Can you try a clean boot and check ?
My own computer have ever encountered similar problem with yours. Even reinstall system also encounter same problem. At last, it was verified to be keyboard problem.
For your problem, if it is desktop PC, it would be better to switch another keyboard for test.
On the other hand, you can check Event Viewer if it identify this problem.
You can also try to use system restore to revert your system to a former normal time point for test to fix this problem.
Is everything normal before?
is there any changes before this issue happen? (install, reinstall, update)
did you try system restore?
may I know your PC model. Is it comes with touchscreen?
did you try to installed different version of Chrome?
did that chrome playing some video/flash when your PC automatically scroll out?
did you try to run chrome without plugin? follow the step from DavidPostill
try to check at safe mode with networking, if issue don't persist, please do clean boot as arnavsharma suggest
I know that you also posted this issue to Google support, please do both way and let us know the update from browser support side
- Edited by britishdhez 6 minutes ago