diff -r 000000000000 -r 6474c204b198 tools/profiler/ProfilerIOInterposeObserver.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tools/profiler/ProfilerIOInterposeObserver.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,28 @@
+/* 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 PROFILERIOINTERPOSEOBSERVER_H
+#define PROFILERIOINTERPOSEOBSERVER_H
+
+#ifdef MOZ_ENABLE_PROFILER_SPS
+
+#include "mozilla/IOInterposer.h"
+
+namespace mozilla {
+
+/**
+ * This class is the observer that calls into the profiler whenever
+ * main thread I/O occurs.
+ */
+class ProfilerIOInterposeObserver MOZ_FINAL : public IOInterposeObserver
+{
+public:
+  virtual void Observe(Observation& aObservation);
+};
+
+} // namespace mozilla
+
+#endif // MOZ_ENABLE_PROFILER_SPS
+
+#endif // PROFILERIOINTERPOSEOBSERVER_H