.cpp
index c47aa057a1e..d57957611cd 100644
--- a/mozilla/webshell/tests/viewer/nsWebBrowserChrome.cpp
+++ b/mozilla/webshell/tests/viewer/nsWebBrowserChrome.cpp
@@ -68,6 +68,7 @@ NS_INTERFACE_MAP_BEGIN(nsWebBrowserChrome)
    NS_INTERFACE_MAP_ENTRY(nsIWebBrowserChrome)
    NS_INTERFACE_MAP_ENTRY(nsIWebProgressListener)
    NS_INTERFACE_MAP_ENTRY(nsIBaseWindow)
+   NS_INTERFACE_MAP_ENTRY(nsISupportsWeakReference)
 NS_INTERFACE_MAP_END
 
 //*****************************************************************************
diff --git a/mozilla/webshell/tests/viewer/nsWebBrowserChrome.h b/mozilla/webshell/tests/viewer/nsWebBrowserChrome.h
index 3a3f80d58b0..d27f05ef7ca 100644
--- a/mozilla/webshell/tests/viewer/nsWebBrowserChrome.h
+++ b/mozilla/webshell/tests/viewer/nsWebBrowserChrome.h
@@ -33,13 +33,15 @@
 #include "nsIInterfaceRequestor.h"
 #include "nsIWebProgressListener.h"
 #include "nsTimer.h"
+#include "nsWeakReference.h"
 
 class nsBrowserWindow;
 
 class nsWebBrowserChrome : public nsIWebBrowserChrome,
                            public nsIBaseWindow,
                            public nsIWebProgressListener,
-                           public nsIInterfaceRequestor
+                           public nsIInterfaceRequestor,
+                           public nsSupportsWeakReference
 {
 friend class nsBrowserWindow;