I (accidentally) started downloading a 350 MB file from Google Chrome and I can't find the option to stop it, the downloads app just shows the files that have already finished but not the downloads in progress. The notification on my top bar just opens the downloads app.
I just reproduced the steps needed to do this, last two steps may be the interesting ones:
- Open Google Chrome (v39)
- Start a large download (http://ipv4.download.thinkbroadband.com/1GB.zip)
- Wait a moment (it took some seconds for a notification to appear)
- Pull down the notification bar and click on the download entry
- You are taken to the download manager
- Long click on the corresponding entry
- Choose the trash bin from the top action bar
In case this does not work for you: Please edit your answer with your exact device model, Chrome and Android version number. If you are doing a lot of downloads on your Android device consider installing a download manager like share downloader. It also supports pause and resume.