diff -r 000000000000 -r 6474c204b198 xpcom/glue/nsCycleCollectionTraversalCallback.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/glue/nsCycleCollectionTraversalCallback.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,58 @@
+/* -*- 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/. */
+
+#ifndef nsCycleCollectionTraversalCallback_h__
+#define nsCycleCollectionTraversalCallback_h__
+
+#include "nsISupports.h"
+
+class nsCycleCollectionParticipant;
+
+class NS_NO_VTABLE nsCycleCollectionTraversalCallback
+{
+public:
+  // You must call DescribeRefCountedNode() with an accurate
+  // refcount, otherwise cycle collection will fail, and probably crash.
+  // If the callback cares about objname, it should put
+  // WANT_DEBUG_INFO in mFlags.
+  NS_IMETHOD_(void) DescribeRefCountedNode(nsrefcnt refcount,
+                                           const char* objname) = 0;
+  // Note, aCompartmentAddress is 0 if it is unknown.
+  NS_IMETHOD_(void) DescribeGCedNode(bool ismarked,
+                                     const char* objname,
+                                     uint64_t aCompartmentAddress = 0) = 0;
+
+  NS_IMETHOD_(void) NoteXPCOMChild(nsISupports *child) = 0;
+  NS_IMETHOD_(void) NoteJSChild(void *child) = 0;
+  NS_IMETHOD_(void) NoteNativeChild(void *child,
+                                    nsCycleCollectionParticipant *helper) = 0;
+
+  // Give a name to the edge associated with the next call to
+  // NoteXPCOMChild, NoteJSChild, or NoteNativeChild.
+  // Callbacks who care about this should set WANT_DEBUG_INFO in the
+  // flags.
+  NS_IMETHOD_(void) NoteNextEdgeName(const char* name) = 0;
+
+  enum {
+    // Values for flags:
+
+    // Caller should call NoteNextEdgeName and pass useful objName
+    // to DescribeRefCountedNode and DescribeGCedNode.
+    WANT_DEBUG_INFO = (1<<0),
+
+    // Caller should not skip objects that we know will be
+    // uncollectable.
+    WANT_ALL_TRACES = (1<<1)
+  };
+  uint32_t Flags() const { return mFlags; }
+  bool WantDebugInfo() const { return (mFlags & WANT_DEBUG_INFO) != 0; }
+  bool WantAllTraces() const { return (mFlags & WANT_ALL_TRACES) != 0; }
+protected:
+  nsCycleCollectionTraversalCallback() : mFlags(0) {}
+
+  uint32_t mFlags;
+};
+
+#endif // nsCycleCollectionTraversalCallback_h__