diff -r 000000000000 -r 6474c204b198 xpcom/base/AvailableMemoryTracker.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/base/AvailableMemoryTracker.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,30 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 ci et: */
+/* 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 mozilla_AvailableMemoryTracker_h
+#define mozilla_AvailableMemoryTracker_h
+
+namespace mozilla {
+namespace AvailableMemoryTracker {
+
+// The AvailableMemoryTracker launches a memory pressure watcher on all
+// platforms to react to low-memory situations and on Windows it implements
+// the full functionality used to monitor how much memory is available.
+//
+// Init() must be called before any other threads have started, because it
+// modifies the in-memory implementations of some DLL functions in
+// non-thread-safe ways.
+//
+// The hooks don't do anything until Activate() is called.  It's an error to
+// call Activate() without first calling Init().
+
+void Init();
+void Activate();
+
+} // namespace AvailableMemoryTracker
+} // namespace mozilla
+
+#endif // ifndef mozilla_AvailableMemoryTracker_h