Add tracing AutoOpenCloseEvent.

base/trace_event/persistent_async_event.cc

Index: base/trace_event/persistent_async_event.cc
diff --git a/base/trace_event/persistent_async_event.cc b/base/trace_event/persistent_async_event.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5e1927d941a77768379cee57f83d07abe47d888c
--- /dev/null
+++ b/base/trace_event/persistent_async_event.cc
@@ -0,0 +1,65 @@
+// 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.
+
+#include "base/macros.h"
+#include "base/trace_event/trace_event.h"
+#include "base/trace_event/persistent_async_event.h"
+#include <string>
+#include <ctime>
+
+// test
+
+namespace base {
+namespace trace_event {
+
+PersistentAsyncEvent::PersistentAsyncEvent()
+	: active_(false) {}
+
+PersistentAsyncEvent::~PersistentAsyncEvent() {}
+
+void PersistentAsyncEvent::Start(std::string param_value) {
+	param_value_ = param_value;	
+	RecordStartEvent();
+	active_ = true;
+	gettimeofday(&start_time_, 0);

[benjhayden, 2016/08/10 18:30:00]

charliea can help you figure out what function to use to get the time.

+}
+
+void PersistentAsyncEvent::Stop(std::string param_value) {
+	param_value_ = param_value;
+	RecordStopEvent();
+	active_ = false;
+}
+
+void PersistentAsyncEvent::RecordStartEvent() {
+	TRACE_EVENT0("media", "PersistentAsyncStart");
+}
+
+void PersistentAsyncEvent::RecordStartEventWithOffset(double offset) {
+	TRACE_EVENT0("media", "PersistentAsyncStartOffset");
+}
+
+void PersistentAsyncEvent::RecordStopEvent() {
+	TRACE_EVENT0("media", "PersistentAsyncStop");
+}
+
+void PersistentAsyncEvent::OnTraceLogEnabled() {
+	if (active_)

[benjhayden, 2016/08/10 18:30:00]

braces should go on the same line

+	{
+		timeval finish_time;
+		gettimeofday(&finish_time, 0);
+		double offset = (start_time_.tv_sec - finish_time.tv_sec) + 0.000001*(start_time_.tv_usec - finish_time.tv_usec);
+		RecordStartEventWithOffset(offset);
+	}
+}
+
+void PersistentAsyncEvent::OnTraceLogDisabled() {
+	// TODO: how to get this to go off before the trace log gets disabled
+	if (active_)
+	{
+		RecordStopEvent();
+	}
+}
+
+}

[benjhayden, 2016/08/10 18:30:00]

}  // namespace trace_event

+}