Version 55.0.2883.42 beta (64-bit)
Platform 8872.44.0 (Official Build) beta-channel samus

What steps will reproduce the problem?
(1) Navigate to https://pixlr.com/editor/

What is the expected result?
One should be offered to use Flash

What happens instead?
One sees an error message with a link to get Flash player.

Chrome probably fails to detect that Flash is needed if the detection is done by the site in a way that doesn't use Flash. However, there is a download URL, https://get.adobe.com/flashplayer which could be used to trigger the "This site wants to use Flash" and allow it to be enabled. The user could still decide to go get the latest Flash version.

On Chromebooks this basically prevents using the site altogether. I didn't check on other platforms.