UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.90 Safari/537.36

Steps to reproduce the problem:
1. Enter chrome://tracing
2. Start Youtube video
3. Start tracing using "rail" trace stage
4. Stop tracing

What is the expected behavior?
"VideoPlayback" async event should appear over the entire trace.

What went wrong?
No VideoPlayback event appears in trace.

Did this work before? Yes 

Chrome version: 54.0.2840.90  Channel: n/a
OS Version: 
Flash Version: Shockwave Flash 23.0 r0