I found this old thread which said that Google chrome does not allow you to override the default keyboard shortcuts which are provided by the browser
How can one disable shortcuts of chrome?
Has this situation changed now? I find the default Alt+Left behavior pretty annoying because it interferes with my default keyboard shortcuts. I like to use Alt+Left and Alt+right to move to the beginning and end of line rather than change page.
How can I override the default keyboard shortcuts?
Use the browser extension Shortkeys
Create a Keyboard Shortcut using "alt+left" and set the Behavior to "Do nothing"