I have noticed that sometimes my Chrome under Ubuntu increases zoom level. Usually, it happens when I am doing something on the keyboard so perhaps it is some touchpad or keys combinations which I am accidentally touching. I know for sure that this is not standard Ctrl+ but could not figure out what it is in order to disable it. Are there any other ZOOM keyboard shortcuts on Chrome/Linux? My current Chrome version is 54.0.2840.100.
Ctrl+Scroll changes the zoom level in Chrome. You can press Ctrl+0 to reset it to the default zoom level. You can also zoom out with Ctrl+- (Minus) and zoom in with Ctrl+= (Equals).
Now, even knowing this, I still have this happen often. It sort of seems like Ctrl is sticky in Ubuntu (or maybe I just hold it down longer than I realize :-P ).
This is likely caused by Chromium bug 253697.
To fix this, disable inertial scrolling by running the following command in a terminal window: