Add tracing AutoOpenCloseEvent.

base/trace_event/vfc_persistent_async_event.h

Index: base/trace_event/vfc_persistent_async_event.h
diff --git a/base/trace_event/vfc_persistent_async_event.h b/base/trace_event/vfc_persistent_async_event.h
new file mode 100644
index 0000000000000000000000000000000000000000..566cf94977adf1ab5ed40a7c28ef5fe37de6e061
--- /dev/null
+++ b/base/trace_event/vfc_persistent_async_event.h
@@ -0,0 +1,31 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_TRACE_EVENT_VFC_PERSISTENT_ASYNC_H_
+#define BASE_TRACE_EVENT_VFC_PERSISTENT_ASYNC_H_
+
+#include "base/macros.h"
+#include "base/trace_event/persistent_async_event.h"
+#include "base/trace_event/trace_event.h"
+#include <string>
+#include <ctime>
+
+namespace base {
+namespace trace_event {
+
+class BASE_EXPORT VFCPersistentAsyncEvent
+		: public PersistentAsyncEvent {
+	public:
+	VFCPersistentAsyncEvent();
+	~VFCPersistentAsyncEvent() override;
+
+	void RecordStartEvent() override;
+	void RecordStartEventWithOffset(double offset) override;
+	void RecordStopEvent() override;
+};
+
+}
+}
+
+#endif // BASE_TRACE_EVENT_PERSISTENT_ASYNC_H_