diff -r 000000000000 -r 6474c204b198 xpcom/ds/nsObserverList.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/ds/nsObserverList.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,92 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+#ifndef nsObserverList_h___
+#define nsObserverList_h___
+
+#include "nsISupports.h"
+#include "nsTArray.h"
+#include "nsCOMPtr.h"
+#include "nsCOMArray.h"
+#include "nsIObserver.h"
+#include "nsIWeakReference.h"
+#include "nsHashKeys.h"
+#include "nsISimpleEnumerator.h"
+#include "mozilla/Attributes.h"
+
+namespace mozilla {
+class ObserverServiceReporter;
+} // namespace mozilla
+
+struct ObserverRef
+{
+  ObserverRef(const ObserverRef& o) :
+    isWeakRef(o.isWeakRef), ref(o.ref) { }
+  
+  ObserverRef(nsIObserver* aObserver) : isWeakRef(false), ref(aObserver) { }
+  ObserverRef(nsIWeakReference* aWeak) : isWeakRef(true), ref(aWeak) { }
+
+  bool isWeakRef;
+  nsCOMPtr<nsISupports> ref;
+
+  nsIObserver* asObserver() {
+    NS_ASSERTION(!isWeakRef, "Isn't a strong ref.");
+    return static_cast<nsIObserver*>((nsISupports*) ref);
+  }
+
+  nsIWeakReference* asWeak() {
+    NS_ASSERTION(isWeakRef, "Isn't a weak ref.");
+    return static_cast<nsIWeakReference*>((nsISupports*) ref);
+  }
+
+  bool operator==(nsISupports* b) const { return ref == b; }
+};
+
+class nsObserverList : public nsCharPtrHashKey
+{
+  friend class nsObserverService;
+
+public:
+  nsObserverList(const char *key) : nsCharPtrHashKey(key)
+  { MOZ_COUNT_CTOR(nsObserverList); }
+
+  ~nsObserverList() { MOZ_COUNT_DTOR(nsObserverList); }
+
+  nsresult AddObserver(nsIObserver* anObserver, bool ownsWeak);
+  nsresult RemoveObserver(nsIObserver* anObserver);
+
+  void NotifyObservers(nsISupports *aSubject,
+                       const char *aTopic,
+                       const char16_t *someData);
+  nsresult GetObserverList(nsISimpleEnumerator** anEnumerator);
+
+  // Fill an array with the observers of this category.
+  // The array is filled in last-added-first order.
+  void FillObserverArray(nsCOMArray<nsIObserver> &aArray);
+
+  // Unmark any strongly held observers implemented in JS so the cycle
+  // collector will not traverse them.
+  void UnmarkGrayStrongObservers();
+
+private:
+  nsTArray<ObserverRef> mObservers;
+};
+
+class nsObserverEnumerator MOZ_FINAL : public nsISimpleEnumerator
+{
+public:
+    NS_DECL_ISUPPORTS
+    NS_DECL_NSISIMPLEENUMERATOR
+
+    nsObserverEnumerator(nsObserverList* aObserverList);
+
+private:
+    ~nsObserverEnumerator() { }
+
+    int32_t mIndex; // Counts up from 0
+    nsCOMArray<nsIObserver> mObservers;
+};
+
+#endif /* nsObserverList_h___ */