And as you said, they can also be recorded by any software you use, often unexpectedly. Your email client might be processing all the content of your emails automatically, for several purposes which might include commercial purposes, and they might be parsing and recording all URLs in the content, for example. The same is true for other (often privacy-invading) software, from a simple text editor to a whole OS. And don't forget the antivirus: it might be trying to record all the URLs it can, to scan them and block them if they are known to be malicious. And all this could be done by your browser too, of course.
When you can’t connect to a web page, you can get suggestions for alternative pages similar to the one you're trying to reach. In order to offer you suggestions, Chrome sends Google the URL of the page you're trying to reach.
In general, usage statistics do not include web page URLs or personal information, but, if you are signed in to Chrome and syncing your browsing history in your Google Account without a Sync passphrase, then Chrome usage statistics include information about the web pages you visit and your usage of them.
Crash reports contain system information at the time of the crash, and may contain web page URLs or personal information, depending on what was happening at the time the crash report was triggered.
Some versions of Chrome feature Safe Browsing technology that can identify potentially harmful sites and potentially dangerous file types not already known by Google. The full URL of the site or potentially dangerous file might also be sent to Google to help determine whether the site or file is harmful.
This of course does not mean that the URL will certainly be crawled and then included in search results. However you can never be sure of what Google (or other similar companies) is doing with your data, what they plan to do, and what they will do tomorrow. It's a company, with its software and services, with settings/goals/policies that can change very quickly any day.