Is there a way to tell Chrome web debugger to show the current mouse position in page coordinates?

You could type this into the console,

document.onmousemove = function(e){
var x = e.pageX;
var y = e.pageY;
e.target.title = "X is "+x+" and Y is "+y;
};

This will give you mouse position on mouse move in the element tooltip.

Combining ppsreejith's answer with JHarding's answer with Chrome 70+'s Live Expressions you can get constantly updating (x, y) coordinates without filling up the devtools console:

Enter this in the console:

var x, y; document.onmousemove=(e)=>{x=e.pageX;y=e.pageY;}

Enter this as a Live Expression:

"("+x+", "+y+")"

And this works on SVGs.

When i need to see the coordinates for my mouse, i use this Chrome addon: Coordinates addon