diff --git a/xpcom/components/nsGenericFactory.cpp b/xpcom/components/nsGenericFactory.cpp
index a980bb33c25..9cc0194c998 100644
--- a/xpcom/components/nsGenericFactory.cpp
+++ b/xpcom/components/nsGenericFactory.cpp
@@ -100,12 +100,14 @@ NS_NewGenericFactory(nsIGenericFactory* *result,
 ////////////////////////////////////////////////////////////////////////////////
 
 nsGenericModule::nsGenericModule(const char* moduleName, PRUint32 componentCount,
-                                 nsModuleComponentInfo* components)
+                                 nsModuleComponentInfo* components,
+                                 nsModuleDestructorProc dtor)
     : mInitialized(PR_FALSE), 
       mModuleName(moduleName),
       mComponentCount(componentCount),
       mComponents(components),
-      mFactories(8, PR_FALSE)
+      mFactories(8, PR_FALSE),
+      mDtor(dtor)
 {
     NS_INIT_ISUPPORTS();
 }
@@ -132,6 +134,8 @@ nsGenericModule::Initialize()
 void
 nsGenericModule::Shutdown()
 {
+    if (mDtor)
+        mDtor(this);
     // Release the factory objects
     mFactories.Reset();
 }
@@ -257,6 +261,7 @@ NS_COM nsresult
 NS_NewGenericModule(const char* moduleName,
                     PRUint32 componentCount,
                     nsModuleComponentInfo* components,
+                    nsModuleDestructorProc dtor,
                     nsIModule* *result)
 {
     nsresult rv = NS_OK;
@@ -265,7 +270,7 @@ NS_NewGenericModule(const char* moduleName,
 
     // Create and initialize the module instance
     nsGenericModule *m = 
-        new nsGenericModule(moduleName, componentCount, components);
+        new nsGenericModule(moduleName, componentCount, components, dtor);
     if (!m) {
         return NS_ERROR_OUT_OF_MEMORY;
     }
diff --git a/xpcom/components/nsGenericFactory.h b/xpcom/components/nsGenericFactory.h
index 64e7df7b5fd..15567249bfd 100644
--- a/xpcom/components/nsGenericFactory.h
+++ b/xpcom/components/nsGenericFactory.h
@@ -70,7 +70,8 @@ class nsGenericModule : public nsIModule
 {
 public:
     nsGenericModule(const char* moduleName, PRUint32 componentCount,
-                    nsModuleComponentInfo* components);
+                    nsModuleComponentInfo* components,
+                    nsModuleDestructorProc dtor);
     virtual ~nsGenericModule();
 
     NS_DECL_ISUPPORTS
@@ -87,6 +88,7 @@ protected:
     PRUint32                    mComponentCount;
     nsModuleComponentInfo*      mComponents;
     nsSupportsHashtable         mFactories;
+    nsModuleDestructorProc      mDtor;
 };
 
 #endif /* nsGenericFactory_h___ */
diff --git a/xpcom/components/nsIGenericFactory.h b/xpcom/components/nsIGenericFactory.h
index 79e6bf370f2..80914d46079 100644
--- a/xpcom/components/nsIGenericFactory.h
+++ b/xpcom/components/nsIGenericFactory.h
@@ -85,20 +85,26 @@ struct nsModuleComponentInfo {
     nsIGenericFactory::ConstructorProcPtr       mConstructor;
 };
 
+typedef void (PR_CALLBACK *nsModuleDestructorProc) (nsIModule *self);
+
 extern NS_COM nsresult
 NS_NewGenericModule(const char* moduleName,
                     PRUint32 componentCount,
                     nsModuleComponentInfo* components,
+                    nsModuleDestructorProc dtor,
                     nsIModule* *result);
 
