More likely it is not malware. Someone with a similar problem offered how he fixed it in Windows 10. If you have Windows 10 I suggest you seek
advice in that forum if the below does not help.
Windows 10 - Chrome Zoom keeps changing - Microsoft Community
I have discovered it is the multi finger scroll thing for the touchpad. I had changed it on Windows 8 and had no problems so went and looked and changed it on Windows 10 - brilliant no more zooming in and out UNTIL I switched my laptop off. Even though I have changed the settings and applied them every time I turn my laptop off they reset themselves to multi finger scrolling!!! Why does it do this it is so annoying?
Plus the task bar (which I don't have locked in place) keeps locking and gets completely in the way. When you look at the settings it says it is unlocked so depending on what I am doing I have to keep moving it around th screen!!!!
any ideas would be appreciated.