Override Chrome's Command+"+/-" for Multitouch Trackpad Pinch/Spread

Right now, if I am running Roll20 on my laptop and I use a "pinch" or "spread" gesture on the map, it changes all the font sizes for the chat window and all that jazz. Considering how awesome it is to use a multitouch trackpad for scrolling, wouldn't it be sweet to use if for zooming also? I'm not certain, but I seem to recall that you can override browser keyboard shortcuts in Javascript. (maybe stating the obvious here) You could change Command+"+/-" shortcut to map to Alt+Scrollwheel... or detect for pinch-swipe directly if they have that set up somewhere.

Come to think of it, it would be nice if there was more concurrency between the zoom tool and the Alt-scrollwheel method.

The expected behavior of Command+(+/-) in this application is definitely map zoom also, although I don't know if that's kosher from an accessibility standpoint.

And lastly, it would be very cool if there were a display showing the current level of zoom that popped up while you were zooming and then dismissed itself once the zooming had ended for a .5 seconds.

Come to think of it, it would be nice if there was more concurrency between the zoom tool and the Alt-scrollwheel method. I agree very much with this. I often use zoom in backgrounds and maps beyond the 150% maximum of the current Zoom tool by means of Alt+Mousewheel, making that lack of concurrency pretty evident.

Any word on this? I was just using google maps and finding myself a) wishing that it worked more like roll20 with its scrolling and b) realizing that it, too, does not zoom intuitively with pinch/spread gestures... I'm far from a web development guru, but I had thought that overriding keyboard commands was a relatively trivial thing?