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..b358b3bb2725a7dfde684f72f0fd91f32bc9f72b
--- /dev/null
+++ b/base/trace_event/vfc_persistent_async_event.h
@@ -0,0 +1,30 @@
+// 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_

[benjhayden, 2016/08/28 05:17:21]

Any reason not to spell out the acronym
"VideoFrameCompositorPersistentAsyncEvent" for clarity?
Alternatively, you could use the event name "VideoPlaybackPersistentAsyncEvent".

[alexandermont, 2016/08/29 18:59:07]

Done

+#define BASE_TRACE_EVENT_VFC_PERSISTENT_ASYNC_H_
+
+#include "base/macros.h"
+#include "base/time/time.h"
+#include "base/trace_event/persistent_async_event.h"
+#include "base/trace_event/trace_event.h"
+
+namespace base {
+namespace trace_event {
+
+class BASE_EXPORT VFCPersistentAsyncEvent

[benjhayden, 2016/08/28 05:17:21]

comment describing what this class is?

[alexandermont, 2016/08/29 18:59:07]

Done

+    : public PersistentAsyncEvent {
+  public:

[benjhayden, 2016/08/28 05:17:21]

1 space indent per
https://google.github.io/styleguide/cppguide.html#Class_Format

[alexandermont, 2016/08/29 18:59:07]

Done

+  VFCPersistentAsyncEvent(size_t id);
+  ~VFCPersistentAsyncEvent() override;
+
+  void RecordStartEvent() override;
+  void RecordStartEventWithTimestamp(int64_t timestamp) override;
+  void RecordStopEvent() override;
+};
+
+}
+}
+
+#endif // BASE_TRACE_EVENT_PERSISTENT_ASYNC_H_