diff -r 000000000000 -r 6474c204b198 xpcom/ds/nsObserverList.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/ds/nsObserverList.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,136 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsObserverList.h"
+
+#include "nsAutoPtr.h"
+#include "nsCOMArray.h"
+#include "nsISimpleEnumerator.h"
+#include "xpcpublic.h"
+
+nsresult
+nsObserverList::AddObserver(nsIObserver* anObserver, bool ownsWeak)
+{
+    NS_ASSERTION(anObserver, "Null input");
+
+    if (!ownsWeak) {
+        ObserverRef* o = mObservers.AppendElement(anObserver);
+        if (!o)
+            return NS_ERROR_OUT_OF_MEMORY;
+
+        return NS_OK;
+    }
+        
+    nsCOMPtr<nsIWeakReference> weak = do_GetWeakReference(anObserver);
+    if (!weak)
+        return NS_NOINTERFACE;
+
+    ObserverRef *o = mObservers.AppendElement(weak);
+    if (!o)
+        return NS_ERROR_OUT_OF_MEMORY;
+
+    return NS_OK;
+}
+
+nsresult
+nsObserverList::RemoveObserver(nsIObserver* anObserver)
+{
+    NS_ASSERTION(anObserver, "Null input");
+
+    if (mObservers.RemoveElement(static_cast<nsISupports*>(anObserver)))
+        return NS_OK;
+
+    nsCOMPtr<nsIWeakReference> observerRef = do_GetWeakReference(anObserver);
+    if (!observerRef)
+        return NS_ERROR_FAILURE;
+
+    if (!mObservers.RemoveElement(observerRef))
+        return NS_ERROR_FAILURE;
+
+    return NS_OK;
+}
+
+nsresult
+nsObserverList::GetObserverList(nsISimpleEnumerator** anEnumerator)
+{
+    nsRefPtr<nsObserverEnumerator> e(new nsObserverEnumerator(this));
+    e.forget(anEnumerator);
+    return NS_OK;
+}
+
+void
+nsObserverList::FillObserverArray(nsCOMArray<nsIObserver> &aArray)
+{
+    aArray.SetCapacity(mObservers.Length());
+
+    nsTArray<ObserverRef> observers(mObservers);
+
+    for (int32_t i = observers.Length() - 1; i >= 0; --i) {
+        if (observers[i].isWeakRef) {
+            nsCOMPtr<nsIObserver> o(do_QueryReferent(observers[i].asWeak()));
+            if (o) {
+                aArray.AppendObject(o);
+            }
+            else {
+                // the object has gone away, remove the weakref
+                mObservers.RemoveElement(observers[i].asWeak());
+            }
+        }
+        else {
+            aArray.AppendObject(observers[i].asObserver());
+        }
+    }
+}
+
+void
+nsObserverList::NotifyObservers(nsISupports *aSubject,
+                                const char *aTopic,
+                                const char16_t *someData)
+{
+    nsCOMArray<nsIObserver> observers;
+    FillObserverArray(observers);
+
+    for (int32_t i = 0; i < observers.Count(); ++i) {
+        observers[i]->Observe(aSubject, aTopic, someData);
+    }
+}
+
+void
+nsObserverList::UnmarkGrayStrongObservers()
+{
+    for (uint32_t i = 0; i < mObservers.Length(); ++i) {
+        if (!mObservers[i].isWeakRef) {
+            xpc_TryUnmarkWrappedGrayObject(mObservers[i].asObserver());
+        }
+    }
+}
+
+NS_IMPL_ISUPPORTS(nsObserverEnumerator, nsISimpleEnumerator)
+
+nsObserverEnumerator::nsObserverEnumerator(nsObserverList* aObserverList)
+    : mIndex(0)
+{
+    aObserverList->FillObserverArray(mObservers);
+}
+
+NS_IMETHODIMP
+nsObserverEnumerator::HasMoreElements(bool *aResult)
+{
+    *aResult = (mIndex < mObservers.Count());
+    return NS_OK;
+}
+
+NS_IMETHODIMP
+nsObserverEnumerator::GetNext(nsISupports* *aResult)
+{
+    if (mIndex == mObservers.Count()) {
+        NS_ERROR("Enumerating after HasMoreElements returned false.");
+        return NS_ERROR_UNEXPECTED;
+    }
+
+    NS_ADDREF(*aResult = mObservers[mIndex]);
+    ++mIndex;
+    return NS_OK;
+}