 #define NS_IMPL_NSGETMODULE(_name, _components)                              \
+    NS_IMPL_NSGETMODULE_WITH_DTOR(_name, _components, nsnull)
+
+#define NS_IMPL_NSGETMODULE_WITH_DTOR(_name, _components, _dtor)             \
 extern "C" NS_EXPORT nsresult NSGetModule(nsIComponentManager *servMgr,      \
                                           nsIFileSpec* location,             \
                                           nsIModule** result)                \
 {                                                                            \
     return NS_NewGenericModule((_name),                                      \
                                sizeof(_components) / sizeof(_components[0]), \
-                               (_components), result);                       \
+                               (_components), _dtor, result);                \
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -167,4 +173,36 @@ _InstanceClass##Constructor(nsISupports *aOuter, REFNSIID aIID, void **aResult)
     return rv;                                                                  \
 }                                                                               \
 
+// 'Constructor' that uses an existing getter function that gets a singleton.
+// NOTE: assumes that getter does an AddRef - so additional AddRef is not done.
+#define NS_GENERIC_FACTORY_SINGLETON_CONSTRUCTOR(_InstanceClass, _GetterProc)   \
+static NS_IMETHODIMP                                                            \
+_InstanceClass##Constructor(nsISupports *aOuter, REFNSIID aIID, void **aResult) \
+{                                                                               \
+    nsresult rv;                                                                \
+                                                                                \
+    _InstanceClass * inst;                                                      \
+                                                                                \
+    if (NULL == aResult) {                                                      \
+        rv = NS_ERROR_NULL_POINTER;                                             \
+        return rv;                                                              \
+    }                                                                           \
+    *aResult = NULL;                                                            \
+    if (NULL != aOuter) {                                                       \
+        rv = NS_ERROR_NO_AGGREGATION;                                           \
+        return rv;                                                              \
+    }                                                                           \
+                                                                                \
+    inst = _GetterProc();                                                       \
+    if (NULL == inst) {                                                         \
+        rv = NS_ERROR_OUT_OF_MEMORY;                                            \
+        return rv;                                                              \
+    }                                                                           \
+    /* NS_ADDREF(inst); */                                                      \
+    rv = inst->QueryInterface(aIID, aResult);                                   \
+    NS_RELEASE(inst);                                                           \
+                                                                                \
+    return rv;                                                                  \
+}                                                                               \
+
 #endif /* nsIGenericFactory_h___ */
diff --git a/xpcom/glue/nsGenericFactory.cpp b/xpcom/glue/nsGenericFactory.cpp
index a980bb33c25..9cc0194c998 100644
--- a/xpcom/glue/nsGenericFactory.cpp
+++ b/xpcom/glue/nsGenericFactory.cpp
@@ -100,12 +100,14 @@ NS_NewGenericFactory(nsIGenericFactory* *result,
 ////////////////////////////////////////////////////////////////////////////////
 
 nsGenericModule::nsGenericModule(const char* moduleName, PRUint32 componentCount,
-                                 nsModuleComponentInfo* components)
+                                 nsModuleComponentInfo* components,
+                                 nsModuleDestructorProc dtor)
     : mInitialized(PR_FALSE), 
       mModuleName(moduleName),
       mComponentCount(componentCount),
       mComponents(components),
-      mFactories(8, PR_FALSE)
+      mFactories(8, PR_FALSE),
+      mDtor(dtor)
 {
     NS_INIT_ISUPPORTS();
 }
@@ -132,6 +134,8 @@ nsGenericModule::Initialize()
 void
 nsGenericModule::Shutdown()
 {
+    if (mDtor)
+        mDtor(this);
     // Release the factory objects
     mFactories.Reset();
 }
@@ -257,6 +261,7 @@ NS_COM nsresult
 NS_NewGenericModule(const char* moduleName,
                     PRUint32 componentCount,
                     nsModuleComponentInfo* components,
+                    nsModuleDestructorProc dtor,
                     nsIModule* *result)
 {
     nsresult rv = NS_OK;
@@ -265,7 +270,7 @@ NS_NewGenericModule(const char* moduleName,
 
