Windows – How to prevent Google Chrome from keeping computer awake

My computer frequently fails to sleep.

How To Reproduce The Problem

1. Open Google Chrome.
2. Play a video on YouTube.*
3. Open a new Chrome tab to some other website (such as SuperUser).
4. Close the YouTube tab (but keep the other tab open such that Google Chrome isn't completely closed).
5. Let computer sit for however many minutes are required for sleep. (But then it never sleeps!)

*(I'm 100% not sure that it needs to be YouTube, but I think the most likely scenario when I'm playing audio via Chrome is if I'm watching a YouTube video.)

I'm using Windows 10 Pro with Google Chrome Version 55.0.2883.87 m (64-bit). ("Google Chrome is up to date.")

How To Diagnose

I opened Command Prompt as an administrator and ran powercfg /requests and get this result:

[DRIVER] High Definition Audio Device (HDAUDIO\FUNC_01&VEN_10EC&DEV_0892&SUBSYS_1849D892&REV_1003\4&13fd1513&0&0001)
An audio stream is currently in use.

Through trial and error, I've narrowed down the offending program to Google Chrome. After quitting Chrome completely (all tabs) and running powercfg /requests again, the result is:

DISPLAY:
None.

SYSTEM:
None.

AWAYMODE:
None.

EXECUTION:
None.

PERFBOOST:
None.

ACTIVELOCKSCREEN:
None.

And then the PC sleeps appropriately.

What's weird is that Chrome is not actively playing an audio stream. But it has played audio recently, even though that tab is now closed and gone.

How can I ensure that my Windows 10 Pro can sleep normally even when Chrome is still open and even when a recently-closed Chrome tab played some audio?

UPDATE:

This is driving me crazy!

I've even disabled all Chrome extensions. My enabled extensions had been:

• Google Docs
• Google Docs Offline
• Google Sheets
• Google Slides
• LastPass: Free Password Manager

But I'm still having the problem. I'm not 100% sure that YouTube is relevant to the problem, but I don't know when else my Chrome uses audio.

By the way, it seems like many other people have experienced Chrome keeping their computer awake:

• https://stackoverflow.com/questions/22651873/do-html5-videos-keep-computer-on
• https://apple.stackexchange.com/questions/205228/chrome-prevents-macbook-from-sleeping
• https://stackoverflow.com/questions/40364878/certain-websites-in-chrome-keeping-computer-awake-by-activating-an-audio-stream
• https://bugs.chromium.org/p/chromium/issues/detail?id=179007
• https://techjourney.net/chrome-prevents-windows-from-going-into-sleep-standby-or-hibernation-mode/
• http://www.jasonhartman.net/2012/06/windows-7-wont-go-to-sleep-mode-audio.html

I'm shocked this hasn't gotten more attention because it's really annoying.