I'm using Chromium 49.0.2623.108 on Ubuntu 15.10, and I have noticed for the last few days that, every day, Chromium wastes almost all my bandwidth during a long part of the day (around 10 Mbps).
I have checked the Chromium Task Manager (Shift+Esc), and it doesn't show anything. I have then run the command
sudo nethogs enp2s0 and it shows the process 31752. Upon checking the Chromium Task Manager again, I can see that process 31752 is the main Chromium process.
Then I run
sudo iftop -i enp2s0, and it shows that the IP address from where Chromium is downloading data is 188.8.131.52, which belongs to Microsoft Corporation.
But the real problem is that I have no idea of what exactly is causing this, or what is being downloaded! There are no active downloads in the browser either.