     // Create and initialize the module instance
     nsGenericModule *m = 
-        new nsGenericModule(moduleName, componentCount, components);
+        new nsGenericModule(moduleName, componentCount, components, dtor);
     if (!m) {
         return NS_ERROR_OUT_OF_MEMORY;
     }
diff --git a/xpcom/glue/nsGenericFactory.h b/xpcom/glue/nsGenericFactory.h
index 64e7df7b5fd..15567249bfd 100644
--- a/xpcom/glue/nsGenericFactory.h
+++ b/xpcom/glue/nsGenericFactory.h
@@ -70,7 +70,8 @@ class nsGenericModule : public nsIModule
 {
 public:
     nsGenericModule(const char* moduleName, PRUint32 componentCount,
-                    nsModuleComponentInfo* components);
+                    nsModuleComponentInfo* components,
+                    nsModuleDestructorProc dtor);
     virtual ~nsGenericModule();
 
     NS_DECL_ISUPPORTS
@@ -87,6 +88,7 @@ protected:
     PRUint32                    mComponentCount;
     nsModuleComponentInfo*      mComponents;
     nsSupportsHashtable         mFactories;
+    nsModuleDestructorProc      mDtor;
 };
 
 #endif /* nsGenericFactory_h___ */
diff --git a/xpcom/glue/nsIGenericFactory.h b/xpcom/glue/nsIGenericFactory.h
index 79e6bf370f2..80914d46079 100644
--- a/xpcom/glue/nsIGenericFactory.h
+++ b/xpcom/glue/nsIGenericFactory.h
@@ -85,20 +85,26 @@ struct nsModuleComponentInfo {
     nsIGenericFactory::ConstructorProcPtr       mConstructor;
 };
 
+typedef void (PR_CALLBACK *nsModuleDestructorProc) (nsIModule *self);
+
 extern NS_COM nsresult
 NS_NewGenericModule(const char* moduleName,
                     PRUint32 componentCount,
                     nsModuleComponentInfo* components,
+                    nsModuleDestructorProc dtor,
                     nsIModule* *result);
 
 #define NS_IMPL_NSGETMODULE(_name, _components)                              \
+    NS_IMPL_NSGETMODULE_WITH_DTOR(_name, _components, nsnull)
+
+#define NS_IMPL_NSGETMODULE_WITH_DTOR(_name, _components, _dtor)             \
 extern "C" NS_EXPORT nsresult NSGetModule(nsIComponentManager *servMgr,      \
                                           nsIFileSpec* location,             \
                                           nsIModule** result)                \
 {                                                                            \
     return NS_NewGenericModule((_name),                                      \
                                sizeof(_components) / sizeof(_components[0]), \
-                               (_components), result);                       \
+                               (_components), _dtor, result);                \
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -167,4 +173,36 @@ _InstanceClass##Constructor(nsISupports *aOuter, REFNSIID aIID, void **aResult)
     return rv;                                                                  \
 }                                                                               \
 
+// 'Constructor' that uses an existing getter function that gets a singleton.
+// NOTE: assumes that getter does an AddRef - so additional AddRef is not done.
+#define NS_GENERIC_FACTORY_SINGLETON_CONSTRUCTOR(_InstanceClass, _GetterProc)   \
+static NS_IMETHODIMP                                                            \
+_InstanceClass##Constructor(nsISupports *aOuter, REFNSIID aIID, void **aResult) \
+{                                                                               \
+    nsresult rv;                                                                \
+                                                                                \
+    _InstanceClass * inst;                                                      \
+                                                                                \
+    if (NULL == aResult) {                                                      \
+        rv = NS_ERROR_NULL_POINTER;                                             \
+        return rv;                                                              \
+    }                                                                           \
+    *aResult = NULL;                                                            \
+    if (NULL != aOuter) {                                                       \
+        rv = NS_ERROR_NO_AGGREGATION;                                           \
+        return rv;                                                              \
+    }                                                                           \
+                                                                                \
+    inst = _GetterProc();                                                       \
+    if (NULL == inst) {                                                         \
+        rv = NS_ERROR_OUT_OF_MEMORY;                                            \
+        return rv;                                                              \
+    }                                                                           \
+    /* NS_ADDREF(inst); */                                                      \
+    rv = inst->QueryInterface(aIID, aResult);                                   \
+    NS_RELEASE(inst);                                                           \
+                                                                                \
+    return rv;                                                                  \
+}                                                                               \
+
 #endif /* nsIGenericFactory_h___ */