You can hardly see source in Chrome without the dev tools. The Ctrl+U "functionality" just generates huge HTML document (a table filled with spans to highlight syntax) and it is very slow on large websites (both generating it and rendering I'd assume).
Source HTML even, so whatever javascript changed is not there.
But for fun and laughs I saved js-generated source of a pretty big web page, opened it, and then pressed CTRL-U. It took 50 seconds to generate and render the source view. No wonder...
> document.getElementsByTagName('*').length
< 956632
(should be fun to go deeper and save this html, and then go ctrl+u on that)
edit: Tried it and it's been choking on the next "level" for the past 9 minutes. The tab is at over 1.5GB memory, I'm going to kill it.
Usually, a new tab opens whose address is "view-source:$URL_OF_PREV_PAGE". Obviously, it's not terribly hard to replicate by hand, but that's weird. As has been said since the days of old, "it worked on my machine".