diff -r 000000000000 -r 6474c204b198 toolkit/xre/EventTracer.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/xre/EventTracer.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,23 @@
+/* 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 XRE_EVENTTRACER_H_
+#define XRE_EVENTTRACER_H_
+
+namespace mozilla {
+
+// Create a thread that will fire events back at the
+// main thread to measure responsiveness. Return true
+// if the thread was created successfully.
+//   aLog If the tracing results should be printed to
+//        the console.
+bool InitEventTracing(bool aLog);
+
+// Signal the background thread to stop, and join it.
+// Must be called from the same thread that called InitEventTracing.
+void ShutdownEventTracing();
+
+}  // namespace mozilla
+
+#endif /* XRE_EVENTTRACER_H_ */