UserAgent: Mozilla/5.0 (X11; CrOS x86_64 9000.91.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.110 Safari/537.36
Platform: 9000.91.0 (Official Build) stable-channel reks

Steps to reproduce the problem:
1. Not sure how to reproduce, it happens randomly while watching YouTube.
2. Having more tabs (loaded or unloaded, doesn't seem to matter) makes it happen faster.
3. 

What is the expected behavior?
For it not to crash (not sure what else to put here).

What went wrong?
Sometimes whilst I am watching YouTube videos, the entire screen will go black, and the audio will cut out. The screen usually freezes for about 1-2 seconds, then the screen will go entirely black. 3-4 seconds later, the audio will cut out. 80% of the the system will return to normal and fix itself (Although all open tabs will reload), but the other 20% of the time, the Chromebook does not return to normal and stays at a black screen with no audio, and the only way to fix it is to power off and turn it back on. Also, about 2-3 times the system has kept playing audio, but the screen was still black. I presume that the keyboard became dysfunctional as well, because keyboard shortcuts such as 'ctrl + w' did not work to close the open tabs, and even holding the power button for 10 seconds did not shut off the Chromebook, although I held the button for about 30 seconds to make sure that it wasn't just that the system had some delay to it (or something of the matter), and it took about 2 minutes before it stopped playing audio, and I was able to start up the Chromebook again.

Crashed report ID: 

How much crashed? Whole browser

Is it a problem with a plugin? No 

Did this work before? N/A 

Chrome version: 56.0.2924.110  Channel: stable
OS Version: 9000.91.0
Flash Version: Shockwave Flash 24.0 r0

This happened today, although in 'chrome://crashes' there is no reported crash. (Yes, crash reporting has been enabled for some time now, the last crash report was 4 days ago.) This usually only happens on YouTube, although it can happen on any site. Not sure how to reproduce the problem, but it does happen when all extensions are off. This is a school chromebook, so incognito is disabled, but it has happened when I try to reproduce the crash (watching YouTube videos, it usually happens faster if there are more tabs open so I try to do that to replicate it) and I have all of my extensions disabled. I presume it's a CPU or Memory error occurring, but as there is usually no crash report when this happens (even when the system restarts) it is hard to tell exactly what the happened to the system.