For a long time, I have always wondered why my download managers always pops up dialog boxes to download files when I visit certain pages in chrome. I have always attributed it to false positives or buggy software. I stumbled upon the answer just a few days ago.
Apparently, google decided it was nice to preload pages in advance. In other words, when you visit certain pages, chrome predicts which link you click and load the page even if you did not click on the link. The behaviour is turned on by default. Why is this bad? Firstly, if you have quota on your usage, you dont want to be downloading unnecessary files. Some preloaded files include pdfs which can be quite large. More importantly, downloading the file means storing it on your hard disk. If the file contains questionable content, you would be hard pressed to explain to authorities how the file got onto your hard disk.
To turn it off, click advanced settings on the settings panel and uncheck "Predict network actions to improve page load performance"