Just reproduced this on Windows 7 as well.

Thank you for reporting this issue to us.

Unfortunately, I cannot reproduce this. I tried:
1. Open https://mrcoles.com/keys/
2. Press the right Alt key and "a" or "t"

Result:
16:46:18 >	T	keyup	84	84	0	altKey
16:46:18 >	T	keydown	84	84	0	altKey
16:46:18 >		keydown	18	18	0	altKey
16:45:59 >		keyup	18	18	0	
16:45:59 >	A	keyup	65	65	0	altKey
16:45:59 >	A	keydown	65	65	0	altKey
16:45:59 >		keydown	18	18	0	altKey

Is the Windows 7 you tried a different hardware, or you switched the OS on the same hardware? What is the language of the keyboard you're using?

Oh forgot to mention it's Polish Programmers keyboard on windows 10 and windows 7. These two systems were on two different hardwares

Thank you for providing more feedback. Adding the requester to the cc list.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

#4: thank you for the information.

I don't have Polish Programers keyboard around, passing to our test engineers and the experts.

zachary.milonas@ Thanks for the issue.

Able to reproduce this issue on Windows 10 and Ubuntu 17.10 on the latest Canary 69.0.3474.0 and Stable 67.0.3396.99 by following the below steps.
Issue is not applicable to Mac OS.

1. Launched Chrome and navigated to https://css-tricks.com/snippets/javascript/javascript-keycodes/#article-header-id-0 site.
2. Clicked on the frame and hit 'Alt Gr and any letter' and can observe that the altKey and ctrlKey values are false.

Note: - In Windows, the altKey and ctrlKey values are displayed as false if the Keyboard is set with Polish (Programmers) keyboard or United States-International Keyboard.
- In Ubuntu 17.10, if the keyboard is set to English(US) and when hitting the 'Alt Gr and any letter key', the altkey value is displayed as True and ctrlKey value is displayed as False.
- if the keyboard is set to Polish(programmer Dvorak) and when hitting the 'Alt Gr and any letter key', altKey and ctrlKey values are displayed as false.
Attached are the screen casts for reference.

Bisect Information (on windows):
================================
Good Build: 67.0.3371.0
Bad Build:  67.0.3372.0

Unable to run the per-revision bisect script, as the builds are crashing. Hence below is the manual Changelog URL from omahaproxy.

https://chromium.googlesource.com/chromium/src/+log/67.0.3371.0..67.0.3372.0?pretty=fuller&n=10000

From the above Changelog, suspecting the below change:
Reviewed-on: https://chromium-review.googlesource.com/963790

wez@ Please check and confirm if this issue is related to your change, else help us in assigning to the right owner.

Adding 'ReleaseBlock-Stable' as this is a recent break. Please feel free to remove if this is not applicable.

Thanks..

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This is working-as-intended, as per  issue 25503 ; we now report either AltGr or Ctrl+Alt, but not both sets of modifiers, so that sites which watch for e.g. Ctrl+<key> aren't confused when AltGr+<key> is pressed.

The behaviour you describe under Ubuntu - that the Alt modifier is reported when AltGr is pressed - is incorrect, so I've filed issue 857119 for us to fix Linux+ChromeOS to match the new behaviour.